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llvm-project/clang/lib/Sema/SemaTemplateDeduction.cpp

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//===- SemaTemplateDeduction.cpp - Template Argument Deduction ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements C++ template argument deduction.
//
//===----------------------------------------------------------------------===//
#include "TreeTransform.h"
#include "TypeLocBuilder.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclAccessPair.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclarationName.h"
#include "clang/AST/DynamicRecursiveASTVisitor.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/AST/TemplateBase.h"
#include "clang/AST/TemplateName.h"
#include "clang/AST/Type.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/TypeOrdering.h"
#include "clang/AST/UnresolvedSet.h"
#include "clang/Basic/AddressSpaces.h"
#include "clang/Basic/ExceptionSpecificationType.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Sema/EnterExpressionEvaluationContext.h"
#include "clang/Sema/Ownership.h"
#include "clang/Sema/Sema.h"
#include "clang/Sema/Template.h"
#include "clang/Sema/TemplateDeduction.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SaveAndRestore.h"
#include <algorithm>
#include <cassert>
#include <optional>
#include <tuple>
#include <type_traits>
#include <utility>
namespace clang {
/// Various flags that control template argument deduction.
///
/// These flags can be bitwise-OR'd together.
enum TemplateDeductionFlags {
/// No template argument deduction flags, which indicates the
/// strictest results for template argument deduction (as used for, e.g.,
/// matching class template partial specializations).
TDF_None = 0,
/// Within template argument deduction from a function call, we are
/// matching with a parameter type for which the original parameter was
/// a reference.
TDF_ParamWithReferenceType = 0x1,
/// Within template argument deduction from a function call, we
/// are matching in a case where we ignore cv-qualifiers.
TDF_IgnoreQualifiers = 0x02,
/// Within template argument deduction from a function call,
/// we are matching in a case where we can perform template argument
/// deduction from a template-id of a derived class of the argument type.
TDF_DerivedClass = 0x04,
/// Allow non-dependent types to differ, e.g., when performing
/// template argument deduction from a function call where conversions
/// may apply.
TDF_SkipNonDependent = 0x08,
/// Whether we are performing template argument deduction for
/// parameters and arguments in a top-level template argument
TDF_TopLevelParameterTypeList = 0x10,
/// Within template argument deduction from overload resolution per
/// C++ [over.over] allow matching function types that are compatible in
/// terms of noreturn and default calling convention adjustments, or
/// similarly matching a declared template specialization against a
/// possible template, per C++ [temp.deduct.decl]. In either case, permit
/// deduction where the parameter is a function type that can be converted
/// to the argument type.
TDF_AllowCompatibleFunctionType = 0x20,
/// Within template argument deduction for a conversion function, we are
/// matching with an argument type for which the original argument was
/// a reference.
TDF_ArgWithReferenceType = 0x40,
};
}
using namespace clang;
using namespace sema;
/// Compare two APSInts, extending and switching the sign as
/// necessary to compare their values regardless of underlying type.
static bool hasSameExtendedValue(llvm::APSInt X, llvm::APSInt Y) {
if (Y.getBitWidth() > X.getBitWidth())
X = X.extend(Y.getBitWidth());
else if (Y.getBitWidth() < X.getBitWidth())
Y = Y.extend(X.getBitWidth());
// If there is a signedness mismatch, correct it.
if (X.isSigned() != Y.isSigned()) {
// If the signed value is negative, then the values cannot be the same.
if ((Y.isSigned() && Y.isNegative()) || (X.isSigned() && X.isNegative()))
return false;
Y.setIsSigned(true);
X.setIsSigned(true);
}
return X == Y;
}
/// The kind of PartialOrdering we're performing template argument deduction
/// for (C++11 [temp.deduct.partial]).
enum class PartialOrderingKind { None, NonCall, Call };
static TemplateDeductionResult DeduceTemplateArgumentsByTypeMatch(
Sema &S, TemplateParameterList *TemplateParams, QualType Param,
QualType Arg, TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced, unsigned TDF,
PartialOrderingKind POK, bool DeducedFromArrayBound,
bool *HasDeducedAnyParam);
/// What directions packs are allowed to match non-packs.
enum class PackFold { ParameterToArgument, ArgumentToParameter, Both };
static TemplateDeductionResult
DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
ArrayRef<TemplateArgument> Ps,
ArrayRef<TemplateArgument> As,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool NumberOfArgumentsMustMatch, bool PartialOrdering,
PackFold PackFold, bool *HasDeducedAnyParam);
static void MarkUsedTemplateParameters(ASTContext &Ctx,
const TemplateArgument &TemplateArg,
bool OnlyDeduced, unsigned Depth,
llvm::SmallBitVector &Used);
static void MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
bool OnlyDeduced, unsigned Level,
llvm::SmallBitVector &Deduced);
/// If the given expression is of a form that permits the deduction
/// of a non-type template parameter, return the declaration of that
/// non-type template parameter.
static const NonTypeTemplateParmDecl *
getDeducedParameterFromExpr(const Expr *E, unsigned Depth) {
// If we are within an alias template, the expression may have undergone
// any number of parameter substitutions already.
while (true) {
if (const auto *IC = dyn_cast<ImplicitCastExpr>(E))
E = IC->getSubExpr();
else if (const auto *CE = dyn_cast<ConstantExpr>(E))
E = CE->getSubExpr();
else if (const auto *Subst = dyn_cast<SubstNonTypeTemplateParmExpr>(E))
E = Subst->getReplacement();
else if (const auto *CCE = dyn_cast<CXXConstructExpr>(E)) {
// Look through implicit copy construction from an lvalue of the same type.
if (CCE->getParenOrBraceRange().isValid())
break;
// Note, there could be default arguments.
assert(CCE->getNumArgs() >= 1 && "implicit construct expr should have 1 arg");
E = CCE->getArg(0);
} else
break;
}
if (const auto *DRE = dyn_cast<DeclRefExpr>(E))
if (const auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl()))
if (NTTP->getDepth() == Depth)
return NTTP;
return nullptr;
}
static const NonTypeTemplateParmDecl *
getDeducedParameterFromExpr(TemplateDeductionInfo &Info, Expr *E) {
return getDeducedParameterFromExpr(E, Info.getDeducedDepth());
}
/// Determine whether two declaration pointers refer to the same
/// declaration.
static bool isSameDeclaration(Decl *X, Decl *Y) {
if (NamedDecl *NX = dyn_cast<NamedDecl>(X))
X = NX->getUnderlyingDecl();
if (NamedDecl *NY = dyn_cast<NamedDecl>(Y))
Y = NY->getUnderlyingDecl();
return X->getCanonicalDecl() == Y->getCanonicalDecl();
}
/// Verify that the given, deduced template arguments are compatible.
///
/// \returns The deduced template argument, or a NULL template argument if
/// the deduced template arguments were incompatible.
static DeducedTemplateArgument
checkDeducedTemplateArguments(ASTContext &Context,
const DeducedTemplateArgument &X,
const DeducedTemplateArgument &Y,
bool AggregateCandidateDeduction = false) {
// We have no deduction for one or both of the arguments; they're compatible.
if (X.isNull())
return Y;
if (Y.isNull())
return X;
// If we have two non-type template argument values deduced for the same
// parameter, they must both match the type of the parameter, and thus must
// match each other's type. As we're only keeping one of them, we must check
// for that now. The exception is that if either was deduced from an array
// bound, the type is permitted to differ.
if (!X.wasDeducedFromArrayBound() && !Y.wasDeducedFromArrayBound()) {
QualType XType = X.getNonTypeTemplateArgumentType();
if (!XType.isNull()) {
QualType YType = Y.getNonTypeTemplateArgumentType();
if (YType.isNull() || !Context.hasSameType(XType, YType))
return DeducedTemplateArgument();
}
}
switch (X.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Non-deduced template arguments handled above");
case TemplateArgument::Type: {
// If two template type arguments have the same type, they're compatible.
QualType TX = X.getAsType(), TY = Y.getAsType();
if (Y.getKind() == TemplateArgument::Type && Context.hasSameType(TX, TY))
return DeducedTemplateArgument(Context.getCommonSugaredType(TX, TY),
X.wasDeducedFromArrayBound() ||
Y.wasDeducedFromArrayBound());
// If one of the two arguments was deduced from an array bound, the other
// supersedes it.
if (X.wasDeducedFromArrayBound() != Y.wasDeducedFromArrayBound())
return X.wasDeducedFromArrayBound() ? Y : X;
// The arguments are not compatible.
return DeducedTemplateArgument();
}
case TemplateArgument::Integral:
// If we deduced a constant in one case and either a dependent expression or
// declaration in another case, keep the integral constant.
// If both are integral constants with the same value, keep that value.
if (Y.getKind() == TemplateArgument::Expression ||
Y.getKind() == TemplateArgument::Declaration ||
(Y.getKind() == TemplateArgument::Integral &&
hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral())))
return X.wasDeducedFromArrayBound() ? Y : X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::StructuralValue:
// If we deduced a value and a dependent expression, keep the value.
if (Y.getKind() == TemplateArgument::Expression ||
(Y.getKind() == TemplateArgument::StructuralValue &&
X.structurallyEquals(Y)))
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::Template:
if (Y.getKind() == TemplateArgument::Template &&
Context.hasSameTemplateName(X.getAsTemplate(), Y.getAsTemplate()))
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::TemplateExpansion:
if (Y.getKind() == TemplateArgument::TemplateExpansion &&
Context.hasSameTemplateName(X.getAsTemplateOrTemplatePattern(),
Y.getAsTemplateOrTemplatePattern()))
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::Expression: {
if (Y.getKind() != TemplateArgument::Expression)
return checkDeducedTemplateArguments(Context, Y, X);
// Compare the expressions for equality
llvm::FoldingSetNodeID ID1, ID2;
X.getAsExpr()->Profile(ID1, Context, true);
Y.getAsExpr()->Profile(ID2, Context, true);
if (ID1 == ID2)
return X.wasDeducedFromArrayBound() ? Y : X;
// Differing dependent expressions are incompatible.
return DeducedTemplateArgument();
}
case TemplateArgument::Declaration:
assert(!X.wasDeducedFromArrayBound());
// If we deduced a declaration and a dependent expression, keep the
// declaration.
if (Y.getKind() == TemplateArgument::Expression)
return X;
// If we deduced a declaration and an integral constant, keep the
// integral constant and whichever type did not come from an array
// bound.
if (Y.getKind() == TemplateArgument::Integral) {
if (Y.wasDeducedFromArrayBound())
return TemplateArgument(Context, Y.getAsIntegral(),
X.getParamTypeForDecl());
return Y;
}
// If we deduced two declarations, make sure that they refer to the
// same declaration.
if (Y.getKind() == TemplateArgument::Declaration &&
isSameDeclaration(X.getAsDecl(), Y.getAsDecl()))
return X;
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::NullPtr:
// If we deduced a null pointer and a dependent expression, keep the
// null pointer.
if (Y.getKind() == TemplateArgument::Expression)
return TemplateArgument(Context.getCommonSugaredType(
X.getNullPtrType(), Y.getAsExpr()->getType()),
true);
// If we deduced a null pointer and an integral constant, keep the
// integral constant.
if (Y.getKind() == TemplateArgument::Integral)
return Y;
// If we deduced two null pointers, they are the same.
if (Y.getKind() == TemplateArgument::NullPtr)
return TemplateArgument(
Context.getCommonSugaredType(X.getNullPtrType(), Y.getNullPtrType()),
true);
// All other combinations are incompatible.
return DeducedTemplateArgument();
case TemplateArgument::Pack: {
if (Y.getKind() != TemplateArgument::Pack ||
(!AggregateCandidateDeduction && X.pack_size() != Y.pack_size()))
return DeducedTemplateArgument();
llvm::SmallVector<TemplateArgument, 8> NewPack;
for (TemplateArgument::pack_iterator
XA = X.pack_begin(),
XAEnd = X.pack_end(), YA = Y.pack_begin(), YAEnd = Y.pack_end();
XA != XAEnd; ++XA) {
if (YA != YAEnd) {
TemplateArgument Merged = checkDeducedTemplateArguments(
Context, DeducedTemplateArgument(*XA, X.wasDeducedFromArrayBound()),
DeducedTemplateArgument(*YA, Y.wasDeducedFromArrayBound()));
if (Merged.isNull() && !(XA->isNull() && YA->isNull()))
return DeducedTemplateArgument();
NewPack.push_back(Merged);
++YA;
} else {
NewPack.push_back(*XA);
}
}
return DeducedTemplateArgument(
TemplateArgument::CreatePackCopy(Context, NewPack),
X.wasDeducedFromArrayBound() && Y.wasDeducedFromArrayBound());
}
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
/// Deduce the value of the given non-type template parameter
/// as the given deduced template argument. All non-type template parameter
/// deduction is funneled through here.
static TemplateDeductionResult
DeduceNonTypeTemplateArgument(Sema &S, TemplateParameterList *TemplateParams,
const NonTypeTemplateParmDecl *NTTP,
const DeducedTemplateArgument &NewDeduced,
QualType ValueType, TemplateDeductionInfo &Info,
bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
assert(NTTP->getDepth() == Info.getDeducedDepth() &&
"deducing non-type template argument with wrong depth");
DeducedTemplateArgument Result = checkDeducedTemplateArguments(
S.Context, Deduced[NTTP->getIndex()], NewDeduced);
if (Result.isNull()) {
Info.Param = const_cast<NonTypeTemplateParmDecl*>(NTTP);
Info.FirstArg = Deduced[NTTP->getIndex()];
Info.SecondArg = NewDeduced;
return TemplateDeductionResult::Inconsistent;
}
Deduced[NTTP->getIndex()] = Result;
if (!S.getLangOpts().CPlusPlus17)
return TemplateDeductionResult::Success;
if (NTTP->isExpandedParameterPack())
// FIXME: We may still need to deduce parts of the type here! But we
// don't have any way to find which slice of the type to use, and the
// type stored on the NTTP itself is nonsense. Perhaps the type of an
// expanded NTTP should be a pack expansion type?
return TemplateDeductionResult::Success;
// Get the type of the parameter for deduction. If it's a (dependent) array
// or function type, we will not have decayed it yet, so do that now.
QualType ParamType = S.Context.getAdjustedParameterType(NTTP->getType());
if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
ParamType = Expansion->getPattern();
// FIXME: It's not clear how deduction of a parameter of reference
// type from an argument (of non-reference type) should be performed.
// For now, we just make the argument have same reference type as the
// parameter.
if (ParamType->isReferenceType() && !ValueType->isReferenceType()) {
if (ParamType->isRValueReferenceType())
ValueType = S.Context.getRValueReferenceType(ValueType);
else
ValueType = S.Context.getLValueReferenceType(ValueType);
}
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, ParamType, ValueType, Info, Deduced,
TDF_SkipNonDependent | TDF_IgnoreQualifiers,
PartialOrdering ? PartialOrderingKind::NonCall
: PartialOrderingKind::None,
/*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound(), HasDeducedAnyParam);
}
/// Deduce the value of the given non-type template parameter
/// from the given integral constant.
static TemplateDeductionResult DeduceNonTypeTemplateArgument(
Sema &S, TemplateParameterList *TemplateParams,
const NonTypeTemplateParmDecl *NTTP, const llvm::APSInt &Value,
QualType ValueType, bool DeducedFromArrayBound, TemplateDeductionInfo &Info,
bool PartialOrdering, SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP,
DeducedTemplateArgument(S.Context, Value, ValueType,
DeducedFromArrayBound),
ValueType, Info, PartialOrdering, Deduced, HasDeducedAnyParam);
}
/// Deduce the value of the given non-type template parameter
/// from the given null pointer template argument type.
static TemplateDeductionResult
DeduceNullPtrTemplateArgument(Sema &S, TemplateParameterList *TemplateParams,
const NonTypeTemplateParmDecl *NTTP,
QualType NullPtrType, TemplateDeductionInfo &Info,
bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
Expr *Value = S.ImpCastExprToType(
new (S.Context) CXXNullPtrLiteralExpr(S.Context.NullPtrTy,
NTTP->getLocation()),
NullPtrType,
NullPtrType->isMemberPointerType() ? CK_NullToMemberPointer
: CK_NullToPointer)
.get();
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, DeducedTemplateArgument(Value), Value->getType(),
Info, PartialOrdering, Deduced, HasDeducedAnyParam);
}
/// Deduce the value of the given non-type template parameter
/// from the given type- or value-dependent expression.
///
/// \returns true if deduction succeeded, false otherwise.
static TemplateDeductionResult
DeduceNonTypeTemplateArgument(Sema &S, TemplateParameterList *TemplateParams,
const NonTypeTemplateParmDecl *NTTP, Expr *Value,
TemplateDeductionInfo &Info, bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, DeducedTemplateArgument(Value), Value->getType(),
Info, PartialOrdering, Deduced, HasDeducedAnyParam);
}
/// Deduce the value of the given non-type template parameter
/// from the given declaration.
///
/// \returns true if deduction succeeded, false otherwise.
static TemplateDeductionResult
DeduceNonTypeTemplateArgument(Sema &S, TemplateParameterList *TemplateParams,
const NonTypeTemplateParmDecl *NTTP, ValueDecl *D,
QualType T, TemplateDeductionInfo &Info,
bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
TemplateArgument New(D, T);
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, DeducedTemplateArgument(New), T, Info,
PartialOrdering, Deduced, HasDeducedAnyParam);
}
static TemplateDeductionResult DeduceTemplateArguments(
Sema &S, TemplateParameterList *TemplateParams, TemplateName Param,
TemplateName Arg, TemplateDeductionInfo &Info,
ArrayRef<TemplateArgument> DefaultArguments, bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
TemplateDecl *ParamDecl = Param.getAsTemplateDecl();
if (!ParamDecl) {
// The parameter type is dependent and is not a template template parameter,
// so there is nothing that we can deduce.
return TemplateDeductionResult::Success;
}
if (auto *TempParam = dyn_cast<TemplateTemplateParmDecl>(ParamDecl)) {
// If we're not deducing at this depth, there's nothing to deduce.
if (TempParam->getDepth() != Info.getDeducedDepth())
return TemplateDeductionResult::Success;
ArrayRef<NamedDecl *> Params =
ParamDecl->getTemplateParameters()->asArray();
unsigned StartPos = 0;
for (unsigned I = 0, E = std::min(Params.size(), DefaultArguments.size());
I < E; ++I) {
if (Params[I]->isParameterPack()) {
StartPos = DefaultArguments.size();
break;
}
StartPos = I + 1;
}
// Provisional resolution for CWG2398: If Arg names a template
// specialization, then we deduce a synthesized template name
// based on A, but using the TS's extra arguments, relative to P, as
// defaults.
DeducedTemplateArgument NewDeduced =
PartialOrdering
? TemplateArgument(S.Context.getDeducedTemplateName(
Arg, {StartPos, DefaultArguments.drop_front(StartPos)}))
: Arg;
DeducedTemplateArgument Result = checkDeducedTemplateArguments(
S.Context, Deduced[TempParam->getIndex()], NewDeduced);
if (Result.isNull()) {
Info.Param = TempParam;
Info.FirstArg = Deduced[TempParam->getIndex()];
Info.SecondArg = NewDeduced;
return TemplateDeductionResult::Inconsistent;
}
Deduced[TempParam->getIndex()] = Result;
if (HasDeducedAnyParam)
*HasDeducedAnyParam = true;
return TemplateDeductionResult::Success;
}
// Verify that the two template names are equivalent.
if (S.Context.hasSameTemplateName(
Param, Arg, /*IgnoreDeduced=*/DefaultArguments.size() != 0))
return TemplateDeductionResult::Success;
// Mismatch of non-dependent template parameter to argument.
Info.FirstArg = TemplateArgument(Param);
Info.SecondArg = TemplateArgument(Arg);
return TemplateDeductionResult::NonDeducedMismatch;
}
/// Deduce the template arguments by comparing the template parameter
/// type (which is a template-id) with the template argument type.
///
/// \param S the Sema
///
/// \param TemplateParams the template parameters that we are deducing
///
/// \param P the parameter type
///
/// \param A the argument type
///
/// \param Info information about the template argument deduction itself
///
/// \param Deduced the deduced template arguments
///
/// \returns the result of template argument deduction so far. Note that a
/// "success" result means that template argument deduction has not yet failed,
/// but it may still fail, later, for other reasons.
static const TemplateSpecializationType *getLastTemplateSpecType(QualType QT) {
for (const Type *T = QT.getTypePtr(); /**/; /**/) {
const TemplateSpecializationType *TST =
T->getAs<TemplateSpecializationType>();
assert(TST && "Expected a TemplateSpecializationType");
if (!TST->isSugared())
return TST;
T = TST->desugar().getTypePtr();
}
}
static TemplateDeductionResult
DeduceTemplateSpecArguments(Sema &S, TemplateParameterList *TemplateParams,
const QualType P, QualType A,
TemplateDeductionInfo &Info, bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
QualType UP = P;
if (const auto *IP = P->getAs<InjectedClassNameType>())
UP = IP->getInjectedSpecializationType();
assert(isa<TemplateSpecializationType>(UP.getCanonicalType()));
const TemplateSpecializationType *TP = ::getLastTemplateSpecType(UP);
TemplateName TNP = TP->getTemplateName();
// If the parameter is an alias template, there is nothing to deduce.
if (const auto *TD = TNP.getAsTemplateDecl(); TD && TD->isTypeAlias())
return TemplateDeductionResult::Success;
// FIXME: To preserve sugar, the TST needs to carry sugared resolved
// arguments.
ArrayRef<TemplateArgument> PResolved =
TP->getCanonicalTypeInternal()
->castAs<TemplateSpecializationType>()
->template_arguments();
QualType UA = A;
std::optional<NestedNameSpecifier *> NNS;
// Treat an injected-class-name as its underlying template-id.
if (const auto *Elaborated = A->getAs<ElaboratedType>()) {
NNS = Elaborated->getQualifier();
} else if (const auto *Injected = A->getAs<InjectedClassNameType>()) {
UA = Injected->getInjectedSpecializationType();
NNS = nullptr;
}
// Check whether the template argument is a dependent template-id.
if (isa<TemplateSpecializationType>(UA.getCanonicalType())) {
const TemplateSpecializationType *SA = ::getLastTemplateSpecType(UA);
TemplateName TNA = SA->getTemplateName();
// If the argument is an alias template, there is nothing to deduce.
if (const auto *TD = TNA.getAsTemplateDecl(); TD && TD->isTypeAlias())
return TemplateDeductionResult::Success;
// FIXME: To preserve sugar, the TST needs to carry sugared resolved
// arguments.
ArrayRef<TemplateArgument> AResolved =
SA->getCanonicalTypeInternal()
->castAs<TemplateSpecializationType>()
->template_arguments();
// Perform template argument deduction for the template name.
if (auto Result = DeduceTemplateArguments(S, TemplateParams, TNP, TNA, Info,
/*DefaultArguments=*/AResolved,
PartialOrdering, Deduced,
HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform template argument deduction on each template
// argument. Ignore any missing/extra arguments, since they could be
// filled in by default arguments.
return DeduceTemplateArguments(
S, TemplateParams, PResolved, AResolved, Info, Deduced,
/*NumberOfArgumentsMustMatch=*/false, PartialOrdering,
PackFold::ParameterToArgument, HasDeducedAnyParam);
}
// If the argument type is a class template specialization, we
// perform template argument deduction using its template
// arguments.
const auto *RA = UA->getAs<RecordType>();
const auto *SA =
RA ? dyn_cast<ClassTemplateSpecializationDecl>(RA->getDecl()) : nullptr;
if (!SA) {
Info.FirstArg = TemplateArgument(P);
Info.SecondArg = TemplateArgument(A);
return TemplateDeductionResult::NonDeducedMismatch;
}
TemplateName TNA = TemplateName(SA->getSpecializedTemplate());
if (NNS)
TNA = S.Context.getQualifiedTemplateName(
*NNS, false, TemplateName(SA->getSpecializedTemplate()));
// Perform template argument deduction for the template name.
if (auto Result = DeduceTemplateArguments(
S, TemplateParams, TNP, TNA, Info,
/*DefaultArguments=*/SA->getTemplateArgs().asArray(), PartialOrdering,
Deduced, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform template argument deduction for the template arguments.
return DeduceTemplateArguments(S, TemplateParams, PResolved,
SA->getTemplateArgs().asArray(), Info, Deduced,
/*NumberOfArgumentsMustMatch=*/true,
PartialOrdering, PackFold::ParameterToArgument,
HasDeducedAnyParam);
}
static bool IsPossiblyOpaquelyQualifiedTypeInternal(const Type *T) {
assert(T->isCanonicalUnqualified());
switch (T->getTypeClass()) {
case Type::TypeOfExpr:
case Type::TypeOf:
case Type::DependentName:
case Type::Decltype:
case Type::PackIndexing:
case Type::UnresolvedUsing:
case Type::TemplateTypeParm:
case Type::Auto:
return true;
case Type::ConstantArray:
case Type::IncompleteArray:
case Type::VariableArray:
case Type::DependentSizedArray:
return IsPossiblyOpaquelyQualifiedTypeInternal(
cast<ArrayType>(T)->getElementType().getTypePtr());
default:
return false;
}
}
/// Determines whether the given type is an opaque type that
/// might be more qualified when instantiated.
static bool IsPossiblyOpaquelyQualifiedType(QualType T) {
return IsPossiblyOpaquelyQualifiedTypeInternal(
T->getCanonicalTypeInternal().getTypePtr());
}
/// Helper function to build a TemplateParameter when we don't
/// know its type statically.
static TemplateParameter makeTemplateParameter(Decl *D) {
if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(D))
return TemplateParameter(TTP);
if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D))
return TemplateParameter(NTTP);
return TemplateParameter(cast<TemplateTemplateParmDecl>(D));
}
/// A pack that we're currently deducing.
struct clang::DeducedPack {
// The index of the pack.
unsigned Index;
// The old value of the pack before we started deducing it.
DeducedTemplateArgument Saved;
// A deferred value of this pack from an inner deduction, that couldn't be
// deduced because this deduction hadn't happened yet.
DeducedTemplateArgument DeferredDeduction;
// The new value of the pack.
SmallVector<DeducedTemplateArgument, 4> New;
// The outer deduction for this pack, if any.
DeducedPack *Outer = nullptr;
DeducedPack(unsigned Index) : Index(Index) {}
};
namespace {
/// A scope in which we're performing pack deduction.
class PackDeductionScope {
public:
/// Prepare to deduce the packs named within Pattern.
/// \param FinishingDeduction Don't attempt to deduce the pack. Useful when
/// just checking a previous deduction of the pack.
PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info, TemplateArgument Pattern,
bool DeducePackIfNotAlreadyDeduced = false,
bool FinishingDeduction = false)
: S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info),
DeducePackIfNotAlreadyDeduced(DeducePackIfNotAlreadyDeduced),
FinishingDeduction(FinishingDeduction) {
unsigned NumNamedPacks = addPacks(Pattern);
finishConstruction(NumNamedPacks);
}
/// Prepare to directly deduce arguments of the parameter with index \p Index.
PackDeductionScope(Sema &S, TemplateParameterList *TemplateParams,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info, unsigned Index)
: S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
addPack(Index);
finishConstruction(1);
}
private:
void addPack(unsigned Index) {
// Save the deduced template argument for the parameter pack expanded
// by this pack expansion, then clear out the deduction.
DeducedFromEarlierParameter = !Deduced[Index].isNull();
DeducedPack Pack(Index);
if (!FinishingDeduction) {
Pack.Saved = Deduced[Index];
Deduced[Index] = TemplateArgument();
}
// FIXME: What if we encounter multiple packs with different numbers of
// pre-expanded expansions? (This should already have been diagnosed
// during substitution.)
if (std::optional<unsigned> ExpandedPackExpansions =
getExpandedPackSize(TemplateParams->getParam(Index)))
FixedNumExpansions = ExpandedPackExpansions;
Packs.push_back(Pack);
}
unsigned addPacks(TemplateArgument Pattern) {
// Compute the set of template parameter indices that correspond to
// parameter packs expanded by the pack expansion.
llvm::SmallBitVector SawIndices(TemplateParams->size());
llvm::SmallVector<TemplateArgument, 4> ExtraDeductions;
auto AddPack = [&](unsigned Index) {
if (SawIndices[Index])
return;
SawIndices[Index] = true;
addPack(Index);
// Deducing a parameter pack that is a pack expansion also constrains the
// packs appearing in that parameter to have the same deduced arity. Also,
// in C++17 onwards, deducing a non-type template parameter deduces its
// type, so we need to collect the pending deduced values for those packs.
if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(
TemplateParams->getParam(Index))) {
if (!NTTP->isExpandedParameterPack())
// FIXME: CWG2982 suggests a type-constraint forms a non-deduced
// context, however it is not yet resolved.
if (auto *Expansion = dyn_cast<PackExpansionType>(
S.Context.getUnconstrainedType(NTTP->getType())))
ExtraDeductions.push_back(Expansion->getPattern());
}
// FIXME: Also collect the unexpanded packs in any type and template
// parameter packs that are pack expansions.
};
auto Collect = [&](TemplateArgument Pattern) {
SmallVector<UnexpandedParameterPack, 2> Unexpanded;
S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
unsigned Depth, Index;
std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
if (Depth == Info.getDeducedDepth())
AddPack(Index);
}
};
// Look for unexpanded packs in the pattern.
Collect(Pattern);
assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
unsigned NumNamedPacks = Packs.size();
// Also look for unexpanded packs that are indirectly deduced by deducing
// the sizes of the packs in this pattern.
while (!ExtraDeductions.empty())
Collect(ExtraDeductions.pop_back_val());
return NumNamedPacks;
}
void finishConstruction(unsigned NumNamedPacks) {
// Dig out the partially-substituted pack, if there is one.
const TemplateArgument *PartialPackArgs = nullptr;
unsigned NumPartialPackArgs = 0;
std::pair<unsigned, unsigned> PartialPackDepthIndex(-1u, -1u);
if (auto *Scope = S.CurrentInstantiationScope)
if (auto *Partial = Scope->getPartiallySubstitutedPack(
&PartialPackArgs, &NumPartialPackArgs))
PartialPackDepthIndex = getDepthAndIndex(Partial);
// This pack expansion will have been partially or fully expanded if
// it only names explicitly-specified parameter packs (including the
// partially-substituted one, if any).
bool IsExpanded = true;
for (unsigned I = 0; I != NumNamedPacks; ++I) {
if (Packs[I].Index >= Info.getNumExplicitArgs()) {
IsExpanded = false;
IsPartiallyExpanded = false;
break;
}
if (PartialPackDepthIndex ==
std::make_pair(Info.getDeducedDepth(), Packs[I].Index)) {
IsPartiallyExpanded = true;
}
}
// Skip over the pack elements that were expanded into separate arguments.
// If we partially expanded, this is the number of partial arguments.
// FIXME: `&& FixedNumExpansions` is a workaround for UB described in
// https://github.com/llvm/llvm-project/issues/100095
if (IsPartiallyExpanded)
PackElements += NumPartialPackArgs;
else if (IsExpanded && FixedNumExpansions)
PackElements += *FixedNumExpansions;
for (auto &Pack : Packs) {
if (Info.PendingDeducedPacks.size() > Pack.Index)
Pack.Outer = Info.PendingDeducedPacks[Pack.Index];
else
Info.PendingDeducedPacks.resize(Pack.Index + 1);
Info.PendingDeducedPacks[Pack.Index] = &Pack;
if (PartialPackDepthIndex ==
std::make_pair(Info.getDeducedDepth(), Pack.Index)) {
Pack.New.append(PartialPackArgs, PartialPackArgs + NumPartialPackArgs);
// We pre-populate the deduced value of the partially-substituted
// pack with the specified value. This is not entirely correct: the
// value is supposed to have been substituted, not deduced, but the
// cases where this is observable require an exact type match anyway.
//
// FIXME: If we could represent a "depth i, index j, pack elem k"
// parameter, we could substitute the partially-substituted pack
// everywhere and avoid this.
if (!FinishingDeduction && !IsPartiallyExpanded)
Deduced[Pack.Index] = Pack.New[PackElements];
}
}
}
public:
~PackDeductionScope() {
for (auto &Pack : Packs)
Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
}
// Return the size of the saved packs if all of them has the same size.
std::optional<unsigned> getSavedPackSizeIfAllEqual() const {
unsigned PackSize = Packs[0].Saved.pack_size();
if (std::all_of(Packs.begin() + 1, Packs.end(), [&PackSize](const auto &P) {
return P.Saved.pack_size() == PackSize;
}))
return PackSize;
return {};
}
/// Determine whether this pack has already been deduced from a previous
/// argument.
bool isDeducedFromEarlierParameter() const {
return DeducedFromEarlierParameter;
}
/// Determine whether this pack has already been partially expanded into a
/// sequence of (prior) function parameters / template arguments.
bool isPartiallyExpanded() { return IsPartiallyExpanded; }
/// Determine whether this pack expansion scope has a known, fixed arity.
/// This happens if it involves a pack from an outer template that has
/// (notionally) already been expanded.
bool hasFixedArity() { return FixedNumExpansions.has_value(); }
/// Determine whether the next element of the argument is still part of this
/// pack. This is the case unless the pack is already expanded to a fixed
/// length.
bool hasNextElement() {
return !FixedNumExpansions || *FixedNumExpansions > PackElements;
}
/// Move to deducing the next element in each pack that is being deduced.
void nextPackElement() {
// Capture the deduced template arguments for each parameter pack expanded
// by this pack expansion, add them to the list of arguments we've deduced
// for that pack, then clear out the deduced argument.
if (!FinishingDeduction) {
for (auto &Pack : Packs) {
DeducedTemplateArgument &DeducedArg = Deduced[Pack.Index];
if (!Pack.New.empty() || !DeducedArg.isNull()) {
while (Pack.New.size() < PackElements)
Pack.New.push_back(DeducedTemplateArgument());
if (Pack.New.size() == PackElements)
Pack.New.push_back(DeducedArg);
else
Pack.New[PackElements] = DeducedArg;
DeducedArg = Pack.New.size() > PackElements + 1
? Pack.New[PackElements + 1]
: DeducedTemplateArgument();
}
}
}
++PackElements;
}
/// Finish template argument deduction for a set of argument packs,
/// producing the argument packs and checking for consistency with prior
/// deductions.
TemplateDeductionResult finish() {
if (FinishingDeduction)
return TemplateDeductionResult::Success;
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
for (auto &Pack : Packs) {
// Put back the old value for this pack.
if (!FinishingDeduction)
Deduced[Pack.Index] = Pack.Saved;
// Always make sure the size of this pack is correct, even if we didn't
// deduce any values for it.
//
// FIXME: This isn't required by the normative wording, but substitution
// and post-substitution checking will always fail if the arity of any
// pack is not equal to the number of elements we processed. (Either that
// or something else has gone *very* wrong.) We're permitted to skip any
// hard errors from those follow-on steps by the intent (but not the
// wording) of C++ [temp.inst]p8:
//
// If the function selected by overload resolution can be determined
// without instantiating a class template definition, it is unspecified
// whether that instantiation actually takes place
Pack.New.resize(PackElements);
// Build or find a new value for this pack.
DeducedTemplateArgument NewPack;
if (Pack.New.empty()) {
// If we deduced an empty argument pack, create it now.
NewPack = DeducedTemplateArgument(TemplateArgument::getEmptyPack());
} else {
TemplateArgument *ArgumentPack =
new (S.Context) TemplateArgument[Pack.New.size()];
std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
NewPack = DeducedTemplateArgument(
TemplateArgument(llvm::ArrayRef(ArgumentPack, Pack.New.size())),
// FIXME: This is wrong, it's possible that some pack elements are
// deduced from an array bound and others are not:
// template<typename ...T, T ...V> void g(const T (&...p)[V]);
// g({1, 2, 3}, {{}, {}});
// ... should deduce T = {int, size_t (from array bound)}.
Pack.New[0].wasDeducedFromArrayBound());
}
// Pick where we're going to put the merged pack.
DeducedTemplateArgument *Loc;
if (Pack.Outer) {
if (Pack.Outer->DeferredDeduction.isNull()) {
// Defer checking this pack until we have a complete pack to compare
// it against.
Pack.Outer->DeferredDeduction = NewPack;
continue;
}
Loc = &Pack.Outer->DeferredDeduction;
} else {
Loc = &Deduced[Pack.Index];
}
// Check the new pack matches any previous value.
DeducedTemplateArgument OldPack = *Loc;
DeducedTemplateArgument Result = checkDeducedTemplateArguments(
S.Context, OldPack, NewPack, DeducePackIfNotAlreadyDeduced);
Info.AggregateDeductionCandidateHasMismatchedArity =
OldPack.getKind() == TemplateArgument::Pack &&
NewPack.getKind() == TemplateArgument::Pack &&
OldPack.pack_size() != NewPack.pack_size() && !Result.isNull();
// If we deferred a deduction of this pack, check that one now too.
if (!Result.isNull() && !Pack.DeferredDeduction.isNull()) {
OldPack = Result;
NewPack = Pack.DeferredDeduction;
Result = checkDeducedTemplateArguments(S.Context, OldPack, NewPack);
}
NamedDecl *Param = TemplateParams->getParam(Pack.Index);
if (Result.isNull()) {
Info.Param = makeTemplateParameter(Param);
Info.FirstArg = OldPack;
Info.SecondArg = NewPack;
return TemplateDeductionResult::Inconsistent;
}
// If we have a pre-expanded pack and we didn't deduce enough elements
// for it, fail deduction.
if (std::optional<unsigned> Expansions = getExpandedPackSize(Param)) {
if (*Expansions != PackElements) {
Info.Param = makeTemplateParameter(Param);
Info.FirstArg = Result;
return TemplateDeductionResult::IncompletePack;
}
}
*Loc = Result;
}
return TemplateDeductionResult::Success;
}
private:
Sema &S;
TemplateParameterList *TemplateParams;
SmallVectorImpl<DeducedTemplateArgument> &Deduced;
TemplateDeductionInfo &Info;
unsigned PackElements = 0;
bool IsPartiallyExpanded = false;
bool DeducePackIfNotAlreadyDeduced = false;
bool DeducedFromEarlierParameter = false;
bool FinishingDeduction = false;
/// The number of expansions, if we have a fully-expanded pack in this scope.
std::optional<unsigned> FixedNumExpansions;
SmallVector<DeducedPack, 2> Packs;
};
} // namespace
template <class T>
static TemplateDeductionResult DeduceForEachType(
Sema &S, TemplateParameterList *TemplateParams, ArrayRef<QualType> Params,
ArrayRef<QualType> Args, TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced, PartialOrderingKind POK,
bool FinishingDeduction, T &&DeductFunc) {
// C++0x [temp.deduct.type]p10:
// Similarly, if P has a form that contains (T), then each parameter type
// Pi of the respective parameter-type- list of P is compared with the
// corresponding parameter type Ai of the corresponding parameter-type-list
// of A. [...]
unsigned ArgIdx = 0, ParamIdx = 0;
for (; ParamIdx != Params.size(); ++ParamIdx) {
// Check argument types.
const PackExpansionType *Expansion
= dyn_cast<PackExpansionType>(Params[ParamIdx]);
if (!Expansion) {
// Simple case: compare the parameter and argument types at this point.
// Make sure we have an argument.
if (ArgIdx >= Args.size())
return TemplateDeductionResult::MiscellaneousDeductionFailure;
if (isa<PackExpansionType>(Args[ArgIdx])) {
// C++0x [temp.deduct.type]p22:
// If the original function parameter associated with A is a function
// parameter pack and the function parameter associated with P is not
// a function parameter pack, then template argument deduction fails.
return TemplateDeductionResult::MiscellaneousDeductionFailure;
}
if (TemplateDeductionResult Result =
DeductFunc(S, TemplateParams, ParamIdx, ArgIdx,
Params[ParamIdx].getUnqualifiedType(),
Args[ArgIdx].getUnqualifiedType(), Info, Deduced, POK);
Result != TemplateDeductionResult::Success)
return Result;
++ArgIdx;
continue;
}
// C++0x [temp.deduct.type]p10:
// If the parameter-declaration corresponding to Pi is a function
// parameter pack, then the type of its declarator- id is compared with
// each remaining parameter type in the parameter-type-list of A. Each
// comparison deduces template arguments for subsequent positions in the
// template parameter packs expanded by the function parameter pack.
QualType Pattern = Expansion->getPattern();
PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern,
/*DeducePackIfNotAlreadyDeduced=*/false,
FinishingDeduction);
// A pack scope with fixed arity is not really a pack any more, so is not
// a non-deduced context.
if (ParamIdx + 1 == Params.size() || PackScope.hasFixedArity()) {
for (; ArgIdx < Args.size() && PackScope.hasNextElement(); ++ArgIdx) {
// Deduce template arguments from the pattern.
if (TemplateDeductionResult Result = DeductFunc(
S, TemplateParams, ParamIdx, ArgIdx,
Pattern.getUnqualifiedType(), Args[ArgIdx].getUnqualifiedType(),
Info, Deduced, POK);
Result != TemplateDeductionResult::Success)
return Result;
PackScope.nextPackElement();
}
} else {
// C++0x [temp.deduct.type]p5:
// The non-deduced contexts are:
// - A function parameter pack that does not occur at the end of the
// parameter-declaration-clause.
//
// FIXME: There is no wording to say what we should do in this case. We
// choose to resolve this by applying the same rule that is applied for a
// function call: that is, deduce all contained packs to their
// explicitly-specified values (or to <> if there is no such value).
//
// This is seemingly-arbitrarily different from the case of a template-id
// with a non-trailing pack-expansion in its arguments, which renders the
// entire template-argument-list a non-deduced context.
// If the parameter type contains an explicitly-specified pack that we
// could not expand, skip the number of parameters notionally created
// by the expansion.
std::optional<unsigned> NumExpansions = Expansion->getNumExpansions();
if (NumExpansions && !PackScope.isPartiallyExpanded()) {
for (unsigned I = 0; I != *NumExpansions && ArgIdx < Args.size();
++I, ++ArgIdx)
PackScope.nextPackElement();
}
}
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
if (auto Result = PackScope.finish();
Result != TemplateDeductionResult::Success)
return Result;
}
// DR692, DR1395
// C++0x [temp.deduct.type]p10:
// If the parameter-declaration corresponding to P_i ...
// During partial ordering, if Ai was originally a function parameter pack:
// - if P does not contain a function parameter type corresponding to Ai then
// Ai is ignored;
if (POK == PartialOrderingKind::Call && ArgIdx + 1 == Args.size() &&
isa<PackExpansionType>(Args[ArgIdx]))
return TemplateDeductionResult::Success;
// Make sure we don't have any extra arguments.
if (ArgIdx < Args.size())
return TemplateDeductionResult::MiscellaneousDeductionFailure;
return TemplateDeductionResult::Success;
}
/// Deduce the template arguments by comparing the list of parameter
/// types to the list of argument types, as in the parameter-type-lists of
/// function types (C++ [temp.deduct.type]p10).
///
/// \param S The semantic analysis object within which we are deducing
///
/// \param TemplateParams The template parameters that we are deducing
///
/// \param Params The list of parameter types
///
/// \param Args The list of argument types
///
/// \param Info information about the template argument deduction itself
///
/// \param Deduced the deduced template arguments
///
/// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
/// how template argument deduction is performed.
///
/// \param PartialOrdering If true, we are performing template argument
/// deduction for during partial ordering for a call
/// (C++0x [temp.deduct.partial]).
///
/// \param HasDeducedAnyParam If set, the object pointed at will indicate
/// whether any template parameter was deduced.
///
/// \param HasDeducedParam If set, the bit vector will be used to represent
/// which template parameters were deduced, in order.
///
/// \returns the result of template argument deduction so far. Note that a
/// "success" result means that template argument deduction has not yet failed,
/// but it may still fail, later, for other reasons.
static TemplateDeductionResult DeduceTemplateArguments(
Sema &S, TemplateParameterList *TemplateParams, ArrayRef<QualType> Params,
ArrayRef<QualType> Args, TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced, unsigned TDF,
PartialOrderingKind POK, bool *HasDeducedAnyParam,
llvm::SmallBitVector *HasDeducedParam) {
return ::DeduceForEachType(
S, TemplateParams, Params, Args, Info, Deduced, POK,
/*FinishingDeduction=*/false,
[&](Sema &S, TemplateParameterList *TemplateParams, int ParamIdx,
int ArgIdx, QualType P, QualType A, TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
PartialOrderingKind POK) {
bool HasDeducedAnyParamCopy = false;
TemplateDeductionResult TDR = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, P, A, Info, Deduced, TDF, POK,
/*DeducedFromArrayBound=*/false, &HasDeducedAnyParamCopy);
if (HasDeducedAnyParam && HasDeducedAnyParamCopy)
*HasDeducedAnyParam = true;
if (HasDeducedParam && HasDeducedAnyParamCopy)
(*HasDeducedParam)[ParamIdx] = true;
return TDR;
});
}
/// Determine whether the parameter has qualifiers that the argument
/// lacks. Put another way, determine whether there is no way to add
/// a deduced set of qualifiers to the ParamType that would result in
/// its qualifiers matching those of the ArgType.
static bool hasInconsistentOrSupersetQualifiersOf(QualType ParamType,
QualType ArgType) {
Qualifiers ParamQs = ParamType.getQualifiers();
Qualifiers ArgQs = ArgType.getQualifiers();
if (ParamQs == ArgQs)
return false;
// Mismatched (but not missing) Objective-C GC attributes.
if (ParamQs.getObjCGCAttr() != ArgQs.getObjCGCAttr() &&
ParamQs.hasObjCGCAttr())
return true;
// Mismatched (but not missing) address spaces.
if (ParamQs.getAddressSpace() != ArgQs.getAddressSpace() &&
ParamQs.hasAddressSpace())
return true;
// Mismatched (but not missing) Objective-C lifetime qualifiers.
if (ParamQs.getObjCLifetime() != ArgQs.getObjCLifetime() &&
ParamQs.hasObjCLifetime())
return true;
// CVR qualifiers inconsistent or a superset.
return (ParamQs.getCVRQualifiers() & ~ArgQs.getCVRQualifiers()) != 0;
}
bool Sema::isSameOrCompatibleFunctionType(QualType P, QualType A) {
const FunctionType *PF = P->getAs<FunctionType>(),
*AF = A->getAs<FunctionType>();
// Just compare if not functions.
if (!PF || !AF)
return Context.hasSameType(P, A);
// Noreturn and noexcept adjustment.
if (QualType AdjustedParam; IsFunctionConversion(P, A, AdjustedParam))
P = AdjustedParam;
// FIXME: Compatible calling conventions.
return Context.hasSameFunctionTypeIgnoringExceptionSpec(P, A);
}
/// Get the index of the first template parameter that was originally from the
/// innermost template-parameter-list. This is 0 except when we concatenate
/// the template parameter lists of a class template and a constructor template
/// when forming an implicit deduction guide.
static unsigned getFirstInnerIndex(FunctionTemplateDecl *FTD) {
auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
if (!Guide || !Guide->isImplicit())
return 0;
return Guide->getDeducedTemplate()->getTemplateParameters()->size();
}
/// Determine whether a type denotes a forwarding reference.
static bool isForwardingReference(QualType Param, unsigned FirstInnerIndex) {
// C++1z [temp.deduct.call]p3:
// A forwarding reference is an rvalue reference to a cv-unqualified
// template parameter that does not represent a template parameter of a
// class template.
if (auto *ParamRef = Param->getAs<RValueReferenceType>()) {
if (ParamRef->getPointeeType().getQualifiers())
return false;
auto *TypeParm = ParamRef->getPointeeType()->getAs<TemplateTypeParmType>();
return TypeParm && TypeParm->getIndex() >= FirstInnerIndex;
}
return false;
}
/// Attempt to deduce the template arguments by checking the base types
/// according to (C++20 [temp.deduct.call] p4b3.
///
/// \param S the semantic analysis object within which we are deducing.
///
/// \param RD the top level record object we are deducing against.
///
/// \param TemplateParams the template parameters that we are deducing.
///
/// \param P the template specialization parameter type.
///
/// \param Info information about the template argument deduction itself.
///
/// \param Deduced the deduced template arguments.
///
/// \returns the result of template argument deduction with the bases. "invalid"
/// means no matches, "success" found a single item, and the
/// "MiscellaneousDeductionFailure" result happens when the match is ambiguous.
static TemplateDeductionResult
DeduceTemplateBases(Sema &S, const CXXRecordDecl *RD,
TemplateParameterList *TemplateParams, QualType P,
TemplateDeductionInfo &Info, bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
// C++14 [temp.deduct.call] p4b3:
// If P is a class and P has the form simple-template-id, then the
// transformed A can be a derived class of the deduced A. Likewise if
// P is a pointer to a class of the form simple-template-id, the
// transformed A can be a pointer to a derived class pointed to by the
// deduced A. However, if there is a class C that is a (direct or
// indirect) base class of D and derived (directly or indirectly) from a
// class B and that would be a valid deduced A, the deduced A cannot be
// B or pointer to B, respectively.
//
// These alternatives are considered only if type deduction would
// otherwise fail. If they yield more than one possible deduced A, the
// type deduction fails.
// Use a breadth-first search through the bases to collect the set of
// successful matches. Visited contains the set of nodes we have already
// visited, while ToVisit is our stack of records that we still need to
// visit. Matches contains a list of matches that have yet to be
// disqualified.
llvm::SmallPtrSet<const CXXRecordDecl *, 8> Visited;
SmallVector<QualType, 8> ToVisit;
// We iterate over this later, so we have to use MapVector to ensure
// determinism.
struct MatchValue {
SmallVector<DeducedTemplateArgument, 8> Deduced;
bool HasDeducedAnyParam;
};
llvm::MapVector<const CXXRecordDecl *, MatchValue> Matches;
auto AddBases = [&Visited, &ToVisit](const CXXRecordDecl *RD) {
for (const auto &Base : RD->bases()) {
QualType T = Base.getType();
assert(T->isRecordType() && "Base class that isn't a record?");
if (Visited.insert(T->getAsCXXRecordDecl()).second)
ToVisit.push_back(T);
}
};
// Set up the loop by adding all the bases.
AddBases(RD);
// Search each path of bases until we either run into a successful match
// (where all bases of it are invalid), or we run out of bases.
while (!ToVisit.empty()) {
QualType NextT = ToVisit.pop_back_val();
SmallVector<DeducedTemplateArgument, 8> DeducedCopy(Deduced.begin(),
Deduced.end());
TemplateDeductionInfo BaseInfo(TemplateDeductionInfo::ForBase, Info);
bool HasDeducedAnyParamCopy = false;
TemplateDeductionResult BaseResult = DeduceTemplateSpecArguments(
S, TemplateParams, P, NextT, BaseInfo, PartialOrdering, DeducedCopy,
&HasDeducedAnyParamCopy);
// If this was a successful deduction, add it to the list of matches,
// otherwise we need to continue searching its bases.
const CXXRecordDecl *RD = NextT->getAsCXXRecordDecl();
if (BaseResult == TemplateDeductionResult::Success)
Matches.insert({RD, {DeducedCopy, HasDeducedAnyParamCopy}});
else
AddBases(RD);
}
// At this point, 'Matches' contains a list of seemingly valid bases, however
// in the event that we have more than 1 match, it is possible that the base
// of one of the matches might be disqualified for being a base of another
// valid match. We can count on cyclical instantiations being invalid to
// simplify the disqualifications. That is, if A & B are both matches, and B
// inherits from A (disqualifying A), we know that A cannot inherit from B.
if (Matches.size() > 1) {
Visited.clear();
for (const auto &Match : Matches)
AddBases(Match.first);
// We can give up once we have a single item (or have run out of things to
// search) since cyclical inheritance isn't valid.
while (Matches.size() > 1 && !ToVisit.empty()) {
const CXXRecordDecl *RD = ToVisit.pop_back_val()->getAsCXXRecordDecl();
Matches.erase(RD);
// Always add all bases, since the inheritance tree can contain
// disqualifications for multiple matches.
AddBases(RD);
}
}
if (Matches.empty())
return TemplateDeductionResult::Invalid;
if (Matches.size() > 1)
return TemplateDeductionResult::MiscellaneousDeductionFailure;
std::swap(Matches.front().second.Deduced, Deduced);
if (bool HasDeducedAnyParamCopy = Matches.front().second.HasDeducedAnyParam;
HasDeducedAnyParamCopy && HasDeducedAnyParam)
*HasDeducedAnyParam = HasDeducedAnyParamCopy;
return TemplateDeductionResult::Success;
}
/// When propagating a partial ordering kind into a NonCall context,
/// this is used to downgrade a 'Call' into a 'NonCall', so that
/// the kind still reflects whether we are in a partial ordering context.
static PartialOrderingKind
degradeCallPartialOrderingKind(PartialOrderingKind POK) {
return std::min(POK, PartialOrderingKind::NonCall);
}
/// Deduce the template arguments by comparing the parameter type and
/// the argument type (C++ [temp.deduct.type]).
///
/// \param S the semantic analysis object within which we are deducing
///
/// \param TemplateParams the template parameters that we are deducing
///
/// \param P the parameter type
///
/// \param A the argument type
///
/// \param Info information about the template argument deduction itself
///
/// \param Deduced the deduced template arguments
///
/// \param TDF bitwise OR of the TemplateDeductionFlags bits that describe
/// how template argument deduction is performed.
///
/// \param PartialOrdering Whether we're performing template argument deduction
/// in the context of partial ordering (C++0x [temp.deduct.partial]).
///
/// \returns the result of template argument deduction so far. Note that a
/// "success" result means that template argument deduction has not yet failed,
/// but it may still fail, later, for other reasons.
static TemplateDeductionResult DeduceTemplateArgumentsByTypeMatch(
Sema &S, TemplateParameterList *TemplateParams, QualType P, QualType A,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced, unsigned TDF,
PartialOrderingKind POK, bool DeducedFromArrayBound,
bool *HasDeducedAnyParam) {
// If the argument type is a pack expansion, look at its pattern.
// This isn't explicitly called out
if (const auto *AExp = dyn_cast<PackExpansionType>(A))
A = AExp->getPattern();
assert(!isa<PackExpansionType>(A.getCanonicalType()));
if (POK == PartialOrderingKind::Call) {
// C++11 [temp.deduct.partial]p5:
// Before the partial ordering is done, certain transformations are
// performed on the types used for partial ordering:
// - If P is a reference type, P is replaced by the type referred to.
const ReferenceType *PRef = P->getAs<ReferenceType>();
if (PRef)
P = PRef->getPointeeType();
// - If A is a reference type, A is replaced by the type referred to.
const ReferenceType *ARef = A->getAs<ReferenceType>();
if (ARef)
A = A->getPointeeType();
if (PRef && ARef && S.Context.hasSameUnqualifiedType(P, A)) {
// C++11 [temp.deduct.partial]p9:
// If, for a given type, deduction succeeds in both directions (i.e.,
// the types are identical after the transformations above) and both
// P and A were reference types [...]:
// - if [one type] was an lvalue reference and [the other type] was
// not, [the other type] is not considered to be at least as
// specialized as [the first type]
// - if [one type] is more cv-qualified than [the other type],
// [the other type] is not considered to be at least as specialized
// as [the first type]
// Objective-C ARC adds:
// - [one type] has non-trivial lifetime, [the other type] has
// __unsafe_unretained lifetime, and the types are otherwise
// identical
//
// A is "considered to be at least as specialized" as P iff deduction
// succeeds, so we model this as a deduction failure. Note that
// [the first type] is P and [the other type] is A here; the standard
// gets this backwards.
Qualifiers PQuals = P.getQualifiers(), AQuals = A.getQualifiers();
if ((PRef->isLValueReferenceType() && !ARef->isLValueReferenceType()) ||
PQuals.isStrictSupersetOf(AQuals) ||
(PQuals.hasNonTrivialObjCLifetime() &&
AQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
PQuals.withoutObjCLifetime() == AQuals.withoutObjCLifetime())) {
Info.FirstArg = TemplateArgument(P);
Info.SecondArg = TemplateArgument(A);
return TemplateDeductionResult::NonDeducedMismatch;
}
}
Qualifiers DiscardedQuals;
// C++11 [temp.deduct.partial]p7:
// Remove any top-level cv-qualifiers:
// - If P is a cv-qualified type, P is replaced by the cv-unqualified
// version of P.
P = S.Context.getUnqualifiedArrayType(P, DiscardedQuals);
// - If A is a cv-qualified type, A is replaced by the cv-unqualified
// version of A.
A = S.Context.getUnqualifiedArrayType(A, DiscardedQuals);
} else {
// C++0x [temp.deduct.call]p4 bullet 1:
// - If the original P is a reference type, the deduced A (i.e., the type
// referred to by the reference) can be more cv-qualified than the
// transformed A.
if (TDF & TDF_ParamWithReferenceType) {
Qualifiers Quals;
QualType UnqualP = S.Context.getUnqualifiedArrayType(P, Quals);
Quals.setCVRQualifiers(Quals.getCVRQualifiers() & A.getCVRQualifiers());
P = S.Context.getQualifiedType(UnqualP, Quals);
}
if ((TDF & TDF_TopLevelParameterTypeList) && !P->isFunctionType()) {
// C++0x [temp.deduct.type]p10:
// If P and A are function types that originated from deduction when
// taking the address of a function template (14.8.2.2) or when deducing
// template arguments from a function declaration (14.8.2.6) and Pi and
// Ai are parameters of the top-level parameter-type-list of P and A,
// respectively, Pi is adjusted if it is a forwarding reference and Ai
// is an lvalue reference, in
// which case the type of Pi is changed to be the template parameter
// type (i.e., T&& is changed to simply T). [ Note: As a result, when
// Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
// deduced as X&. - end note ]
TDF &= ~TDF_TopLevelParameterTypeList;
if (isForwardingReference(P, /*FirstInnerIndex=*/0) &&
A->isLValueReferenceType())
P = P->getPointeeType();
}
}
// C++ [temp.deduct.type]p9:
// A template type argument T, a template template argument TT or a
// template non-type argument i can be deduced if P and A have one of
// the following forms:
//
// T
// cv-list T
if (const auto *TTP = P->getAs<TemplateTypeParmType>()) {
// Just skip any attempts to deduce from a placeholder type or a parameter
// at a different depth.
if (A->isPlaceholderType() || Info.getDeducedDepth() != TTP->getDepth())
return TemplateDeductionResult::Success;
unsigned Index = TTP->getIndex();
// If the argument type is an array type, move the qualifiers up to the
// top level, so they can be matched with the qualifiers on the parameter.
if (A->isArrayType()) {
Qualifiers Quals;
A = S.Context.getUnqualifiedArrayType(A, Quals);
if (Quals)
A = S.Context.getQualifiedType(A, Quals);
}
// The argument type can not be less qualified than the parameter
// type.
if (!(TDF & TDF_IgnoreQualifiers) &&
hasInconsistentOrSupersetQualifiersOf(P, A)) {
Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
Info.FirstArg = TemplateArgument(P);
Info.SecondArg = TemplateArgument(A);
return TemplateDeductionResult::Underqualified;
}
// Do not match a function type with a cv-qualified type.
// http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1584
if (A->isFunctionType() && P.hasQualifiers())
return TemplateDeductionResult::NonDeducedMismatch;
assert(TTP->getDepth() == Info.getDeducedDepth() &&
"saw template type parameter with wrong depth");
assert(A->getCanonicalTypeInternal() != S.Context.OverloadTy &&
"Unresolved overloaded function");
QualType DeducedType = A;
// Remove any qualifiers on the parameter from the deduced type.
// We checked the qualifiers for consistency above.
Qualifiers DeducedQs = DeducedType.getQualifiers();
Qualifiers ParamQs = P.getQualifiers();
DeducedQs.removeCVRQualifiers(ParamQs.getCVRQualifiers());
if (ParamQs.hasObjCGCAttr())
DeducedQs.removeObjCGCAttr();
if (ParamQs.hasAddressSpace())
DeducedQs.removeAddressSpace();
if (ParamQs.hasObjCLifetime())
DeducedQs.removeObjCLifetime();
// Objective-C ARC:
// If template deduction would produce a lifetime qualifier on a type
// that is not a lifetime type, template argument deduction fails.
if (ParamQs.hasObjCLifetime() && !DeducedType->isObjCLifetimeType() &&
!DeducedType->isDependentType()) {
Info.Param = cast<TemplateTypeParmDecl>(TemplateParams->getParam(Index));
Info.FirstArg = TemplateArgument(P);
Info.SecondArg = TemplateArgument(A);
return TemplateDeductionResult::Underqualified;
}
// Objective-C ARC:
// If template deduction would produce an argument type with lifetime type
// but no lifetime qualifier, the __strong lifetime qualifier is inferred.
if (S.getLangOpts().ObjCAutoRefCount && DeducedType->isObjCLifetimeType() &&
!DeducedQs.hasObjCLifetime())
DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
DeducedType =
S.Context.getQualifiedType(DeducedType.getUnqualifiedType(), DeducedQs);
DeducedTemplateArgument NewDeduced(DeducedType, DeducedFromArrayBound);
DeducedTemplateArgument Result =
checkDeducedTemplateArguments(S.Context, Deduced[Index], NewDeduced);
if (Result.isNull()) {
// We can also get inconsistencies when matching NTTP type.
switch (NamedDecl *Param = TemplateParams->getParam(Index);
Param->getKind()) {
case Decl::TemplateTypeParm:
Info.Param = cast<TemplateTypeParmDecl>(Param);
break;
case Decl::NonTypeTemplateParm:
Info.Param = cast<NonTypeTemplateParmDecl>(Param);
break;
case Decl::TemplateTemplateParm:
Info.Param = cast<TemplateTemplateParmDecl>(Param);
break;
default:
llvm_unreachable("unexpected kind");
}
Info.FirstArg = Deduced[Index];
Info.SecondArg = NewDeduced;
return TemplateDeductionResult::Inconsistent;
}
Deduced[Index] = Result;
if (HasDeducedAnyParam)
*HasDeducedAnyParam = true;
return TemplateDeductionResult::Success;
}
// Set up the template argument deduction information for a failure.
Info.FirstArg = TemplateArgument(P);
Info.SecondArg = TemplateArgument(A);
// If the parameter is an already-substituted template parameter
// pack, do nothing: we don't know which of its arguments to look
// at, so we have to wait until all of the parameter packs in this
// expansion have arguments.
if (P->getAs<SubstTemplateTypeParmPackType>())
return TemplateDeductionResult::Success;
// Check the cv-qualifiers on the parameter and argument types.
if (!(TDF & TDF_IgnoreQualifiers)) {
if (TDF & TDF_ParamWithReferenceType) {
if (hasInconsistentOrSupersetQualifiersOf(P, A))
return TemplateDeductionResult::NonDeducedMismatch;
} else if (TDF & TDF_ArgWithReferenceType) {
// C++ [temp.deduct.conv]p4:
// If the original A is a reference type, A can be more cv-qualified
// than the deduced A
if (!A.getQualifiers().compatiblyIncludes(P.getQualifiers(),
S.getASTContext()))
return TemplateDeductionResult::NonDeducedMismatch;
// Strip out all extra qualifiers from the argument to figure out the
// type we're converting to, prior to the qualification conversion.
Qualifiers Quals;
A = S.Context.getUnqualifiedArrayType(A, Quals);
A = S.Context.getQualifiedType(A, P.getQualifiers());
} else if (!IsPossiblyOpaquelyQualifiedType(P)) {
if (P.getCVRQualifiers() != A.getCVRQualifiers())
return TemplateDeductionResult::NonDeducedMismatch;
}
}
// If the parameter type is not dependent, there is nothing to deduce.
if (!P->isDependentType()) {
if (TDF & TDF_SkipNonDependent)
return TemplateDeductionResult::Success;
if ((TDF & TDF_IgnoreQualifiers) ? S.Context.hasSameUnqualifiedType(P, A)
: S.Context.hasSameType(P, A))
return TemplateDeductionResult::Success;
if (TDF & TDF_AllowCompatibleFunctionType &&
S.isSameOrCompatibleFunctionType(P, A))
return TemplateDeductionResult::Success;
if (!(TDF & TDF_IgnoreQualifiers))
return TemplateDeductionResult::NonDeducedMismatch;
// Otherwise, when ignoring qualifiers, the types not having the same
// unqualified type does not mean they do not match, so in this case we
// must keep going and analyze with a non-dependent parameter type.
}
switch (P.getCanonicalType()->getTypeClass()) {
// Non-canonical types cannot appear here.
#define NON_CANONICAL_TYPE(Class, Base) \
case Type::Class: llvm_unreachable("deducing non-canonical type: " #Class);
#define TYPE(Class, Base)
#include "clang/AST/TypeNodes.inc"
case Type::TemplateTypeParm:
case Type::SubstTemplateTypeParmPack:
llvm_unreachable("Type nodes handled above");
case Type::Auto:
// C++23 [temp.deduct.funcaddr]/3:
// A placeholder type in the return type of a function template is a
// non-deduced context.
// There's no corresponding wording for [temp.deduct.decl], but we treat
// it the same to match other compilers.
if (P->isDependentType())
return TemplateDeductionResult::Success;
[[fallthrough]];
case Type::Builtin:
case Type::VariableArray:
case Type::Vector:
case Type::FunctionNoProto:
case Type::Record:
case Type::Enum:
case Type::ObjCObject:
case Type::ObjCInterface:
case Type::ObjCObjectPointer:
case Type::BitInt:
return (TDF & TDF_SkipNonDependent) ||
((TDF & TDF_IgnoreQualifiers)
? S.Context.hasSameUnqualifiedType(P, A)
: S.Context.hasSameType(P, A))
? TemplateDeductionResult::Success
: TemplateDeductionResult::NonDeducedMismatch;
// _Complex T [placeholder extension]
case Type::Complex: {
const auto *CP = P->castAs<ComplexType>(), *CA = A->getAs<ComplexType>();
if (!CA)
return TemplateDeductionResult::NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, CP->getElementType(), CA->getElementType(), Info,
Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// _Atomic T [extension]
case Type::Atomic: {
const auto *PA = P->castAs<AtomicType>(), *AA = A->getAs<AtomicType>();
if (!AA)
return TemplateDeductionResult::NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, PA->getValueType(), AA->getValueType(), Info,
Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// T *
case Type::Pointer: {
QualType PointeeType;
if (const auto *PA = A->getAs<PointerType>()) {
PointeeType = PA->getPointeeType();
} else if (const auto *PA = A->getAs<ObjCObjectPointerType>()) {
PointeeType = PA->getPointeeType();
} else {
return TemplateDeductionResult::NonDeducedMismatch;
}
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, P->castAs<PointerType>()->getPointeeType(),
PointeeType, Info, Deduced,
TDF & (TDF_IgnoreQualifiers | TDF_DerivedClass),
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// T &
case Type::LValueReference: {
const auto *RP = P->castAs<LValueReferenceType>(),
*RA = A->getAs<LValueReferenceType>();
if (!RA)
return TemplateDeductionResult::NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, RP->getPointeeType(), RA->getPointeeType(), Info,
Deduced, 0, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// T && [C++0x]
case Type::RValueReference: {
const auto *RP = P->castAs<RValueReferenceType>(),
*RA = A->getAs<RValueReferenceType>();
if (!RA)
return TemplateDeductionResult::NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, RP->getPointeeType(), RA->getPointeeType(), Info,
Deduced, 0, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// T [] (implied, but not stated explicitly)
case Type::IncompleteArray: {
const auto *IAA = S.Context.getAsIncompleteArrayType(A);
if (!IAA)
return TemplateDeductionResult::NonDeducedMismatch;
const auto *IAP = S.Context.getAsIncompleteArrayType(P);
assert(IAP && "Template parameter not of incomplete array type");
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, IAP->getElementType(), IAA->getElementType(), Info,
Deduced, TDF & TDF_IgnoreQualifiers,
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// T [integer-constant]
case Type::ConstantArray: {
const auto *CAA = S.Context.getAsConstantArrayType(A),
*CAP = S.Context.getAsConstantArrayType(P);
assert(CAP);
if (!CAA || CAA->getSize() != CAP->getSize())
return TemplateDeductionResult::NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, CAP->getElementType(), CAA->getElementType(), Info,
Deduced, TDF & TDF_IgnoreQualifiers,
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// type [i]
case Type::DependentSizedArray: {
const auto *AA = S.Context.getAsArrayType(A);
if (!AA)
return TemplateDeductionResult::NonDeducedMismatch;
// Check the element type of the arrays
const auto *DAP = S.Context.getAsDependentSizedArrayType(P);
assert(DAP);
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, DAP->getElementType(), AA->getElementType(),
Info, Deduced, TDF & TDF_IgnoreQualifiers,
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Determine the array bound is something we can deduce.
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, DAP->getSizeExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
// We can perform template argument deduction for the given non-type
// template parameter.
assert(NTTP->getDepth() == Info.getDeducedDepth() &&
"saw non-type template parameter with wrong depth");
if (const auto *CAA = dyn_cast<ConstantArrayType>(AA)) {
llvm::APSInt Size(CAA->getSize());
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, Size, S.Context.getSizeType(),
/*ArrayBound=*/true, Info, POK != PartialOrderingKind::None,
Deduced, HasDeducedAnyParam);
}
if (const auto *DAA = dyn_cast<DependentSizedArrayType>(AA))
if (DAA->getSizeExpr())
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, DAA->getSizeExpr(), Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
// Incomplete type does not match a dependently-sized array type
return TemplateDeductionResult::NonDeducedMismatch;
}
// type(*)(T)
// T(*)()
// T(*)(T)
case Type::FunctionProto: {
const auto *FPP = P->castAs<FunctionProtoType>(),
*FPA = A->getAs<FunctionProtoType>();
if (!FPA)
return TemplateDeductionResult::NonDeducedMismatch;
if (FPP->getMethodQuals() != FPA->getMethodQuals() ||
FPP->getRefQualifier() != FPA->getRefQualifier() ||
FPP->isVariadic() != FPA->isVariadic())
return TemplateDeductionResult::NonDeducedMismatch;
// Check return types.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, FPP->getReturnType(), FPA->getReturnType(),
Info, Deduced, 0, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Check parameter types.
if (auto Result = DeduceTemplateArguments(
S, TemplateParams, FPP->param_types(), FPA->param_types(), Info,
Deduced, TDF & TDF_TopLevelParameterTypeList, POK,
HasDeducedAnyParam,
/*HasDeducedParam=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
if (TDF & TDF_AllowCompatibleFunctionType)
return TemplateDeductionResult::Success;
// FIXME: Per core-2016/10/1019 (no corresponding core issue yet), permit
// deducing through the noexcept-specifier if it's part of the canonical
// type. libstdc++ relies on this.
Expr *NoexceptExpr = FPP->getNoexceptExpr();
if (const NonTypeTemplateParmDecl *NTTP =
NoexceptExpr ? getDeducedParameterFromExpr(Info, NoexceptExpr)
: nullptr) {
assert(NTTP->getDepth() == Info.getDeducedDepth() &&
"saw non-type template parameter with wrong depth");
llvm::APSInt Noexcept(1);
switch (FPA->canThrow()) {
case CT_Cannot:
Noexcept = 1;
[[fallthrough]];
case CT_Can:
// We give E in noexcept(E) the "deduced from array bound" treatment.
// FIXME: Should we?
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, Noexcept, S.Context.BoolTy,
/*DeducedFromArrayBound=*/true, Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
case CT_Dependent:
if (Expr *ArgNoexceptExpr = FPA->getNoexceptExpr())
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, ArgNoexceptExpr, Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
// Can't deduce anything from throw(T...).
break;
}
}
// FIXME: Detect non-deduced exception specification mismatches?
//
// Careful about [temp.deduct.call] and [temp.deduct.conv], which allow
// top-level differences in noexcept-specifications.
return TemplateDeductionResult::Success;
}
case Type::InjectedClassName:
// Treat a template's injected-class-name as if the template
// specialization type had been used.
// template-name<T> (where template-name refers to a class template)
// template-name<i>
// TT<T>
// TT<i>
// TT<>
case Type::TemplateSpecialization: {
// When Arg cannot be a derived class, we can just try to deduce template
// arguments from the template-id.
if (!(TDF & TDF_DerivedClass) || !A->isRecordType())
return DeduceTemplateSpecArguments(S, TemplateParams, P, A, Info,
POK != PartialOrderingKind::None,
Deduced, HasDeducedAnyParam);
SmallVector<DeducedTemplateArgument, 8> DeducedOrig(Deduced.begin(),
Deduced.end());
auto Result = DeduceTemplateSpecArguments(
S, TemplateParams, P, A, Info, POK != PartialOrderingKind::None,
Deduced, HasDeducedAnyParam);
if (Result == TemplateDeductionResult::Success)
return Result;
// We cannot inspect base classes as part of deduction when the type
// is incomplete, so either instantiate any templates necessary to
// complete the type, or skip over it if it cannot be completed.
if (!S.isCompleteType(Info.getLocation(), A))
return Result;
const CXXRecordDecl *RD = A->getAsCXXRecordDecl();
if (RD->isInvalidDecl())
return Result;
// Reset the incorrectly deduced argument from above.
Deduced = DeducedOrig;
// Check bases according to C++14 [temp.deduct.call] p4b3:
auto BaseResult = DeduceTemplateBases(S, RD, TemplateParams, P, Info,
POK != PartialOrderingKind::None,
Deduced, HasDeducedAnyParam);
return BaseResult != TemplateDeductionResult::Invalid ? BaseResult
: Result;
}
// T type::*
// T T::*
// T (type::*)()
// type (T::*)()
// type (type::*)(T)
// type (T::*)(T)
// T (type::*)(T)
// T (T::*)()
// T (T::*)(T)
case Type::MemberPointer: {
const auto *MPP = P->castAs<MemberPointerType>(),
*MPA = A->getAs<MemberPointerType>();
if (!MPA)
return TemplateDeductionResult::NonDeducedMismatch;
QualType PPT = MPP->getPointeeType();
if (PPT->isFunctionType())
S.adjustMemberFunctionCC(PPT, /*HasThisPointer=*/false,
/*IsCtorOrDtor=*/false, Info.getLocation());
QualType APT = MPA->getPointeeType();
if (APT->isFunctionType())
S.adjustMemberFunctionCC(APT, /*HasThisPointer=*/false,
/*IsCtorOrDtor=*/false, Info.getLocation());
unsigned SubTDF = TDF & TDF_IgnoreQualifiers;
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, PPT, APT, Info, Deduced, SubTDF,
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
QualType TP;
if (MPP->isSugared()) {
TP = S.Context.getTypeDeclType(MPP->getMostRecentCXXRecordDecl());
} else {
NestedNameSpecifier *QP = MPP->getQualifier();
if (QP->getKind() == NestedNameSpecifier::Identifier)
// Skip translation if it's a non-deduced context anyway.
return TemplateDeductionResult::Success;
TP = QualType(QP->translateToType(S.Context), 0);
}
assert(!TP.isNull() && "member pointer with non-type class");
QualType TA;
if (MPA->isSugared()) {
TA = S.Context.getTypeDeclType(MPA->getMostRecentCXXRecordDecl());
} else {
NestedNameSpecifier *QA = MPA->getQualifier();
TA = QualType(QA->translateToType(S.Context), 0);
}
assert(!TA.isNull() && "member pointer with non-type class");
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, TP, TA, Info, Deduced, SubTDF,
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// (clang extension)
//
// type(^)(T)
// T(^)()
// T(^)(T)
case Type::BlockPointer: {
const auto *BPP = P->castAs<BlockPointerType>(),
*BPA = A->getAs<BlockPointerType>();
if (!BPA)
return TemplateDeductionResult::NonDeducedMismatch;
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, BPP->getPointeeType(), BPA->getPointeeType(), Info,
Deduced, 0, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
// (clang extension)
//
// T __attribute__(((ext_vector_type(<integral constant>))))
case Type::ExtVector: {
const auto *VP = P->castAs<ExtVectorType>();
QualType ElementType;
if (const auto *VA = A->getAs<ExtVectorType>()) {
// Make sure that the vectors have the same number of elements.
if (VP->getNumElements() != VA->getNumElements())
return TemplateDeductionResult::NonDeducedMismatch;
ElementType = VA->getElementType();
} else if (const auto *VA = A->getAs<DependentSizedExtVectorType>()) {
// We can't check the number of elements, since the argument has a
// dependent number of elements. This can only occur during partial
// ordering.
ElementType = VA->getElementType();
} else {
return TemplateDeductionResult::NonDeducedMismatch;
}
// Perform deduction on the element types.
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, VP->getElementType(), ElementType, Info, Deduced,
TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
case Type::DependentVector: {
const auto *VP = P->castAs<DependentVectorType>();
if (const auto *VA = A->getAs<VectorType>()) {
// Perform deduction on the element types.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, VP->getElementType(), VA->getElementType(),
Info, Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform deduction on the vector size, if we can.
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, VP->getSizeExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
ArgSize = VA->getNumElements();
// Note that we use the "array bound" rules here; just like in that
// case, we don't have any particular type for the vector size, but
// we can provide one if necessary.
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, ArgSize, S.Context.UnsignedIntTy, true,
Info, POK != PartialOrderingKind::None, Deduced,
HasDeducedAnyParam);
}
if (const auto *VA = A->getAs<DependentVectorType>()) {
// Perform deduction on the element types.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, VP->getElementType(), VA->getElementType(),
Info, Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform deduction on the vector size, if we can.
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, VP->getSizeExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, VA->getSizeExpr(), Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
}
return TemplateDeductionResult::NonDeducedMismatch;
}
// (clang extension)
//
// T __attribute__(((ext_vector_type(N))))
case Type::DependentSizedExtVector: {
const auto *VP = P->castAs<DependentSizedExtVectorType>();
if (const auto *VA = A->getAs<ExtVectorType>()) {
// Perform deduction on the element types.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, VP->getElementType(), VA->getElementType(),
Info, Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform deduction on the vector size, if we can.
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, VP->getSizeExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
ArgSize = VA->getNumElements();
// Note that we use the "array bound" rules here; just like in that
// case, we don't have any particular type for the vector size, but
// we can provide one if necessary.
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, ArgSize, S.Context.IntTy, true, Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
}
if (const auto *VA = A->getAs<DependentSizedExtVectorType>()) {
// Perform deduction on the element types.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, VP->getElementType(), VA->getElementType(),
Info, Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform deduction on the vector size, if we can.
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, VP->getSizeExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, VA->getSizeExpr(), Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
}
return TemplateDeductionResult::NonDeducedMismatch;
}
// (clang extension)
//
// T __attribute__((matrix_type(<integral constant>,
// <integral constant>)))
case Type::ConstantMatrix: {
const auto *MP = P->castAs<ConstantMatrixType>(),
*MA = A->getAs<ConstantMatrixType>();
if (!MA)
return TemplateDeductionResult::NonDeducedMismatch;
// Check that the dimensions are the same
if (MP->getNumRows() != MA->getNumRows() ||
MP->getNumColumns() != MA->getNumColumns()) {
return TemplateDeductionResult::NonDeducedMismatch;
}
// Perform deduction on element types.
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, MP->getElementType(), MA->getElementType(), Info,
Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
case Type::DependentSizedMatrix: {
const auto *MP = P->castAs<DependentSizedMatrixType>();
const auto *MA = A->getAs<MatrixType>();
if (!MA)
return TemplateDeductionResult::NonDeducedMismatch;
// Check the element type of the matrixes.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, MP->getElementType(), MA->getElementType(),
Info, Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Try to deduce a matrix dimension.
auto DeduceMatrixArg =
[&S, &Info, &Deduced, &TemplateParams, &HasDeducedAnyParam, POK](
Expr *ParamExpr, const MatrixType *A,
unsigned (ConstantMatrixType::*GetArgDimension)() const,
Expr *(DependentSizedMatrixType::*GetArgDimensionExpr)() const) {
const auto *ACM = dyn_cast<ConstantMatrixType>(A);
const auto *ADM = dyn_cast<DependentSizedMatrixType>(A);
if (!ParamExpr->isValueDependent()) {
std::optional<llvm::APSInt> ParamConst =
ParamExpr->getIntegerConstantExpr(S.Context);
if (!ParamConst)
return TemplateDeductionResult::NonDeducedMismatch;
if (ACM) {
if ((ACM->*GetArgDimension)() == *ParamConst)
return TemplateDeductionResult::Success;
return TemplateDeductionResult::NonDeducedMismatch;
}
Expr *ArgExpr = (ADM->*GetArgDimensionExpr)();
if (std::optional<llvm::APSInt> ArgConst =
ArgExpr->getIntegerConstantExpr(S.Context))
if (*ArgConst == *ParamConst)
return TemplateDeductionResult::Success;
return TemplateDeductionResult::NonDeducedMismatch;
}
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, ParamExpr);
if (!NTTP)
return TemplateDeductionResult::Success;
if (ACM) {
llvm::APSInt ArgConst(
S.Context.getTypeSize(S.Context.getSizeType()));
ArgConst = (ACM->*GetArgDimension)();
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, ArgConst, S.Context.getSizeType(),
/*ArrayBound=*/true, Info, POK != PartialOrderingKind::None,
Deduced, HasDeducedAnyParam);
}
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, (ADM->*GetArgDimensionExpr)(), Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
};
if (auto Result = DeduceMatrixArg(MP->getRowExpr(), MA,
&ConstantMatrixType::getNumRows,
&DependentSizedMatrixType::getRowExpr);
Result != TemplateDeductionResult::Success)
return Result;
return DeduceMatrixArg(MP->getColumnExpr(), MA,
&ConstantMatrixType::getNumColumns,
&DependentSizedMatrixType::getColumnExpr);
}
// (clang extension)
//
// T __attribute__(((address_space(N))))
case Type::DependentAddressSpace: {
const auto *ASP = P->castAs<DependentAddressSpaceType>();
if (const auto *ASA = A->getAs<DependentAddressSpaceType>()) {
// Perform deduction on the pointer type.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, ASP->getPointeeType(), ASA->getPointeeType(),
Info, Deduced, TDF, degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform deduction on the address space, if we can.
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, ASP->getAddrSpaceExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, ASA->getAddrSpaceExpr(), Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
}
if (isTargetAddressSpace(A.getAddressSpace())) {
llvm::APSInt ArgAddressSpace(S.Context.getTypeSize(S.Context.IntTy),
false);
ArgAddressSpace = toTargetAddressSpace(A.getAddressSpace());
// Perform deduction on the pointer types.
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, ASP->getPointeeType(),
S.Context.removeAddrSpaceQualType(A), Info, Deduced, TDF,
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
// Perform deduction on the address space, if we can.
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, ASP->getAddrSpaceExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, ArgAddressSpace, S.Context.IntTy, true,
Info, POK != PartialOrderingKind::None, Deduced,
HasDeducedAnyParam);
}
return TemplateDeductionResult::NonDeducedMismatch;
}
case Type::DependentBitInt: {
const auto *IP = P->castAs<DependentBitIntType>();
if (const auto *IA = A->getAs<BitIntType>()) {
if (IP->isUnsigned() != IA->isUnsigned())
return TemplateDeductionResult::NonDeducedMismatch;
const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, IP->getNumBitsExpr());
if (!NTTP)
return TemplateDeductionResult::Success;
llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
ArgSize = IA->getNumBits();
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, ArgSize, S.Context.IntTy, true, Info,
POK != PartialOrderingKind::None, Deduced, HasDeducedAnyParam);
}
if (const auto *IA = A->getAs<DependentBitIntType>()) {
if (IP->isUnsigned() != IA->isUnsigned())
return TemplateDeductionResult::NonDeducedMismatch;
return TemplateDeductionResult::Success;
}
return TemplateDeductionResult::NonDeducedMismatch;
}
case Type::TypeOfExpr:
case Type::TypeOf:
case Type::DependentName:
case Type::UnresolvedUsing:
case Type::Decltype:
case Type::UnaryTransform:
case Type::DeducedTemplateSpecialization:
case Type::DependentTemplateSpecialization:
case Type::PackExpansion:
case Type::Pipe:
case Type::ArrayParameter:
case Type::HLSLAttributedResource:
// No template argument deduction for these types
return TemplateDeductionResult::Success;
case Type::PackIndexing: {
const PackIndexingType *PIT = P->getAs<PackIndexingType>();
if (PIT->hasSelectedType()) {
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, PIT->getSelectedType(), A, Info, Deduced, TDF,
degradeCallPartialOrderingKind(POK),
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
}
return TemplateDeductionResult::IncompletePack;
}
}
llvm_unreachable("Invalid Type Class!");
}
static TemplateDeductionResult
DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
const TemplateArgument &P, TemplateArgument A,
TemplateDeductionInfo &Info, bool PartialOrdering,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool *HasDeducedAnyParam) {
// If the template argument is a pack expansion, perform template argument
// deduction against the pattern of that expansion. This only occurs during
// partial ordering.
if (A.isPackExpansion())
A = A.getPackExpansionPattern();
switch (P.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Null template argument in parameter list");
case TemplateArgument::Type:
if (A.getKind() == TemplateArgument::Type)
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, P.getAsType(), A.getAsType(), Info, Deduced, 0,
PartialOrdering ? PartialOrderingKind::NonCall
: PartialOrderingKind::None,
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
case TemplateArgument::Template:
// PartialOrdering does not matter here, since template specializations are
// not being deduced.
if (A.getKind() == TemplateArgument::Template)
return DeduceTemplateArguments(
S, TemplateParams, P.getAsTemplate(), A.getAsTemplate(), Info,
/*DefaultArguments=*/{}, /*PartialOrdering=*/false, Deduced,
HasDeducedAnyParam);
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
case TemplateArgument::TemplateExpansion:
llvm_unreachable("caller should handle pack expansions");
case TemplateArgument::Declaration:
if (A.getKind() == TemplateArgument::Declaration &&
isSameDeclaration(P.getAsDecl(), A.getAsDecl()))
return TemplateDeductionResult::Success;
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
case TemplateArgument::NullPtr:
// 'nullptr' has only one possible value, so it always matches.
if (A.getKind() == TemplateArgument::NullPtr)
return TemplateDeductionResult::Success;
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
case TemplateArgument::Integral:
if (A.getKind() == TemplateArgument::Integral) {
if (hasSameExtendedValue(P.getAsIntegral(), A.getAsIntegral()))
return TemplateDeductionResult::Success;
}
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
case TemplateArgument::StructuralValue:
// FIXME: structural equality will also compare types,
// but they should match iff they have the same value.
if (A.getKind() == TemplateArgument::StructuralValue &&
A.structurallyEquals(P))
return TemplateDeductionResult::Success;
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
case TemplateArgument::Expression:
if (const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, P.getAsExpr())) {
switch (A.getKind()) {
case TemplateArgument::Expression: {
const Expr *E = A.getAsExpr();
// When checking NTTP, if either the parameter or the argument is
// dependent, as there would be otherwise nothing to deduce, we force
// the argument to the parameter type using this dependent implicit
// cast, in order to maintain invariants. Now we can deduce the
// resulting type from the original type, and deduce the original type
// against the parameter we are checking.
if (const auto *ICE = dyn_cast<ImplicitCastExpr>(E);
ICE && ICE->getCastKind() == clang::CK_Dependent) {
E = ICE->getSubExpr();
if (auto Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, ICE->getType(), E->getType(), Info,
Deduced, TDF_SkipNonDependent,
PartialOrdering ? PartialOrderingKind::NonCall
: PartialOrderingKind::None,
/*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
}
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, DeducedTemplateArgument(A), E->getType(),
Info, PartialOrdering, Deduced, HasDeducedAnyParam);
}
case TemplateArgument::Integral:
case TemplateArgument::StructuralValue:
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, DeducedTemplateArgument(A),
A.getNonTypeTemplateArgumentType(), Info, PartialOrdering, Deduced,
HasDeducedAnyParam);
case TemplateArgument::NullPtr:
return DeduceNullPtrTemplateArgument(
S, TemplateParams, NTTP, A.getNullPtrType(), Info, PartialOrdering,
Deduced, HasDeducedAnyParam);
case TemplateArgument::Declaration:
return DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, A.getAsDecl(), A.getParamTypeForDecl(),
Info, PartialOrdering, Deduced, HasDeducedAnyParam);
case TemplateArgument::Null:
case TemplateArgument::Type:
case TemplateArgument::Template:
case TemplateArgument::TemplateExpansion:
case TemplateArgument::Pack:
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
}
llvm_unreachable("Unknown template argument kind");
}
// Can't deduce anything, but that's okay.
return TemplateDeductionResult::Success;
case TemplateArgument::Pack:
llvm_unreachable("Argument packs should be expanded by the caller!");
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
/// Determine whether there is a template argument to be used for
/// deduction.
///
/// This routine "expands" argument packs in-place, overriding its input
/// parameters so that \c Args[ArgIdx] will be the available template argument.
///
/// \returns true if there is another template argument (which will be at
/// \c Args[ArgIdx]), false otherwise.
static bool hasTemplateArgumentForDeduction(ArrayRef<TemplateArgument> &Args,
unsigned &ArgIdx) {
if (ArgIdx == Args.size())
return false;
const TemplateArgument &Arg = Args[ArgIdx];
if (Arg.getKind() != TemplateArgument::Pack)
return true;
assert(ArgIdx == Args.size() - 1 && "Pack not at the end of argument list?");
Args = Arg.pack_elements();
ArgIdx = 0;
return ArgIdx < Args.size();
}
/// Determine whether the given set of template arguments has a pack
/// expansion that is not the last template argument.
static bool hasPackExpansionBeforeEnd(ArrayRef<TemplateArgument> Args) {
bool FoundPackExpansion = false;
for (const auto &A : Args) {
if (FoundPackExpansion)
return true;
if (A.getKind() == TemplateArgument::Pack)
return hasPackExpansionBeforeEnd(A.pack_elements());
// FIXME: If this is a fixed-arity pack expansion from an outer level of
// templates, it should not be treated as a pack expansion.
if (A.isPackExpansion())
FoundPackExpansion = true;
}
return false;
}
static TemplateDeductionResult
DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
ArrayRef<TemplateArgument> Ps,
ArrayRef<TemplateArgument> As,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool NumberOfArgumentsMustMatch, bool PartialOrdering,
PackFold PackFold, bool *HasDeducedAnyParam) {
bool FoldPackParameter = PackFold == PackFold::ParameterToArgument ||
PackFold == PackFold::Both,
FoldPackArgument = PackFold == PackFold::ArgumentToParameter ||
PackFold == PackFold::Both;
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (FoldPackParameter && hasPackExpansionBeforeEnd(Ps))
return TemplateDeductionResult::Success;
// C++0x [temp.deduct.type]p9:
// If P has a form that contains <T> or <i>, then each argument Pi of the
// respective template argument list P is compared with the corresponding
// argument Ai of the corresponding template argument list of A.
for (unsigned ArgIdx = 0, ParamIdx = 0; /**/; /**/) {
if (!hasTemplateArgumentForDeduction(Ps, ParamIdx))
return !FoldPackParameter && hasTemplateArgumentForDeduction(As, ArgIdx)
? TemplateDeductionResult::MiscellaneousDeductionFailure
: TemplateDeductionResult::Success;
if (!Ps[ParamIdx].isPackExpansion()) {
// The simple case: deduce template arguments by matching Pi and Ai.
// Check whether we have enough arguments.
if (!hasTemplateArgumentForDeduction(As, ArgIdx))
return !FoldPackArgument && NumberOfArgumentsMustMatch
? TemplateDeductionResult::MiscellaneousDeductionFailure
: TemplateDeductionResult::Success;
if (As[ArgIdx].isPackExpansion()) {
// C++1z [temp.deduct.type]p9:
// During partial ordering, if Ai was originally a pack expansion
// [and] Pi is not a pack expansion, template argument deduction
// fails.
if (!FoldPackArgument)
return TemplateDeductionResult::MiscellaneousDeductionFailure;
TemplateArgument Pattern = As[ArgIdx].getPackExpansionPattern();
for (;;) {
// Deduce template parameters from the pattern.
if (auto Result = DeduceTemplateArguments(
S, TemplateParams, Ps[ParamIdx], Pattern, Info,
PartialOrdering, Deduced, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
++ParamIdx;
if (!hasTemplateArgumentForDeduction(Ps, ParamIdx))
return TemplateDeductionResult::Success;
if (Ps[ParamIdx].isPackExpansion())
break;
}
} else {
// Perform deduction for this Pi/Ai pair.
if (auto Result = DeduceTemplateArguments(
S, TemplateParams, Ps[ParamIdx], As[ArgIdx], Info,
PartialOrdering, Deduced, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
++ArgIdx;
++ParamIdx;
continue;
}
}
// The parameter is a pack expansion.
// C++0x [temp.deduct.type]p9:
// If Pi is a pack expansion, then the pattern of Pi is compared with
// each remaining argument in the template argument list of A. Each
// comparison deduces template arguments for subsequent positions in the
// template parameter packs expanded by Pi.
TemplateArgument Pattern = Ps[ParamIdx].getPackExpansionPattern();
// Prepare to deduce the packs within the pattern.
PackDeductionScope PackScope(S, TemplateParams, Deduced, Info, Pattern);
// Keep track of the deduced template arguments for each parameter pack
// expanded by this pack expansion (the outer index) and for each
// template argument (the inner SmallVectors).
for (; hasTemplateArgumentForDeduction(As, ArgIdx) &&
PackScope.hasNextElement();
++ArgIdx) {
if (!As[ArgIdx].isPackExpansion()) {
if (!FoldPackParameter)
return TemplateDeductionResult::MiscellaneousDeductionFailure;
if (FoldPackArgument)
Info.setStrictPackMatch();
}
// Deduce template arguments from the pattern.
if (auto Result = DeduceTemplateArguments(
S, TemplateParams, Pattern, As[ArgIdx], Info, PartialOrdering,
Deduced, HasDeducedAnyParam);
Result != TemplateDeductionResult::Success)
return Result;
PackScope.nextPackElement();
}
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
return PackScope.finish();
}
}
TemplateDeductionResult Sema::DeduceTemplateArguments(
TemplateParameterList *TemplateParams, ArrayRef<TemplateArgument> Ps,
ArrayRef<TemplateArgument> As, sema::TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
bool NumberOfArgumentsMustMatch) {
return ::DeduceTemplateArguments(
*this, TemplateParams, Ps, As, Info, Deduced, NumberOfArgumentsMustMatch,
/*PartialOrdering=*/false, PackFold::ParameterToArgument,
/*HasDeducedAnyParam=*/nullptr);
}
/// Determine whether two template arguments are the same.
static bool isSameTemplateArg(ASTContext &Context,
TemplateArgument X,
const TemplateArgument &Y,
bool PartialOrdering,
bool PackExpansionMatchesPack = false) {
// If we're checking deduced arguments (X) against original arguments (Y),
// we will have flattened packs to non-expansions in X.
if (PackExpansionMatchesPack && X.isPackExpansion() && !Y.isPackExpansion())
X = X.getPackExpansionPattern();
if (X.getKind() != Y.getKind())
return false;
switch (X.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Comparing NULL template argument");
case TemplateArgument::Type:
return Context.getCanonicalType(X.getAsType()) ==
Context.getCanonicalType(Y.getAsType());
case TemplateArgument::Declaration:
return isSameDeclaration(X.getAsDecl(), Y.getAsDecl());
case TemplateArgument::NullPtr:
return Context.hasSameType(X.getNullPtrType(), Y.getNullPtrType());
case TemplateArgument::Template:
case TemplateArgument::TemplateExpansion:
return Context.getCanonicalTemplateName(
X.getAsTemplateOrTemplatePattern()).getAsVoidPointer() ==
Context.getCanonicalTemplateName(
Y.getAsTemplateOrTemplatePattern()).getAsVoidPointer();
case TemplateArgument::Integral:
return hasSameExtendedValue(X.getAsIntegral(), Y.getAsIntegral());
case TemplateArgument::StructuralValue:
return X.structurallyEquals(Y);
case TemplateArgument::Expression: {
llvm::FoldingSetNodeID XID, YID;
X.getAsExpr()->Profile(XID, Context, true);
Y.getAsExpr()->Profile(YID, Context, true);
return XID == YID;
}
case TemplateArgument::Pack: {
unsigned PackIterationSize = X.pack_size();
if (X.pack_size() != Y.pack_size()) {
if (!PartialOrdering)
return false;
// C++0x [temp.deduct.type]p9:
// During partial ordering, if Ai was originally a pack expansion:
// - if P does not contain a template argument corresponding to Ai
// then Ai is ignored;
bool XHasMoreArg = X.pack_size() > Y.pack_size();
if (!(XHasMoreArg && X.pack_elements().back().isPackExpansion()) &&
!(!XHasMoreArg && Y.pack_elements().back().isPackExpansion()))
return false;
if (XHasMoreArg)
PackIterationSize = Y.pack_size();
}
ArrayRef<TemplateArgument> XP = X.pack_elements();
ArrayRef<TemplateArgument> YP = Y.pack_elements();
for (unsigned i = 0; i < PackIterationSize; ++i)
if (!isSameTemplateArg(Context, XP[i], YP[i], PartialOrdering,
PackExpansionMatchesPack))
return false;
return true;
}
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
TemplateArgumentLoc
Sema::getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
QualType NTTPType, SourceLocation Loc,
NamedDecl *TemplateParam) {
switch (Arg.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Can't get a NULL template argument here");
case TemplateArgument::Type:
return TemplateArgumentLoc(
Arg, Context.getTrivialTypeSourceInfo(Arg.getAsType(), Loc));
case TemplateArgument::Declaration: {
if (NTTPType.isNull())
NTTPType = Arg.getParamTypeForDecl();
Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc,
TemplateParam)
.getAs<Expr>();
return TemplateArgumentLoc(TemplateArgument(E), E);
}
case TemplateArgument::NullPtr: {
if (NTTPType.isNull())
NTTPType = Arg.getNullPtrType();
Expr *E = BuildExpressionFromDeclTemplateArgument(Arg, NTTPType, Loc)
.getAs<Expr>();
return TemplateArgumentLoc(TemplateArgument(NTTPType, /*isNullPtr*/true),
E);
}
case TemplateArgument::Integral:
case TemplateArgument::StructuralValue: {
Expr *E = BuildExpressionFromNonTypeTemplateArgument(Arg, Loc).get();
return TemplateArgumentLoc(TemplateArgument(E), E);
}
case TemplateArgument::Template:
case TemplateArgument::TemplateExpansion: {
NestedNameSpecifierLocBuilder Builder;
TemplateName Template = Arg.getAsTemplateOrTemplatePattern();
if (DependentTemplateName *DTN = Template.getAsDependentTemplateName())
Builder.MakeTrivial(Context, DTN->getQualifier(), Loc);
else if (QualifiedTemplateName *QTN =
Template.getAsQualifiedTemplateName())
Builder.MakeTrivial(Context, QTN->getQualifier(), Loc);
if (Arg.getKind() == TemplateArgument::Template)
return TemplateArgumentLoc(Context, Arg,
Builder.getWithLocInContext(Context), Loc);
return TemplateArgumentLoc(
Context, Arg, Builder.getWithLocInContext(Context), Loc, Loc);
}
case TemplateArgument::Expression:
return TemplateArgumentLoc(Arg, Arg.getAsExpr());
case TemplateArgument::Pack:
return TemplateArgumentLoc(Arg, TemplateArgumentLocInfo());
}
llvm_unreachable("Invalid TemplateArgument Kind!");
}
TemplateArgumentLoc
Sema::getIdentityTemplateArgumentLoc(NamedDecl *TemplateParm,
SourceLocation Location) {
return getTrivialTemplateArgumentLoc(
Context.getInjectedTemplateArg(TemplateParm), QualType(), Location);
}
/// Convert the given deduced template argument and add it to the set of
/// fully-converted template arguments.
static bool
ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
DeducedTemplateArgument Arg, NamedDecl *Template,
TemplateDeductionInfo &Info, bool IsDeduced,
Sema::CheckTemplateArgumentInfo &CTAI) {
auto ConvertArg = [&](DeducedTemplateArgument Arg,
unsigned ArgumentPackIndex) {
// Convert the deduced template argument into a template
// argument that we can check, almost as if the user had written
// the template argument explicitly.
TemplateArgumentLoc ArgLoc = S.getTrivialTemplateArgumentLoc(
Arg, QualType(), Info.getLocation(), Param);
SaveAndRestore _1(CTAI.MatchingTTP, false);
SaveAndRestore _2(CTAI.StrictPackMatch, false);
// Check the template argument, converting it as necessary.
auto Res = S.CheckTemplateArgument(
Param, ArgLoc, Template, Template->getLocation(),
Template->getSourceRange().getEnd(), ArgumentPackIndex, CTAI,
IsDeduced
? (Arg.wasDeducedFromArrayBound() ? Sema::CTAK_DeducedFromArrayBound
: Sema::CTAK_Deduced)
: Sema::CTAK_Specified);
if (CTAI.StrictPackMatch)
Info.setStrictPackMatch();
return Res;
};
if (Arg.getKind() == TemplateArgument::Pack) {
// This is a template argument pack, so check each of its arguments against
// the template parameter.
SmallVector<TemplateArgument, 2> SugaredPackedArgsBuilder,
CanonicalPackedArgsBuilder;
for (const auto &P : Arg.pack_elements()) {
// When converting the deduced template argument, append it to the
// general output list. We need to do this so that the template argument
// checking logic has all of the prior template arguments available.
DeducedTemplateArgument InnerArg(P);
InnerArg.setDeducedFromArrayBound(Arg.wasDeducedFromArrayBound());
assert(InnerArg.getKind() != TemplateArgument::Pack &&
"deduced nested pack");
if (P.isNull()) {
// We deduced arguments for some elements of this pack, but not for
// all of them. This happens if we get a conditionally-non-deduced
// context in a pack expansion (such as an overload set in one of the
// arguments).
S.Diag(Param->getLocation(),
diag::err_template_arg_deduced_incomplete_pack)
<< Arg << Param;
return true;
}
if (ConvertArg(InnerArg, SugaredPackedArgsBuilder.size()))
return true;
// Move the converted template argument into our argument pack.
SugaredPackedArgsBuilder.push_back(CTAI.SugaredConverted.pop_back_val());
CanonicalPackedArgsBuilder.push_back(
CTAI.CanonicalConverted.pop_back_val());
}
// If the pack is empty, we still need to substitute into the parameter
// itself, in case that substitution fails.
if (SugaredPackedArgsBuilder.empty()) {
LocalInstantiationScope Scope(S);
MultiLevelTemplateArgumentList Args(Template, CTAI.SugaredConverted,
/*Final=*/true);
if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
NTTP, CTAI.SugaredConverted,
Template->getSourceRange());
if (Inst.isInvalid() ||
S.SubstType(NTTP->getType(), Args, NTTP->getLocation(),
NTTP->getDeclName()).isNull())
return true;
} else if (auto *TTP = dyn_cast<TemplateTemplateParmDecl>(Param)) {
Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
TTP, CTAI.SugaredConverted,
Template->getSourceRange());
if (Inst.isInvalid() || !S.SubstDecl(TTP, S.CurContext, Args))
return true;
}
// For type parameters, no substitution is ever required.
}
// Create the resulting argument pack.
CTAI.SugaredConverted.push_back(
TemplateArgument::CreatePackCopy(S.Context, SugaredPackedArgsBuilder));
CTAI.CanonicalConverted.push_back(TemplateArgument::CreatePackCopy(
S.Context, CanonicalPackedArgsBuilder));
return false;
}
return ConvertArg(Arg, 0);
}
// FIXME: This should not be a template, but
// ClassTemplatePartialSpecializationDecl sadly does not derive from
// TemplateDecl.
/// \param IsIncomplete When used, we only consider template parameters that
/// were deduced, disregarding any default arguments. After the function
/// finishes, the object pointed at will contain a value indicating if the
/// conversion was actually incomplete.
template <typename TemplateDeclT>
static TemplateDeductionResult ConvertDeducedTemplateArguments(
Sema &S, TemplateDeclT *Template, bool IsDeduced,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info, Sema::CheckTemplateArgumentInfo &CTAI,
LocalInstantiationScope *CurrentInstantiationScope,
unsigned NumAlreadyConverted, bool *IsIncomplete) {
TemplateParameterList *TemplateParams = Template->getTemplateParameters();
for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
NamedDecl *Param = TemplateParams->getParam(I);
// C++0x [temp.arg.explicit]p3:
// A trailing template parameter pack (14.5.3) not otherwise deduced will
// be deduced to an empty sequence of template arguments.
// FIXME: Where did the word "trailing" come from?
if (Deduced[I].isNull() && Param->isTemplateParameterPack()) {
if (auto Result =
PackDeductionScope(S, TemplateParams, Deduced, Info, I).finish();
Result != TemplateDeductionResult::Success)
return Result;
}
if (!Deduced[I].isNull()) {
if (I < NumAlreadyConverted) {
// We may have had explicitly-specified template arguments for a
// template parameter pack (that may or may not have been extended
// via additional deduced arguments).
if (Param->isParameterPack() && CurrentInstantiationScope &&
CurrentInstantiationScope->getPartiallySubstitutedPack() == Param) {
// Forget the partially-substituted pack; its substitution is now
// complete.
CurrentInstantiationScope->ResetPartiallySubstitutedPack();
// We still need to check the argument in case it was extended by
// deduction.
} else {
// We have already fully type-checked and converted this
// argument, because it was explicitly-specified. Just record the
// presence of this argument.
CTAI.SugaredConverted.push_back(Deduced[I]);
CTAI.CanonicalConverted.push_back(
S.Context.getCanonicalTemplateArgument(Deduced[I]));
continue;
}
}
// We may have deduced this argument, so it still needs to be
// checked and converted.
if (ConvertDeducedTemplateArgument(S, Param, Deduced[I], Template, Info,
IsDeduced, CTAI)) {
Info.Param = makeTemplateParameter(Param);
// FIXME: These template arguments are temporary. Free them!
Info.reset(
TemplateArgumentList::CreateCopy(S.Context, CTAI.SugaredConverted),
TemplateArgumentList::CreateCopy(S.Context,
CTAI.CanonicalConverted));
return TemplateDeductionResult::SubstitutionFailure;
}
continue;
}
// [C++26][temp.deduct.partial]p12 - When partial ordering, it's ok for
// template parameters to remain not deduced. As a provisional fix for a
// core issue that does not exist yet, which may be related to CWG2160, only
// consider template parameters that were deduced, disregarding any default
// arguments.
if (IsIncomplete) {
*IsIncomplete = true;
CTAI.SugaredConverted.push_back({});
CTAI.CanonicalConverted.push_back({});
continue;
}
// Substitute into the default template argument, if available.
bool HasDefaultArg = false;
TemplateDecl *TD = dyn_cast<TemplateDecl>(Template);
if (!TD) {
assert(isa<ClassTemplatePartialSpecializationDecl>(Template) ||
isa<VarTemplatePartialSpecializationDecl>(Template));
return TemplateDeductionResult::Incomplete;
}
TemplateArgumentLoc DefArg;
{
Qualifiers ThisTypeQuals;
CXXRecordDecl *ThisContext = nullptr;
if (auto *Rec = dyn_cast<CXXRecordDecl>(TD->getDeclContext()))
if (Rec->isLambda())
if (auto *Method = dyn_cast<CXXMethodDecl>(Rec->getDeclContext())) {
ThisContext = Method->getParent();
ThisTypeQuals = Method->getMethodQualifiers();
}
Sema::CXXThisScopeRAII ThisScope(S, ThisContext, ThisTypeQuals,
S.getLangOpts().CPlusPlus17);
DefArg = S.SubstDefaultTemplateArgumentIfAvailable(
TD, TD->getLocation(), TD->getSourceRange().getEnd(), Param,
CTAI.SugaredConverted, CTAI.CanonicalConverted, HasDefaultArg);
}
// If there was no default argument, deduction is incomplete.
if (DefArg.getArgument().isNull()) {
Info.Param = makeTemplateParameter(
const_cast<NamedDecl *>(TemplateParams->getParam(I)));
Info.reset(
TemplateArgumentList::CreateCopy(S.Context, CTAI.SugaredConverted),
TemplateArgumentList::CreateCopy(S.Context, CTAI.CanonicalConverted));
return HasDefaultArg ? TemplateDeductionResult::SubstitutionFailure
: TemplateDeductionResult::Incomplete;
}
SaveAndRestore _1(CTAI.PartialOrdering, false);
SaveAndRestore _2(CTAI.MatchingTTP, false);
SaveAndRestore _3(CTAI.StrictPackMatch, false);
// Check whether we can actually use the default argument.
if (S.CheckTemplateArgument(
Param, DefArg, TD, TD->getLocation(), TD->getSourceRange().getEnd(),
/*ArgumentPackIndex=*/0, CTAI, Sema::CTAK_Specified)) {
Info.Param = makeTemplateParameter(
const_cast<NamedDecl *>(TemplateParams->getParam(I)));
// FIXME: These template arguments are temporary. Free them!
Info.reset(
TemplateArgumentList::CreateCopy(S.Context, CTAI.SugaredConverted),
TemplateArgumentList::CreateCopy(S.Context, CTAI.CanonicalConverted));
return TemplateDeductionResult::SubstitutionFailure;
}
// If we get here, we successfully used the default template argument.
}
return TemplateDeductionResult::Success;
}
static DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
if (auto *DC = dyn_cast<DeclContext>(D))
return DC;
return D->getDeclContext();
}
template<typename T> struct IsPartialSpecialization {
static constexpr bool value = false;
};
template<>
struct IsPartialSpecialization<ClassTemplatePartialSpecializationDecl> {
static constexpr bool value = true;
};
template<>
struct IsPartialSpecialization<VarTemplatePartialSpecializationDecl> {
static constexpr bool value = true;
};
template <typename TemplateDeclT>
static bool DeducedArgsNeedReplacement(TemplateDeclT *Template) {
return false;
}
template <>
bool DeducedArgsNeedReplacement<VarTemplatePartialSpecializationDecl>(
VarTemplatePartialSpecializationDecl *Spec) {
return !Spec->isClassScopeExplicitSpecialization();
}
template <>
bool DeducedArgsNeedReplacement<ClassTemplatePartialSpecializationDecl>(
ClassTemplatePartialSpecializationDecl *Spec) {
return !Spec->isClassScopeExplicitSpecialization();
}
template <typename TemplateDeclT>
static TemplateDeductionResult
CheckDeducedArgumentConstraints(Sema &S, TemplateDeclT *Template,
ArrayRef<TemplateArgument> SugaredDeducedArgs,
ArrayRef<TemplateArgument> CanonicalDeducedArgs,
TemplateDeductionInfo &Info) {
llvm::SmallVector<const Expr *, 3> AssociatedConstraints;
Template->getAssociatedConstraints(AssociatedConstraints);
std::optional<ArrayRef<TemplateArgument>> Innermost;
// If we don't need to replace the deduced template arguments,
// we can add them immediately as the inner-most argument list.
if (!DeducedArgsNeedReplacement(Template))
Innermost = CanonicalDeducedArgs;
MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
Template, Template->getDeclContext(), /*Final=*/false, Innermost,
/*RelativeToPrimary=*/true, /*Pattern=*/
nullptr, /*ForConstraintInstantiation=*/true);
// getTemplateInstantiationArgs picks up the non-deduced version of the
// template args when this is a variable template partial specialization and
// not class-scope explicit specialization, so replace with Deduced Args
// instead of adding to inner-most.
if (!Innermost)
MLTAL.replaceInnermostTemplateArguments(Template, CanonicalDeducedArgs);
if (S.CheckConstraintSatisfaction(Template, AssociatedConstraints, MLTAL,
Info.getLocation(),
Info.AssociatedConstraintsSatisfaction) ||
!Info.AssociatedConstraintsSatisfaction.IsSatisfied) {
Info.reset(
TemplateArgumentList::CreateCopy(S.Context, SugaredDeducedArgs),
TemplateArgumentList::CreateCopy(S.Context, CanonicalDeducedArgs));
return TemplateDeductionResult::ConstraintsNotSatisfied;
}
return TemplateDeductionResult::Success;
}
/// Complete template argument deduction for a partial specialization.
template <typename T>
static std::enable_if_t<IsPartialSpecialization<T>::value,
TemplateDeductionResult>
FinishTemplateArgumentDeduction(
Sema &S, T *Partial, bool IsPartialOrdering,
ArrayRef<TemplateArgument> TemplateArgs,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info) {
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
S, Sema::ExpressionEvaluationContext::Unevaluated);
Sema::SFINAETrap Trap(S);
Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Partial));
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
Sema::CheckTemplateArgumentInfo CTAI(IsPartialOrdering);
if (auto Result = ConvertDeducedTemplateArguments(
S, Partial, IsPartialOrdering, Deduced, Info, CTAI,
/*CurrentInstantiationScope=*/nullptr, /*NumAlreadyConverted=*/0,
/*IsIncomplete=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
// Form the template argument list from the deduced template arguments.
TemplateArgumentList *SugaredDeducedArgumentList =
TemplateArgumentList::CreateCopy(S.Context, CTAI.SugaredConverted);
TemplateArgumentList *CanonicalDeducedArgumentList =
TemplateArgumentList::CreateCopy(S.Context, CTAI.CanonicalConverted);
Info.reset(SugaredDeducedArgumentList, CanonicalDeducedArgumentList);
// Substitute the deduced template arguments into the template
// arguments of the class template partial specialization, and
// verify that the instantiated template arguments are both valid
// and are equivalent to the template arguments originally provided
// to the class template.
LocalInstantiationScope InstScope(S);
auto *Template = Partial->getSpecializedTemplate();
const ASTTemplateArgumentListInfo *PartialTemplArgInfo =
Partial->getTemplateArgsAsWritten();
TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
PartialTemplArgInfo->RAngleLoc);
if (S.SubstTemplateArguments(
PartialTemplArgInfo->arguments(),
MultiLevelTemplateArgumentList(Partial, CTAI.SugaredConverted,
/*Final=*/true),
InstArgs)) {
unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
if (ParamIdx >= Partial->getTemplateParameters()->size())
ParamIdx = Partial->getTemplateParameters()->size() - 1;
Decl *Param = const_cast<NamedDecl *>(
Partial->getTemplateParameters()->getParam(ParamIdx));
Info.Param = makeTemplateParameter(Param);
Info.FirstArg = (*PartialTemplArgInfo)[ArgIdx].getArgument();
return TemplateDeductionResult::SubstitutionFailure;
}
bool ConstraintsNotSatisfied;
Sema::CheckTemplateArgumentInfo InstCTAI;
if (S.CheckTemplateArgumentList(Template, Partial->getLocation(), InstArgs,
/*DefaultArgs=*/{}, false, InstCTAI,
/*UpdateArgsWithConversions=*/true,
&ConstraintsNotSatisfied))
return ConstraintsNotSatisfied
? TemplateDeductionResult::ConstraintsNotSatisfied
: TemplateDeductionResult::SubstitutionFailure;
TemplateParameterList *TemplateParams = Template->getTemplateParameters();
for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
TemplateArgument InstArg = InstCTAI.SugaredConverted.data()[I];
if (!isSameTemplateArg(S.Context, TemplateArgs[I], InstArg,
IsPartialOrdering)) {
Info.Param = makeTemplateParameter(TemplateParams->getParam(I));
Info.FirstArg = TemplateArgs[I];
Info.SecondArg = InstArg;
return TemplateDeductionResult::NonDeducedMismatch;
}
}
if (Trap.hasErrorOccurred())
return TemplateDeductionResult::SubstitutionFailure;
if (!IsPartialOrdering) {
if (auto Result = CheckDeducedArgumentConstraints(
S, Partial, CTAI.SugaredConverted, CTAI.CanonicalConverted, Info);
Result != TemplateDeductionResult::Success)
return Result;
}
return TemplateDeductionResult::Success;
}
/// Complete template argument deduction for a class or variable template,
/// when partial ordering against a partial specialization.
// FIXME: Factor out duplication with partial specialization version above.
static TemplateDeductionResult FinishTemplateArgumentDeduction(
Sema &S, TemplateDecl *Template, bool PartialOrdering,
ArrayRef<TemplateArgument> TemplateArgs,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info) {
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
S, Sema::ExpressionEvaluationContext::Unevaluated);
Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Template));
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
Sema::CheckTemplateArgumentInfo CTAI(PartialOrdering);
if (auto Result = ConvertDeducedTemplateArguments(
S, Template, /*IsDeduced=*/PartialOrdering, Deduced, Info, CTAI,
/*CurrentInstantiationScope=*/nullptr,
/*NumAlreadyConverted=*/0U, /*IsIncomplete=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
// Check that we produced the correct argument list.
SmallVector<ArrayRef<TemplateArgument>, 4> PsStack{TemplateArgs},
AsStack{CTAI.CanonicalConverted};
for (;;) {
auto take = [](SmallVectorImpl<ArrayRef<TemplateArgument>> &Stack)
-> std::tuple<ArrayRef<TemplateArgument> &, TemplateArgument> {
while (!Stack.empty()) {
auto &Xs = Stack.back();
if (Xs.empty()) {
Stack.pop_back();
continue;
}
auto &X = Xs.front();
if (X.getKind() == TemplateArgument::Pack) {
Stack.emplace_back(X.getPackAsArray());
Xs = Xs.drop_front();
continue;
}
assert(!X.isNull());
return {Xs, X};
}
static constexpr ArrayRef<TemplateArgument> None;
return {const_cast<ArrayRef<TemplateArgument> &>(None),
TemplateArgument()};
};
auto [Ps, P] = take(PsStack);
auto [As, A] = take(AsStack);
if (P.isNull() && A.isNull())
break;
TemplateArgument PP = P.isPackExpansion() ? P.getPackExpansionPattern() : P,
PA = A.isPackExpansion() ? A.getPackExpansionPattern() : A;
if (!isSameTemplateArg(S.Context, PP, PA, /*PartialOrdering=*/false)) {
if (!P.isPackExpansion() && !A.isPackExpansion()) {
Info.Param =
makeTemplateParameter(Template->getTemplateParameters()->getParam(
(AsStack.empty() ? CTAI.CanonicalConverted.end()
: AsStack.front().begin()) -
1 - CTAI.CanonicalConverted.begin()));
Info.FirstArg = P;
Info.SecondArg = A;
return TemplateDeductionResult::NonDeducedMismatch;
}
if (P.isPackExpansion()) {
Ps = Ps.drop_front();
continue;
}
if (A.isPackExpansion()) {
As = As.drop_front();
continue;
}
}
Ps = Ps.drop_front(P.isPackExpansion() ? 0 : 1);
As = As.drop_front(A.isPackExpansion() && !P.isPackExpansion() ? 0 : 1);
}
assert(PsStack.empty());
assert(AsStack.empty());
if (!PartialOrdering) {
if (auto Result = CheckDeducedArgumentConstraints(
S, Template, CTAI.SugaredConverted, CTAI.CanonicalConverted, Info);
Result != TemplateDeductionResult::Success)
return Result;
}
return TemplateDeductionResult::Success;
}
/// Complete template argument deduction for DeduceTemplateArgumentsFromType.
/// FIXME: this is mostly duplicated with the above two versions. Deduplicate
/// the three implementations.
static TemplateDeductionResult FinishTemplateArgumentDeduction(
Sema &S, TemplateDecl *TD,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info) {
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
S, Sema::ExpressionEvaluationContext::Unevaluated);
Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(TD));
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
Sema::CheckTemplateArgumentInfo CTAI;
if (auto Result = ConvertDeducedTemplateArguments(
S, TD, /*IsDeduced=*/false, Deduced, Info, CTAI,
/*CurrentInstantiationScope=*/nullptr, /*NumAlreadyConverted=*/0,
/*IsIncomplete=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
return ::CheckDeducedArgumentConstraints(S, TD, CTAI.SugaredConverted,
CTAI.CanonicalConverted, Info);
}
/// Perform template argument deduction to determine whether the given template
/// arguments match the given class or variable template partial specialization
/// per C++ [temp.class.spec.match].
template <typename T>
static std::enable_if_t<IsPartialSpecialization<T>::value,
TemplateDeductionResult>
DeduceTemplateArguments(Sema &S, T *Partial,
ArrayRef<TemplateArgument> TemplateArgs,
TemplateDeductionInfo &Info) {
if (Partial->isInvalidDecl())
return TemplateDeductionResult::Invalid;
// C++ [temp.class.spec.match]p2:
// A partial specialization matches a given actual template
// argument list if the template arguments of the partial
// specialization can be deduced from the actual template argument
// list (14.8.2).
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
S, Sema::ExpressionEvaluationContext::Unevaluated);
Sema::SFINAETrap Trap(S);
// This deduction has no relation to any outer instantiation we might be
// performing.
LocalInstantiationScope InstantiationScope(S);
SmallVector<DeducedTemplateArgument, 4> Deduced;
Deduced.resize(Partial->getTemplateParameters()->size());
if (TemplateDeductionResult Result = ::DeduceTemplateArguments(
S, Partial->getTemplateParameters(),
Partial->getTemplateArgs().asArray(), TemplateArgs, Info, Deduced,
/*NumberOfArgumentsMustMatch=*/false, /*PartialOrdering=*/false,
PackFold::ParameterToArgument,
/*HasDeducedAnyParam=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
Sema::InstantiatingTemplate Inst(S, Info.getLocation(), Partial, DeducedArgs,
Info);
if (Inst.isInvalid())
return TemplateDeductionResult::InstantiationDepth;
TemplateDeductionResult Result;
S.runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = ::FinishTemplateArgumentDeduction(S, Partial,
/*IsPartialOrdering=*/false,
TemplateArgs, Deduced, Info);
});
if (Result != TemplateDeductionResult::Success)
return Result;
if (Trap.hasErrorOccurred())
return TemplateDeductionResult::SubstitutionFailure;
return TemplateDeductionResult::Success;
}
TemplateDeductionResult
Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
ArrayRef<TemplateArgument> TemplateArgs,
TemplateDeductionInfo &Info) {
return ::DeduceTemplateArguments(*this, Partial, TemplateArgs, Info);
}
TemplateDeductionResult
Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
ArrayRef<TemplateArgument> TemplateArgs,
TemplateDeductionInfo &Info) {
return ::DeduceTemplateArguments(*this, Partial, TemplateArgs, Info);
}
TemplateDeductionResult
Sema::DeduceTemplateArgumentsFromType(TemplateDecl *TD, QualType FromType,
sema::TemplateDeductionInfo &Info) {
if (TD->isInvalidDecl())
return TemplateDeductionResult::Invalid;
QualType PType;
if (const auto *CTD = dyn_cast<ClassTemplateDecl>(TD)) {
// Use the InjectedClassNameType.
PType = Context.getTypeDeclType(CTD->getTemplatedDecl());
} else if (const auto *AliasTemplate = dyn_cast<TypeAliasTemplateDecl>(TD)) {
PType = AliasTemplate->getTemplatedDecl()->getUnderlyingType();
} else {
assert(false && "Expected a class or alias template");
}
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
*this, Sema::ExpressionEvaluationContext::Unevaluated);
SFINAETrap Trap(*this);
// This deduction has no relation to any outer instantiation we might be
// performing.
LocalInstantiationScope InstantiationScope(*this);
SmallVector<DeducedTemplateArgument> Deduced(
TD->getTemplateParameters()->size());
SmallVector<TemplateArgument> PArgs = {TemplateArgument(PType)};
SmallVector<TemplateArgument> AArgs = {TemplateArgument(FromType)};
if (auto DeducedResult = DeduceTemplateArguments(
TD->getTemplateParameters(), PArgs, AArgs, Info, Deduced, false);
DeducedResult != TemplateDeductionResult::Success) {
return DeducedResult;
}
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
InstantiatingTemplate Inst(*this, Info.getLocation(), TD, DeducedArgs, Info);
if (Inst.isInvalid())
return TemplateDeductionResult::InstantiationDepth;
TemplateDeductionResult Result;
runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = ::FinishTemplateArgumentDeduction(*this, TD, Deduced, Info);
});
if (Result != TemplateDeductionResult::Success)
return Result;
if (Trap.hasErrorOccurred())
return TemplateDeductionResult::SubstitutionFailure;
return TemplateDeductionResult::Success;
}
/// Determine whether the given type T is a simple-template-id type.
static bool isSimpleTemplateIdType(QualType T) {
if (const TemplateSpecializationType *Spec
= T->getAs<TemplateSpecializationType>())
return Spec->getTemplateName().getAsTemplateDecl() != nullptr;
// C++17 [temp.local]p2:
// the injected-class-name [...] is equivalent to the template-name followed
// by the template-arguments of the class template specialization or partial
// specialization enclosed in <>
// ... which means it's equivalent to a simple-template-id.
//
// This only arises during class template argument deduction for a copy
// deduction candidate, where it permits slicing.
if (T->getAs<InjectedClassNameType>())
return true;
return false;
}
TemplateDeductionResult Sema::SubstituteExplicitTemplateArguments(
FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo &ExplicitTemplateArgs,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
SmallVectorImpl<QualType> &ParamTypes, QualType *FunctionType,
TemplateDeductionInfo &Info) {
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
if (ExplicitTemplateArgs.size() == 0) {
// No arguments to substitute; just copy over the parameter types and
// fill in the function type.
for (auto *P : Function->parameters())
ParamTypes.push_back(P->getType());
if (FunctionType)
*FunctionType = Function->getType();
return TemplateDeductionResult::Success;
}
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
*this, Sema::ExpressionEvaluationContext::Unevaluated);
SFINAETrap Trap(*this);
// C++ [temp.arg.explicit]p3:
// Template arguments that are present shall be specified in the
// declaration order of their corresponding template-parameters. The
// template argument list shall not specify more template-arguments than
// there are corresponding template-parameters.
// Enter a new template instantiation context where we check the
// explicitly-specified template arguments against this function template,
// and then substitute them into the function parameter types.
SmallVector<TemplateArgument, 4> DeducedArgs;
InstantiatingTemplate Inst(
*this, Info.getLocation(), FunctionTemplate, DeducedArgs,
CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
if (Inst.isInvalid())
return TemplateDeductionResult::InstantiationDepth;
CheckTemplateArgumentInfo CTAI;
if (CheckTemplateArgumentList(FunctionTemplate, SourceLocation(),
ExplicitTemplateArgs, /*DefaultArgs=*/{},
/*PartialTemplateArgs=*/true, CTAI,
/*UpdateArgsWithConversions=*/false) ||
Trap.hasErrorOccurred()) {
unsigned Index = CTAI.SugaredConverted.size();
if (Index >= TemplateParams->size())
return TemplateDeductionResult::SubstitutionFailure;
Info.Param = makeTemplateParameter(TemplateParams->getParam(Index));
return TemplateDeductionResult::InvalidExplicitArguments;
}
// Form the template argument list from the explicitly-specified
// template arguments.
TemplateArgumentList *SugaredExplicitArgumentList =
TemplateArgumentList::CreateCopy(Context, CTAI.SugaredConverted);
TemplateArgumentList *CanonicalExplicitArgumentList =
TemplateArgumentList::CreateCopy(Context, CTAI.CanonicalConverted);
Info.setExplicitArgs(SugaredExplicitArgumentList,
CanonicalExplicitArgumentList);
// Template argument deduction and the final substitution should be
// done in the context of the templated declaration. Explicit
// argument substitution, on the other hand, needs to happen in the
// calling context.
ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
// If we deduced template arguments for a template parameter pack,
// note that the template argument pack is partially substituted and record
// the explicit template arguments. They'll be used as part of deduction
// for this template parameter pack.
unsigned PartiallySubstitutedPackIndex = -1u;
if (!CTAI.SugaredConverted.empty()) {
const TemplateArgument &Arg = CTAI.SugaredConverted.back();
if (Arg.getKind() == TemplateArgument::Pack) {
auto *Param = TemplateParams->getParam(CTAI.SugaredConverted.size() - 1);
// If this is a fully-saturated fixed-size pack, it should be
// fully-substituted, not partially-substituted.
std::optional<unsigned> Expansions = getExpandedPackSize(Param);
if (!Expansions || Arg.pack_size() < *Expansions) {
PartiallySubstitutedPackIndex = CTAI.SugaredConverted.size() - 1;
CurrentInstantiationScope->SetPartiallySubstitutedPack(
Param, Arg.pack_begin(), Arg.pack_size());
}
}
}
const FunctionProtoType *Proto
= Function->getType()->getAs<FunctionProtoType>();
assert(Proto && "Function template does not have a prototype?");
// Isolate our substituted parameters from our caller.
LocalInstantiationScope InstScope(*this, /*MergeWithOuterScope*/true);
ExtParameterInfoBuilder ExtParamInfos;
MultiLevelTemplateArgumentList MLTAL(FunctionTemplate,
SugaredExplicitArgumentList->asArray(),
/*Final=*/true);
// Instantiate the types of each of the function parameters given the
// explicitly-specified template arguments. If the function has a trailing
// return type, substitute it after the arguments to ensure we substitute
// in lexical order.
if (Proto->hasTrailingReturn()) {
if (SubstParmTypes(Function->getLocation(), Function->parameters(),
Proto->getExtParameterInfosOrNull(), MLTAL, ParamTypes,
/*params=*/nullptr, ExtParamInfos))
return TemplateDeductionResult::SubstitutionFailure;
}
// Instantiate the return type.
QualType ResultType;
{
// C++11 [expr.prim.general]p3:
// If a declaration declares a member function or member function
// template of a class X, the expression this is a prvalue of type
// "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
// and the end of the function-definition, member-declarator, or
// declarator.
Qualifiers ThisTypeQuals;
CXXRecordDecl *ThisContext = nullptr;
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
ThisContext = Method->getParent();
ThisTypeQuals = Method->getMethodQualifiers();
}
CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
getLangOpts().CPlusPlus11);
ResultType =
SubstType(Proto->getReturnType(), MLTAL,
Function->getTypeSpecStartLoc(), Function->getDeclName());
if (ResultType.isNull() || Trap.hasErrorOccurred())
return TemplateDeductionResult::SubstitutionFailure;
// CUDA: Kernel function must have 'void' return type.
if (getLangOpts().CUDA)
if (Function->hasAttr<CUDAGlobalAttr>() && !ResultType->isVoidType()) {
Diag(Function->getLocation(), diag::err_kern_type_not_void_return)
<< Function->getType() << Function->getSourceRange();
return TemplateDeductionResult::SubstitutionFailure;
}
}
// Instantiate the types of each of the function parameters given the
// explicitly-specified template arguments if we didn't do so earlier.
if (!Proto->hasTrailingReturn() &&
SubstParmTypes(Function->getLocation(), Function->parameters(),
Proto->getExtParameterInfosOrNull(), MLTAL, ParamTypes,
/*params*/ nullptr, ExtParamInfos))
return TemplateDeductionResult::SubstitutionFailure;
if (FunctionType) {
auto EPI = Proto->getExtProtoInfo();
EPI.ExtParameterInfos = ExtParamInfos.getPointerOrNull(ParamTypes.size());
*FunctionType = BuildFunctionType(ResultType, ParamTypes,
Function->getLocation(),
Function->getDeclName(),
EPI);
if (FunctionType->isNull() || Trap.hasErrorOccurred())
return TemplateDeductionResult::SubstitutionFailure;
}
// C++ [temp.arg.explicit]p2:
// Trailing template arguments that can be deduced (14.8.2) may be
// omitted from the list of explicit template-arguments. If all of the
// template arguments can be deduced, they may all be omitted; in this
// case, the empty template argument list <> itself may also be omitted.
//
// Take all of the explicitly-specified arguments and put them into
// the set of deduced template arguments. The partially-substituted
// parameter pack, however, will be set to NULL since the deduction
// mechanism handles the partially-substituted argument pack directly.
Deduced.reserve(TemplateParams->size());
for (unsigned I = 0, N = SugaredExplicitArgumentList->size(); I != N; ++I) {
const TemplateArgument &Arg = SugaredExplicitArgumentList->get(I);
if (I == PartiallySubstitutedPackIndex)
Deduced.push_back(DeducedTemplateArgument());
else
Deduced.push_back(Arg);
}
return TemplateDeductionResult::Success;
}
/// Check whether the deduced argument type for a call to a function
/// template matches the actual argument type per C++ [temp.deduct.call]p4.
static TemplateDeductionResult
CheckOriginalCallArgDeduction(Sema &S, TemplateDeductionInfo &Info,
Sema::OriginalCallArg OriginalArg,
QualType DeducedA) {
ASTContext &Context = S.Context;
auto Failed = [&]() -> TemplateDeductionResult {
Info.FirstArg = TemplateArgument(DeducedA);
Info.SecondArg = TemplateArgument(OriginalArg.OriginalArgType);
Info.CallArgIndex = OriginalArg.ArgIdx;
return OriginalArg.DecomposedParam
? TemplateDeductionResult::DeducedMismatchNested
: TemplateDeductionResult::DeducedMismatch;
};
QualType A = OriginalArg.OriginalArgType;
QualType OriginalParamType = OriginalArg.OriginalParamType;
// Check for type equality (top-level cv-qualifiers are ignored).
if (Context.hasSameUnqualifiedType(A, DeducedA))
return TemplateDeductionResult::Success;
// Strip off references on the argument types; they aren't needed for
// the following checks.
if (const ReferenceType *DeducedARef = DeducedA->getAs<ReferenceType>())
DeducedA = DeducedARef->getPointeeType();
if (const ReferenceType *ARef = A->getAs<ReferenceType>())
A = ARef->getPointeeType();
// C++ [temp.deduct.call]p4:
// [...] However, there are three cases that allow a difference:
// - If the original P is a reference type, the deduced A (i.e., the
// type referred to by the reference) can be more cv-qualified than
// the transformed A.
if (const ReferenceType *OriginalParamRef
= OriginalParamType->getAs<ReferenceType>()) {
// We don't want to keep the reference around any more.
OriginalParamType = OriginalParamRef->getPointeeType();
// FIXME: Resolve core issue (no number yet): if the original P is a
// reference type and the transformed A is function type "noexcept F",
// the deduced A can be F.
QualType Tmp;
if (A->isFunctionType() && S.IsFunctionConversion(A, DeducedA, Tmp))
return TemplateDeductionResult::Success;
Qualifiers AQuals = A.getQualifiers();
Qualifiers DeducedAQuals = DeducedA.getQualifiers();
// Under Objective-C++ ARC, the deduced type may have implicitly
// been given strong or (when dealing with a const reference)
// unsafe_unretained lifetime. If so, update the original
// qualifiers to include this lifetime.
if (S.getLangOpts().ObjCAutoRefCount &&
((DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_Strong &&
AQuals.getObjCLifetime() == Qualifiers::OCL_None) ||
(DeducedAQuals.hasConst() &&
DeducedAQuals.getObjCLifetime() == Qualifiers::OCL_ExplicitNone))) {
AQuals.setObjCLifetime(DeducedAQuals.getObjCLifetime());
}
if (AQuals == DeducedAQuals) {
// Qualifiers match; there's nothing to do.
} else if (!DeducedAQuals.compatiblyIncludes(AQuals, S.getASTContext())) {
return Failed();
} else {
// Qualifiers are compatible, so have the argument type adopt the
// deduced argument type's qualifiers as if we had performed the
// qualification conversion.
A = Context.getQualifiedType(A.getUnqualifiedType(), DeducedAQuals);
}
}
// - The transformed A can be another pointer or pointer to member
// type that can be converted to the deduced A via a function pointer
// conversion and/or a qualification conversion.
//
// Also allow conversions which merely strip __attribute__((noreturn)) from
// function types (recursively).
bool ObjCLifetimeConversion = false;
QualType ResultTy;
if ((A->isAnyPointerType() || A->isMemberPointerType()) &&
(S.IsQualificationConversion(A, DeducedA, false,
ObjCLifetimeConversion) ||
S.IsFunctionConversion(A, DeducedA, ResultTy)))
return TemplateDeductionResult::Success;
// - If P is a class and P has the form simple-template-id, then the
// transformed A can be a derived class of the deduced A. [...]
// [...] Likewise, if P is a pointer to a class of the form
// simple-template-id, the transformed A can be a pointer to a
// derived class pointed to by the deduced A.
if (const PointerType *OriginalParamPtr
= OriginalParamType->getAs<PointerType>()) {
if (const PointerType *DeducedAPtr = DeducedA->getAs<PointerType>()) {
if (const PointerType *APtr = A->getAs<PointerType>()) {
if (A->getPointeeType()->isRecordType()) {
OriginalParamType = OriginalParamPtr->getPointeeType();
DeducedA = DeducedAPtr->getPointeeType();
A = APtr->getPointeeType();
}
}
}
}
if (Context.hasSameUnqualifiedType(A, DeducedA))
return TemplateDeductionResult::Success;
if (A->isRecordType() && isSimpleTemplateIdType(OriginalParamType) &&
S.IsDerivedFrom(Info.getLocation(), A, DeducedA))
return TemplateDeductionResult::Success;
return Failed();
}
/// Find the pack index for a particular parameter index in an instantiation of
/// a function template with specific arguments.
///
/// \return The pack index for whichever pack produced this parameter, or -1
/// if this was not produced by a parameter. Intended to be used as the
/// ArgumentPackSubstitutionIndex for further substitutions.
// FIXME: We should track this in OriginalCallArgs so we don't need to
// reconstruct it here.
static unsigned getPackIndexForParam(Sema &S,
FunctionTemplateDecl *FunctionTemplate,
const MultiLevelTemplateArgumentList &Args,
unsigned ParamIdx) {
unsigned Idx = 0;
for (auto *PD : FunctionTemplate->getTemplatedDecl()->parameters()) {
if (PD->isParameterPack()) {
unsigned NumExpansions =
S.getNumArgumentsInExpansion(PD->getType(), Args).value_or(1);
if (Idx + NumExpansions > ParamIdx)
return ParamIdx - Idx;
Idx += NumExpansions;
} else {
if (Idx == ParamIdx)
return -1; // Not a pack expansion
++Idx;
}
}
llvm_unreachable("parameter index would not be produced from template");
}
// if `Specialization` is a `CXXConstructorDecl` or `CXXConversionDecl`,
// we'll try to instantiate and update its explicit specifier after constraint
// checking.
static TemplateDeductionResult instantiateExplicitSpecifierDeferred(
Sema &S, FunctionDecl *Specialization,
const MultiLevelTemplateArgumentList &SubstArgs,
TemplateDeductionInfo &Info, FunctionTemplateDecl *FunctionTemplate,
ArrayRef<TemplateArgument> DeducedArgs) {
auto GetExplicitSpecifier = [](FunctionDecl *D) {
return isa<CXXConstructorDecl>(D)
? cast<CXXConstructorDecl>(D)->getExplicitSpecifier()
: cast<CXXConversionDecl>(D)->getExplicitSpecifier();
};
auto SetExplicitSpecifier = [](FunctionDecl *D, ExplicitSpecifier ES) {
isa<CXXConstructorDecl>(D)
? cast<CXXConstructorDecl>(D)->setExplicitSpecifier(ES)
: cast<CXXConversionDecl>(D)->setExplicitSpecifier(ES);
};
ExplicitSpecifier ES = GetExplicitSpecifier(Specialization);
Expr *ExplicitExpr = ES.getExpr();
if (!ExplicitExpr)
return TemplateDeductionResult::Success;
if (!ExplicitExpr->isValueDependent())
return TemplateDeductionResult::Success;
Sema::InstantiatingTemplate Inst(
S, Info.getLocation(), FunctionTemplate, DeducedArgs,
Sema::CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
if (Inst.isInvalid())
return TemplateDeductionResult::InstantiationDepth;
Sema::SFINAETrap Trap(S);
const ExplicitSpecifier InstantiatedES =
S.instantiateExplicitSpecifier(SubstArgs, ES);
if (InstantiatedES.isInvalid() || Trap.hasErrorOccurred()) {
Specialization->setInvalidDecl(true);
return TemplateDeductionResult::SubstitutionFailure;
}
SetExplicitSpecifier(Specialization, InstantiatedES);
return TemplateDeductionResult::Success;
}
TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
FunctionTemplateDecl *FunctionTemplate,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
unsigned NumExplicitlySpecified, FunctionDecl *&Specialization,
TemplateDeductionInfo &Info,
SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
bool PartialOverloading, bool PartialOrdering,
llvm::function_ref<bool()> CheckNonDependent) {
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
*this, Sema::ExpressionEvaluationContext::Unevaluated);
SFINAETrap Trap(*this);
// Enter a new template instantiation context while we instantiate the
// actual function declaration.
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
InstantiatingTemplate Inst(
*this, Info.getLocation(), FunctionTemplate, DeducedArgs,
CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
if (Inst.isInvalid())
return TemplateDeductionResult::InstantiationDepth;
ContextRAII SavedContext(*this, FunctionTemplate->getTemplatedDecl());
// C++ [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
bool IsIncomplete = false;
CheckTemplateArgumentInfo CTAI(PartialOrdering);
if (auto Result = ConvertDeducedTemplateArguments(
*this, FunctionTemplate, /*IsDeduced=*/true, Deduced, Info, CTAI,
CurrentInstantiationScope, NumExplicitlySpecified,
PartialOverloading ? &IsIncomplete : nullptr);
Result != TemplateDeductionResult::Success)
return Result;
// C++ [temp.deduct.call]p10: [DR1391]
// If deduction succeeds for all parameters that contain
// template-parameters that participate in template argument deduction,
// and all template arguments are explicitly specified, deduced, or
// obtained from default template arguments, remaining parameters are then
// compared with the corresponding arguments. For each remaining parameter
// P with a type that was non-dependent before substitution of any
// explicitly-specified template arguments, if the corresponding argument
// A cannot be implicitly converted to P, deduction fails.
if (CheckNonDependent())
return TemplateDeductionResult::NonDependentConversionFailure;
// Form the template argument list from the deduced template arguments.
TemplateArgumentList *SugaredDeducedArgumentList =
TemplateArgumentList::CreateCopy(Context, CTAI.SugaredConverted);
TemplateArgumentList *CanonicalDeducedArgumentList =
TemplateArgumentList::CreateCopy(Context, CTAI.CanonicalConverted);
Info.reset(SugaredDeducedArgumentList, CanonicalDeducedArgumentList);
// Substitute the deduced template arguments into the function template
// declaration to produce the function template specialization.
DeclContext *Owner = FunctionTemplate->getDeclContext();
if (FunctionTemplate->getFriendObjectKind())
Owner = FunctionTemplate->getLexicalDeclContext();
FunctionDecl *FD = FunctionTemplate->getTemplatedDecl();
MultiLevelTemplateArgumentList SubstArgs(
FunctionTemplate, CanonicalDeducedArgumentList->asArray(),
/*Final=*/false);
Specialization = cast_or_null<FunctionDecl>(
SubstDecl(FD, Owner, SubstArgs));
if (!Specialization || Specialization->isInvalidDecl())
return TemplateDeductionResult::SubstitutionFailure;
assert(isSameDeclaration(Specialization->getPrimaryTemplate(),
FunctionTemplate));
// If the template argument list is owned by the function template
// specialization, release it.
if (Specialization->getTemplateSpecializationArgs() ==
CanonicalDeducedArgumentList &&
!Trap.hasErrorOccurred())
Info.takeCanonical();
// There may have been an error that did not prevent us from constructing a
// declaration. Mark the declaration invalid and return with a substitution
// failure.
if (Trap.hasErrorOccurred()) {
Specialization->setInvalidDecl(true);
return TemplateDeductionResult::SubstitutionFailure;
}
// C++2a [temp.deduct]p5
// [...] When all template arguments have been deduced [...] all uses of
// template parameters [...] are replaced with the corresponding deduced
// or default argument values.
// [...] If the function template has associated constraints
// ([temp.constr.decl]), those constraints are checked for satisfaction
// ([temp.constr.constr]). If the constraints are not satisfied, type
// deduction fails.
if (!IsIncomplete) {
if (CheckInstantiatedFunctionTemplateConstraints(
Info.getLocation(), Specialization, CTAI.CanonicalConverted,
Info.AssociatedConstraintsSatisfaction))
return TemplateDeductionResult::MiscellaneousDeductionFailure;
if (!Info.AssociatedConstraintsSatisfaction.IsSatisfied) {
Info.reset(Info.takeSugared(), TemplateArgumentList::CreateCopy(
Context, CTAI.CanonicalConverted));
return TemplateDeductionResult::ConstraintsNotSatisfied;
}
}
// We skipped the instantiation of the explicit-specifier during the
// substitution of `FD` before. So, we try to instantiate it back if
// `Specialization` is either a constructor or a conversion function.
if (isa<CXXConstructorDecl, CXXConversionDecl>(Specialization)) {
if (TemplateDeductionResult::Success !=
instantiateExplicitSpecifierDeferred(*this, Specialization, SubstArgs,
Info, FunctionTemplate,
DeducedArgs)) {
return TemplateDeductionResult::SubstitutionFailure;
}
}
if (OriginalCallArgs) {
// C++ [temp.deduct.call]p4:
// In general, the deduction process attempts to find template argument
// values that will make the deduced A identical to A (after the type A
// is transformed as described above). [...]
llvm::SmallDenseMap<std::pair<unsigned, QualType>, QualType> DeducedATypes;
for (unsigned I = 0, N = OriginalCallArgs->size(); I != N; ++I) {
OriginalCallArg OriginalArg = (*OriginalCallArgs)[I];
auto ParamIdx = OriginalArg.ArgIdx;
unsigned ExplicitOffset =
Specialization->hasCXXExplicitFunctionObjectParameter() ? 1 : 0;
if (ParamIdx >= Specialization->getNumParams() - ExplicitOffset)
// FIXME: This presumably means a pack ended up smaller than we
// expected while deducing. Should this not result in deduction
// failure? Can it even happen?
continue;
QualType DeducedA;
if (!OriginalArg.DecomposedParam) {
// P is one of the function parameters, just look up its substituted
// type.
DeducedA =
Specialization->getParamDecl(ParamIdx + ExplicitOffset)->getType();
} else {
// P is a decomposed element of a parameter corresponding to a
// braced-init-list argument. Substitute back into P to find the
// deduced A.
QualType &CacheEntry =
DeducedATypes[{ParamIdx, OriginalArg.OriginalParamType}];
if (CacheEntry.isNull()) {
ArgumentPackSubstitutionIndexRAII PackIndex(
*this, getPackIndexForParam(*this, FunctionTemplate, SubstArgs,
ParamIdx));
CacheEntry =
SubstType(OriginalArg.OriginalParamType, SubstArgs,
Specialization->getTypeSpecStartLoc(),
Specialization->getDeclName());
}
DeducedA = CacheEntry;
}
if (auto TDK =
CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA);
TDK != TemplateDeductionResult::Success)
return TDK;
}
}
// If we suppressed any diagnostics while performing template argument
// deduction, and if we haven't already instantiated this declaration,
// keep track of these diagnostics. They'll be emitted if this specialization
// is actually used.
if (Info.diag_begin() != Info.diag_end()) {
auto [Pos, Inserted] =
SuppressedDiagnostics.try_emplace(Specialization->getCanonicalDecl());
if (Inserted)
Pos->second.append(Info.diag_begin(), Info.diag_end());
}
return TemplateDeductionResult::Success;
}
/// Gets the type of a function for template-argument-deducton
/// purposes when it's considered as part of an overload set.
static QualType GetTypeOfFunction(Sema &S, const OverloadExpr::FindResult &R,
FunctionDecl *Fn) {
// We may need to deduce the return type of the function now.
if (S.getLangOpts().CPlusPlus14 && Fn->getReturnType()->isUndeducedType() &&
S.DeduceReturnType(Fn, R.Expression->getExprLoc(), /*Diagnose*/ false))
return {};
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Fn))
if (Method->isImplicitObjectMemberFunction()) {
// An instance method that's referenced in a form that doesn't
// look like a member pointer is just invalid.
if (!R.HasFormOfMemberPointer)
return {};
return S.Context.getMemberPointerType(
Fn->getType(), /*Qualifier=*/nullptr, Method->getParent());
}
if (!R.IsAddressOfOperand) return Fn->getType();
return S.Context.getPointerType(Fn->getType());
}
/// Apply the deduction rules for overload sets.
///
/// \return the null type if this argument should be treated as an
/// undeduced context
static QualType
ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
Expr *Arg, QualType ParamType,
bool ParamWasReference,
TemplateSpecCandidateSet *FailedTSC = nullptr) {
OverloadExpr::FindResult R = OverloadExpr::find(Arg);
OverloadExpr *Ovl = R.Expression;
// C++0x [temp.deduct.call]p4
unsigned TDF = 0;
if (ParamWasReference)
TDF |= TDF_ParamWithReferenceType;
if (R.IsAddressOfOperand)
TDF |= TDF_IgnoreQualifiers;
// C++0x [temp.deduct.call]p6:
// When P is a function type, pointer to function type, or pointer
// to member function type:
if (!ParamType->isFunctionType() &&
!ParamType->isFunctionPointerType() &&
!ParamType->isMemberFunctionPointerType()) {
if (Ovl->hasExplicitTemplateArgs()) {
// But we can still look for an explicit specialization.
if (FunctionDecl *ExplicitSpec =
S.ResolveSingleFunctionTemplateSpecialization(
Ovl, /*Complain=*/false,
/*Found=*/nullptr, FailedTSC,
/*ForTypeDeduction=*/true))
return GetTypeOfFunction(S, R, ExplicitSpec);
}
DeclAccessPair DAP;
if (FunctionDecl *Viable =
S.resolveAddressOfSingleOverloadCandidate(Arg, DAP))
return GetTypeOfFunction(S, R, Viable);
return {};
}
// Gather the explicit template arguments, if any.
TemplateArgumentListInfo ExplicitTemplateArgs;
if (Ovl->hasExplicitTemplateArgs())
Ovl->copyTemplateArgumentsInto(ExplicitTemplateArgs);
QualType Match;
for (UnresolvedSetIterator I = Ovl->decls_begin(),
E = Ovl->decls_end(); I != E; ++I) {
NamedDecl *D = (*I)->getUnderlyingDecl();
if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D)) {
// - If the argument is an overload set containing one or more
// function templates, the parameter is treated as a
// non-deduced context.
if (!Ovl->hasExplicitTemplateArgs())
return {};
// Otherwise, see if we can resolve a function type
FunctionDecl *Specialization = nullptr;
TemplateDeductionInfo Info(Ovl->getNameLoc());
if (S.DeduceTemplateArguments(FunTmpl, &ExplicitTemplateArgs,
Specialization,
Info) != TemplateDeductionResult::Success)
continue;
D = Specialization;
}
FunctionDecl *Fn = cast<FunctionDecl>(D);
QualType ArgType = GetTypeOfFunction(S, R, Fn);
if (ArgType.isNull()) continue;
// Function-to-pointer conversion.
if (!ParamWasReference && ParamType->isPointerType() &&
ArgType->isFunctionType())
ArgType = S.Context.getPointerType(ArgType);
// - If the argument is an overload set (not containing function
// templates), trial argument deduction is attempted using each
// of the members of the set. If deduction succeeds for only one
// of the overload set members, that member is used as the
// argument value for the deduction. If deduction succeeds for
// more than one member of the overload set the parameter is
// treated as a non-deduced context.
// We do all of this in a fresh context per C++0x [temp.deduct.type]p2:
// Type deduction is done independently for each P/A pair, and
// the deduced template argument values are then combined.
// So we do not reject deductions which were made elsewhere.
SmallVector<DeducedTemplateArgument, 8>
Deduced(TemplateParams->size());
TemplateDeductionInfo Info(Ovl->getNameLoc());
TemplateDeductionResult Result = DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, ParamType, ArgType, Info, Deduced, TDF,
PartialOrderingKind::None, /*DeducedFromArrayBound=*/false,
/*HasDeducedAnyParam=*/nullptr);
if (Result != TemplateDeductionResult::Success)
continue;
// C++ [temp.deduct.call]p6:
// [...] If all successful deductions yield the same deduced A, that
// deduced A is the result of deduction; otherwise, the parameter is
// treated as a non-deduced context. [...]
if (!Match.isNull() && !S.isSameOrCompatibleFunctionType(Match, ArgType))
return {};
Match = ArgType;
}
return Match;
}
/// Perform the adjustments to the parameter and argument types
/// described in C++ [temp.deduct.call].
///
/// \returns true if the caller should not attempt to perform any template
/// argument deduction based on this P/A pair because the argument is an
/// overloaded function set that could not be resolved.
static bool AdjustFunctionParmAndArgTypesForDeduction(
Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
QualType &ParamType, QualType &ArgType,
Expr::Classification ArgClassification, Expr *Arg, unsigned &TDF,
TemplateSpecCandidateSet *FailedTSC = nullptr) {
// C++0x [temp.deduct.call]p3:
// If P is a cv-qualified type, the top level cv-qualifiers of P's type
// are ignored for type deduction.
if (ParamType.hasQualifiers())
ParamType = ParamType.getUnqualifiedType();
// [...] If P is a reference type, the type referred to by P is
// used for type deduction.
const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>();
if (ParamRefType)
ParamType = ParamRefType->getPointeeType();
// Overload sets usually make this parameter an undeduced context,
// but there are sometimes special circumstances. Typically
// involving a template-id-expr.
if (ArgType == S.Context.OverloadTy) {
assert(Arg && "expected a non-null arg expression");
ArgType = ResolveOverloadForDeduction(S, TemplateParams, Arg, ParamType,
ParamRefType != nullptr, FailedTSC);
if (ArgType.isNull())
return true;
}
if (ParamRefType) {
// If the argument has incomplete array type, try to complete its type.
if (ArgType->isIncompleteArrayType()) {
assert(Arg && "expected a non-null arg expression");
ArgType = S.getCompletedType(Arg);
}
// C++1z [temp.deduct.call]p3:
// If P is a forwarding reference and the argument is an lvalue, the type
// "lvalue reference to A" is used in place of A for type deduction.
if (isForwardingReference(QualType(ParamRefType, 0), FirstInnerIndex) &&
ArgClassification.isLValue()) {
if (S.getLangOpts().OpenCL && !ArgType.hasAddressSpace())
ArgType = S.Context.getAddrSpaceQualType(
ArgType, S.Context.getDefaultOpenCLPointeeAddrSpace());
ArgType = S.Context.getLValueReferenceType(ArgType);
}
} else {
// C++ [temp.deduct.call]p2:
// If P is not a reference type:
// - If A is an array type, the pointer type produced by the
// array-to-pointer standard conversion (4.2) is used in place of
// A for type deduction; otherwise,
// - If A is a function type, the pointer type produced by the
// function-to-pointer standard conversion (4.3) is used in place
// of A for type deduction; otherwise,
if (ArgType->canDecayToPointerType())
ArgType = S.Context.getDecayedType(ArgType);
else {
// - If A is a cv-qualified type, the top level cv-qualifiers of A's
// type are ignored for type deduction.
ArgType = ArgType.getUnqualifiedType();
}
}
// C++0x [temp.deduct.call]p4:
// In general, the deduction process attempts to find template argument
// values that will make the deduced A identical to A (after the type A
// is transformed as described above). [...]
TDF = TDF_SkipNonDependent;
// - If the original P is a reference type, the deduced A (i.e., the
// type referred to by the reference) can be more cv-qualified than
// the transformed A.
if (ParamRefType)
TDF |= TDF_ParamWithReferenceType;
// - The transformed A can be another pointer or pointer to member
// type that can be converted to the deduced A via a qualification
// conversion (4.4).
if (ArgType->isPointerType() || ArgType->isMemberPointerType() ||
ArgType->isObjCObjectPointerType())
TDF |= TDF_IgnoreQualifiers;
// - If P is a class and P has the form simple-template-id, then the
// transformed A can be a derived class of the deduced A. Likewise,
// if P is a pointer to a class of the form simple-template-id, the
// transformed A can be a pointer to a derived class pointed to by
// the deduced A.
if (isSimpleTemplateIdType(ParamType) ||
(isa<PointerType>(ParamType) &&
isSimpleTemplateIdType(
ParamType->castAs<PointerType>()->getPointeeType())))
TDF |= TDF_DerivedClass;
return false;
}
static bool
hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
QualType T);
static TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
QualType ParamType, QualType ArgType,
Expr::Classification ArgClassification, Expr *Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
bool DecomposedParam, unsigned ArgIdx, unsigned TDF,
TemplateSpecCandidateSet *FailedTSC = nullptr);
/// Attempt template argument deduction from an initializer list
/// deemed to be an argument in a function call.
static TemplateDeductionResult DeduceFromInitializerList(
Sema &S, TemplateParameterList *TemplateParams, QualType AdjustedParamType,
InitListExpr *ILE, TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs, unsigned ArgIdx,
unsigned TDF) {
// C++ [temp.deduct.call]p1: (CWG 1591)
// If removing references and cv-qualifiers from P gives
// std::initializer_list<P0> or P0[N] for some P0 and N and the argument is
// a non-empty initializer list, then deduction is performed instead for
// each element of the initializer list, taking P0 as a function template
// parameter type and the initializer element as its argument
//
// We've already removed references and cv-qualifiers here.
if (!ILE->getNumInits())
return TemplateDeductionResult::Success;
QualType ElTy;
auto *ArrTy = S.Context.getAsArrayType(AdjustedParamType);
if (ArrTy)
ElTy = ArrTy->getElementType();
else if (!S.isStdInitializerList(AdjustedParamType, &ElTy)) {
// Otherwise, an initializer list argument causes the parameter to be
// considered a non-deduced context
return TemplateDeductionResult::Success;
}
// Resolving a core issue: a braced-init-list containing any designators is
// a non-deduced context.
for (Expr *E : ILE->inits())
if (isa<DesignatedInitExpr>(E))
return TemplateDeductionResult::Success;
// Deduction only needs to be done for dependent types.
if (ElTy->isDependentType()) {
for (Expr *E : ILE->inits()) {
if (auto Result = DeduceTemplateArgumentsFromCallArgument(
S, TemplateParams, 0, ElTy, E->getType(),
E->Classify(S.getASTContext()), E, Info, Deduced,
OriginalCallArgs, true, ArgIdx, TDF);
Result != TemplateDeductionResult::Success)
return Result;
}
}
// in the P0[N] case, if N is a non-type template parameter, N is deduced
// from the length of the initializer list.
if (auto *DependentArrTy = dyn_cast_or_null<DependentSizedArrayType>(ArrTy)) {
// Determine the array bound is something we can deduce.
if (const NonTypeTemplateParmDecl *NTTP =
getDeducedParameterFromExpr(Info, DependentArrTy->getSizeExpr())) {
// We can perform template argument deduction for the given non-type
// template parameter.
// C++ [temp.deduct.type]p13:
// The type of N in the type T[N] is std::size_t.
QualType T = S.Context.getSizeType();
llvm::APInt Size(S.Context.getIntWidth(T),
ILE->getNumInitsWithEmbedExpanded());
if (auto Result = DeduceNonTypeTemplateArgument(
S, TemplateParams, NTTP, llvm::APSInt(Size), T,
/*ArrayBound=*/true, Info, /*PartialOrdering=*/false, Deduced,
/*HasDeducedAnyParam=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
}
}
return TemplateDeductionResult::Success;
}
/// Perform template argument deduction per [temp.deduct.call] for a
/// single parameter / argument pair.
static TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
QualType ParamType, QualType ArgType,
Expr::Classification ArgClassification, Expr *Arg,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
bool DecomposedParam, unsigned ArgIdx, unsigned TDF,
TemplateSpecCandidateSet *FailedTSC) {
QualType OrigParamType = ParamType;
// If P is a reference type [...]
// If P is a cv-qualified type [...]
if (AdjustFunctionParmAndArgTypesForDeduction(
S, TemplateParams, FirstInnerIndex, ParamType, ArgType,
ArgClassification, Arg, TDF, FailedTSC))
return TemplateDeductionResult::Success;
// If [...] the argument is a non-empty initializer list [...]
if (InitListExpr *ILE = dyn_cast_if_present<InitListExpr>(Arg))
return DeduceFromInitializerList(S, TemplateParams, ParamType, ILE, Info,
Deduced, OriginalCallArgs, ArgIdx, TDF);
// [...] the deduction process attempts to find template argument values
// that will make the deduced A identical to A
//
// Keep track of the argument type and corresponding parameter index,
// so we can check for compatibility between the deduced A and A.
if (Arg)
OriginalCallArgs.push_back(
Sema::OriginalCallArg(OrigParamType, DecomposedParam, ArgIdx, ArgType));
return DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, ParamType, ArgType, Info, Deduced, TDF,
PartialOrderingKind::None, /*DeducedFromArrayBound=*/false,
/*HasDeducedAnyParam=*/nullptr);
}
TemplateDeductionResult Sema::DeduceTemplateArguments(
FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
bool PartialOverloading, bool AggregateDeductionCandidate,
bool PartialOrdering, QualType ObjectType,
Expr::Classification ObjectClassification,
llvm::function_ref<bool(ArrayRef<QualType>)> CheckNonDependent) {
if (FunctionTemplate->isInvalidDecl())
return TemplateDeductionResult::Invalid;
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
unsigned NumParams = Function->getNumParams();
bool HasExplicitObject = false;
int ExplicitObjectOffset = 0;
if (Function->hasCXXExplicitFunctionObjectParameter()) {
HasExplicitObject = true;
ExplicitObjectOffset = 1;
}
unsigned FirstInnerIndex = getFirstInnerIndex(FunctionTemplate);
// C++ [temp.deduct.call]p1:
// Template argument deduction is done by comparing each function template
// parameter type (call it P) with the type of the corresponding argument
// of the call (call it A) as described below.
if (Args.size() < Function->getMinRequiredExplicitArguments() &&
!PartialOverloading)
return TemplateDeductionResult::TooFewArguments;
else if (TooManyArguments(NumParams, Args.size() + ExplicitObjectOffset,
PartialOverloading)) {
const auto *Proto = Function->getType()->castAs<FunctionProtoType>();
if (Proto->isTemplateVariadic())
/* Do nothing */;
else if (!Proto->isVariadic())
return TemplateDeductionResult::TooManyArguments;
}
// The types of the parameters from which we will perform template argument
// deduction.
LocalInstantiationScope InstScope(*this);
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
SmallVector<DeducedTemplateArgument, 4> Deduced;
SmallVector<QualType, 8> ParamTypes;
unsigned NumExplicitlySpecified = 0;
if (ExplicitTemplateArgs) {
TemplateDeductionResult Result;
runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = SubstituteExplicitTemplateArguments(
FunctionTemplate, *ExplicitTemplateArgs, Deduced, ParamTypes, nullptr,
Info);
});
if (Result != TemplateDeductionResult::Success)
return Result;
NumExplicitlySpecified = Deduced.size();
} else {
// Just fill in the parameter types from the function declaration.
for (unsigned I = 0; I != NumParams; ++I)
ParamTypes.push_back(Function->getParamDecl(I)->getType());
}
SmallVector<OriginalCallArg, 8> OriginalCallArgs;
// Deduce an argument of type ParamType from an expression with index ArgIdx.
auto DeduceCallArgument = [&](QualType ParamType, unsigned ArgIdx,
bool ExplicitObjectArgument) {
// C++ [demp.deduct.call]p1: (DR1391)
// Template argument deduction is done by comparing each function template
// parameter that contains template-parameters that participate in
// template argument deduction ...
if (!hasDeducibleTemplateParameters(*this, FunctionTemplate, ParamType))
return TemplateDeductionResult::Success;
if (ExplicitObjectArgument) {
// ... with the type of the corresponding argument
return DeduceTemplateArgumentsFromCallArgument(
*this, TemplateParams, FirstInnerIndex, ParamType, ObjectType,
ObjectClassification,
/*Arg=*/nullptr, Info, Deduced, OriginalCallArgs,
/*Decomposed*/ false, ArgIdx, /*TDF*/ 0);
}
// ... with the type of the corresponding argument
return DeduceTemplateArgumentsFromCallArgument(
*this, TemplateParams, FirstInnerIndex, ParamType,
Args[ArgIdx]->getType(), Args[ArgIdx]->Classify(getASTContext()),
Args[ArgIdx], Info, Deduced, OriginalCallArgs, /*Decomposed*/ false,
ArgIdx, /*TDF*/ 0);
};
// Deduce template arguments from the function parameters.
Deduced.resize(TemplateParams->size());
SmallVector<QualType, 8> ParamTypesForArgChecking;
for (unsigned ParamIdx = 0, NumParamTypes = ParamTypes.size(), ArgIdx = 0;
ParamIdx != NumParamTypes; ++ParamIdx) {
QualType ParamType = ParamTypes[ParamIdx];
const PackExpansionType *ParamExpansion =
dyn_cast<PackExpansionType>(ParamType);
if (!ParamExpansion) {
// Simple case: matching a function parameter to a function argument.
if (ArgIdx >= Args.size() && !(HasExplicitObject && ParamIdx == 0))
break;
ParamTypesForArgChecking.push_back(ParamType);
if (ParamIdx == 0 && HasExplicitObject) {
if (ObjectType.isNull())
return TemplateDeductionResult::InvalidExplicitArguments;
if (auto Result = DeduceCallArgument(ParamType, 0,
/*ExplicitObjectArgument=*/true);
Result != TemplateDeductionResult::Success)
return Result;
continue;
}
if (auto Result = DeduceCallArgument(ParamType, ArgIdx++,
/*ExplicitObjectArgument=*/false);
Result != TemplateDeductionResult::Success)
return Result;
continue;
}
bool IsTrailingPack = ParamIdx + 1 == NumParamTypes;
QualType ParamPattern = ParamExpansion->getPattern();
PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
ParamPattern,
AggregateDeductionCandidate && IsTrailingPack);
// C++0x [temp.deduct.call]p1:
// For a function parameter pack that occurs at the end of the
// parameter-declaration-list, the type A of each remaining argument of
// the call is compared with the type P of the declarator-id of the
// function parameter pack. Each comparison deduces template arguments
// for subsequent positions in the template parameter packs expanded by
// the function parameter pack. When a function parameter pack appears
// in a non-deduced context [not at the end of the list], the type of
// that parameter pack is never deduced.
//
// FIXME: The above rule allows the size of the parameter pack to change
// after we skip it (in the non-deduced case). That makes no sense, so
// we instead notionally deduce the pack against N arguments, where N is
// the length of the explicitly-specified pack if it's expanded by the
// parameter pack and 0 otherwise, and we treat each deduction as a
// non-deduced context.
if (IsTrailingPack || PackScope.hasFixedArity()) {
for (; ArgIdx < Args.size() && PackScope.hasNextElement();
PackScope.nextPackElement(), ++ArgIdx) {
ParamTypesForArgChecking.push_back(ParamPattern);
if (auto Result = DeduceCallArgument(ParamPattern, ArgIdx,
/*ExplicitObjectArgument=*/false);
Result != TemplateDeductionResult::Success)
return Result;
}
} else {
// If the parameter type contains an explicitly-specified pack that we
// could not expand, skip the number of parameters notionally created
// by the expansion.
std::optional<unsigned> NumExpansions =
ParamExpansion->getNumExpansions();
if (NumExpansions && !PackScope.isPartiallyExpanded()) {
for (unsigned I = 0; I != *NumExpansions && ArgIdx < Args.size();
++I, ++ArgIdx) {
ParamTypesForArgChecking.push_back(ParamPattern);
// FIXME: Should we add OriginalCallArgs for these? What if the
// corresponding argument is a list?
PackScope.nextPackElement();
}
} else if (!IsTrailingPack && !PackScope.isPartiallyExpanded() &&
PackScope.isDeducedFromEarlierParameter()) {
// [temp.deduct.general#3]
// When all template arguments have been deduced
// or obtained from default template arguments, all uses of template
// parameters in the template parameter list of the template are
// replaced with the corresponding deduced or default argument values
//
// If we have a trailing parameter pack, that has been deduced
// previously we substitute the pack here in a similar fashion as
// above with the trailing parameter packs. The main difference here is
// that, in this case we are not processing all of the remaining
// arguments. We are only process as many arguments as we have in
// the already deduced parameter.
std::optional<unsigned> ArgPosAfterSubstitution =
PackScope.getSavedPackSizeIfAllEqual();
if (!ArgPosAfterSubstitution)
continue;
unsigned PackArgEnd = ArgIdx + *ArgPosAfterSubstitution;
for (; ArgIdx < PackArgEnd && ArgIdx < Args.size(); ArgIdx++) {
ParamTypesForArgChecking.push_back(ParamPattern);
if (auto Result =
DeduceCallArgument(ParamPattern, ArgIdx,
/*ExplicitObjectArgument=*/false);
Result != TemplateDeductionResult::Success)
return Result;
PackScope.nextPackElement();
}
}
}
// Build argument packs for each of the parameter packs expanded by this
// pack expansion.
if (auto Result = PackScope.finish();
Result != TemplateDeductionResult::Success)
return Result;
}
// Capture the context in which the function call is made. This is the context
// that is needed when the accessibility of template arguments is checked.
DeclContext *CallingCtx = CurContext;
TemplateDeductionResult Result;
runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = FinishTemplateArgumentDeduction(
FunctionTemplate, Deduced, NumExplicitlySpecified, Specialization, Info,
&OriginalCallArgs, PartialOverloading, PartialOrdering,
[&, CallingCtx]() {
ContextRAII SavedContext(*this, CallingCtx);
return CheckNonDependent(ParamTypesForArgChecking);
});
});
return Result;
}
QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
QualType FunctionType,
bool AdjustExceptionSpec) {
if (ArgFunctionType.isNull())
return ArgFunctionType;
const auto *FunctionTypeP = FunctionType->castAs<FunctionProtoType>();
const auto *ArgFunctionTypeP = ArgFunctionType->castAs<FunctionProtoType>();
FunctionProtoType::ExtProtoInfo EPI = ArgFunctionTypeP->getExtProtoInfo();
bool Rebuild = false;
CallingConv CC = FunctionTypeP->getCallConv();
if (EPI.ExtInfo.getCC() != CC) {
EPI.ExtInfo = EPI.ExtInfo.withCallingConv(CC);
Rebuild = true;
}
bool NoReturn = FunctionTypeP->getNoReturnAttr();
if (EPI.ExtInfo.getNoReturn() != NoReturn) {
EPI.ExtInfo = EPI.ExtInfo.withNoReturn(NoReturn);
Rebuild = true;
}
if (AdjustExceptionSpec && (FunctionTypeP->hasExceptionSpec() ||
ArgFunctionTypeP->hasExceptionSpec())) {
EPI.ExceptionSpec = FunctionTypeP->getExtProtoInfo().ExceptionSpec;
Rebuild = true;
}
if (!Rebuild)
return ArgFunctionType;
return Context.getFunctionType(ArgFunctionTypeP->getReturnType(),
ArgFunctionTypeP->getParamTypes(), EPI);
}
TemplateDeductionResult Sema::DeduceTemplateArguments(
FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo *ExplicitTemplateArgs, QualType ArgFunctionType,
FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
bool IsAddressOfFunction) {
if (FunctionTemplate->isInvalidDecl())
return TemplateDeductionResult::Invalid;
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
QualType FunctionType = Function->getType();
// Substitute any explicit template arguments.
LocalInstantiationScope InstScope(*this);
SmallVector<DeducedTemplateArgument, 4> Deduced;
unsigned NumExplicitlySpecified = 0;
SmallVector<QualType, 4> ParamTypes;
if (ExplicitTemplateArgs) {
TemplateDeductionResult Result;
runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = SubstituteExplicitTemplateArguments(
FunctionTemplate, *ExplicitTemplateArgs, Deduced, ParamTypes,
&FunctionType, Info);
});
if (Result != TemplateDeductionResult::Success)
return Result;
NumExplicitlySpecified = Deduced.size();
}
// When taking the address of a function, we require convertibility of
// the resulting function type. Otherwise, we allow arbitrary mismatches
// of calling convention and noreturn.
if (!IsAddressOfFunction)
ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
/*AdjustExceptionSpec*/false);
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
*this, Sema::ExpressionEvaluationContext::Unevaluated);
SFINAETrap Trap(*this);
Deduced.resize(TemplateParams->size());
// If the function has a deduced return type, substitute it for a dependent
// type so that we treat it as a non-deduced context in what follows.
bool HasDeducedReturnType = false;
if (getLangOpts().CPlusPlus14 &&
Function->getReturnType()->getContainedAutoType()) {
FunctionType = SubstAutoTypeDependent(FunctionType);
HasDeducedReturnType = true;
}
if (!ArgFunctionType.isNull() && !FunctionType.isNull()) {
unsigned TDF =
TDF_TopLevelParameterTypeList | TDF_AllowCompatibleFunctionType;
// Deduce template arguments from the function type.
if (TemplateDeductionResult Result = DeduceTemplateArgumentsByTypeMatch(
*this, TemplateParams, FunctionType, ArgFunctionType, Info, Deduced,
TDF, PartialOrderingKind::None, /*DeducedFromArrayBound=*/false,
/*HasDeducedAnyParam=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
}
TemplateDeductionResult Result;
runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = FinishTemplateArgumentDeduction(
FunctionTemplate, Deduced, NumExplicitlySpecified, Specialization, Info,
/*OriginalCallArgs=*/nullptr, /*PartialOverloading=*/false,
/*PartialOrdering=*/true);
});
if (Result != TemplateDeductionResult::Success)
return Result;
// If the function has a deduced return type, deduce it now, so we can check
// that the deduced function type matches the requested type.
if (HasDeducedReturnType && IsAddressOfFunction &&
Specialization->getReturnType()->isUndeducedType() &&
DeduceReturnType(Specialization, Info.getLocation(), false))
return TemplateDeductionResult::MiscellaneousDeductionFailure;
// [C++26][expr.const]/p17
// An expression or conversion is immediate-escalating if it is not initially
// in an immediate function context and it is [...]
// a potentially-evaluated id-expression that denotes an immediate function.
if (IsAddressOfFunction && getLangOpts().CPlusPlus20 &&
Specialization->isImmediateEscalating() &&
parentEvaluationContext().isPotentiallyEvaluated() &&
CheckIfFunctionSpecializationIsImmediate(Specialization,
Info.getLocation()))
return TemplateDeductionResult::MiscellaneousDeductionFailure;
// Adjust the exception specification of the argument to match the
// substituted and resolved type we just formed. (Calling convention and
// noreturn can't be dependent, so we don't actually need this for them
// right now.)
QualType SpecializationType = Specialization->getType();
if (!IsAddressOfFunction) {
ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, SpecializationType,
/*AdjustExceptionSpec*/true);
// Revert placeholder types in the return type back to undeduced types so
// that the comparison below compares the declared return types.
if (HasDeducedReturnType) {
SpecializationType = SubstAutoType(SpecializationType, QualType());
ArgFunctionType = SubstAutoType(ArgFunctionType, QualType());
}
}
// If the requested function type does not match the actual type of the
// specialization with respect to arguments of compatible pointer to function
// types, template argument deduction fails.
if (!ArgFunctionType.isNull()) {
if (IsAddressOfFunction ? !isSameOrCompatibleFunctionType(
SpecializationType, ArgFunctionType)
: !Context.hasSameFunctionTypeIgnoringExceptionSpec(
SpecializationType, ArgFunctionType)) {
Info.FirstArg = TemplateArgument(SpecializationType);
Info.SecondArg = TemplateArgument(ArgFunctionType);
return TemplateDeductionResult::NonDeducedMismatch;
}
}
return TemplateDeductionResult::Success;
}
TemplateDeductionResult Sema::DeduceTemplateArguments(
FunctionTemplateDecl *ConversionTemplate, QualType ObjectType,
Expr::Classification ObjectClassification, QualType A,
CXXConversionDecl *&Specialization, TemplateDeductionInfo &Info) {
if (ConversionTemplate->isInvalidDecl())
return TemplateDeductionResult::Invalid;
CXXConversionDecl *ConversionGeneric
= cast<CXXConversionDecl>(ConversionTemplate->getTemplatedDecl());
QualType P = ConversionGeneric->getConversionType();
bool IsReferenceP = P->isReferenceType();
bool IsReferenceA = A->isReferenceType();
// C++0x [temp.deduct.conv]p2:
// If P is a reference type, the type referred to by P is used for
// type deduction.
if (const ReferenceType *PRef = P->getAs<ReferenceType>())
P = PRef->getPointeeType();
// C++0x [temp.deduct.conv]p4:
// [...] If A is a reference type, the type referred to by A is used
// for type deduction.
if (const ReferenceType *ARef = A->getAs<ReferenceType>()) {
A = ARef->getPointeeType();
// We work around a defect in the standard here: cv-qualifiers are also
// removed from P and A in this case, unless P was a reference type. This
// seems to mostly match what other compilers are doing.
if (!IsReferenceP) {
A = A.getUnqualifiedType();
P = P.getUnqualifiedType();
}
// C++ [temp.deduct.conv]p3:
//
// If A is not a reference type:
} else {
assert(!A->isReferenceType() && "Reference types were handled above");
// - If P is an array type, the pointer type produced by the
// array-to-pointer standard conversion (4.2) is used in place
// of P for type deduction; otherwise,
if (P->isArrayType())
P = Context.getArrayDecayedType(P);
// - If P is a function type, the pointer type produced by the
// function-to-pointer standard conversion (4.3) is used in
// place of P for type deduction; otherwise,
else if (P->isFunctionType())
P = Context.getPointerType(P);
// - If P is a cv-qualified type, the top level cv-qualifiers of
// P's type are ignored for type deduction.
else
P = P.getUnqualifiedType();
// C++0x [temp.deduct.conv]p4:
// If A is a cv-qualified type, the top level cv-qualifiers of A's
// type are ignored for type deduction. If A is a reference type, the type
// referred to by A is used for type deduction.
A = A.getUnqualifiedType();
}
// Unevaluated SFINAE context.
EnterExpressionEvaluationContext Unevaluated(
*this, Sema::ExpressionEvaluationContext::Unevaluated);
SFINAETrap Trap(*this);
// C++ [temp.deduct.conv]p1:
// Template argument deduction is done by comparing the return
// type of the template conversion function (call it P) with the
// type that is required as the result of the conversion (call it
// A) as described in 14.8.2.4.
TemplateParameterList *TemplateParams
= ConversionTemplate->getTemplateParameters();
SmallVector<DeducedTemplateArgument, 4> Deduced;
Deduced.resize(TemplateParams->size());
// C++0x [temp.deduct.conv]p4:
// In general, the deduction process attempts to find template
// argument values that will make the deduced A identical to
// A. However, there are two cases that allow a difference:
unsigned TDF = 0;
// - If the original A is a reference type, A can be more
// cv-qualified than the deduced A (i.e., the type referred to
// by the reference)
if (IsReferenceA)
TDF |= TDF_ArgWithReferenceType;
// - The deduced A can be another pointer or pointer to member
// type that can be converted to A via a qualification
// conversion.
//
// (C++0x [temp.deduct.conv]p6 clarifies that this only happens when
// both P and A are pointers or member pointers. In this case, we
// just ignore cv-qualifiers completely).
if ((P->isPointerType() && A->isPointerType()) ||
(P->isMemberPointerType() && A->isMemberPointerType()))
TDF |= TDF_IgnoreQualifiers;
SmallVector<Sema::OriginalCallArg, 1> OriginalCallArgs;
if (ConversionGeneric->isExplicitObjectMemberFunction()) {
QualType ParamType = ConversionGeneric->getParamDecl(0)->getType();
if (TemplateDeductionResult Result =
DeduceTemplateArgumentsFromCallArgument(
*this, TemplateParams, getFirstInnerIndex(ConversionTemplate),
ParamType, ObjectType, ObjectClassification,
/*Arg=*/nullptr, Info, Deduced, OriginalCallArgs,
/*Decomposed*/ false, 0, /*TDF*/ 0);
Result != TemplateDeductionResult::Success)
return Result;
}
if (TemplateDeductionResult Result = DeduceTemplateArgumentsByTypeMatch(
*this, TemplateParams, P, A, Info, Deduced, TDF,
PartialOrderingKind::None, /*DeducedFromArrayBound=*/false,
/*HasDeducedAnyParam=*/nullptr);
Result != TemplateDeductionResult::Success)
return Result;
// Create an Instantiation Scope for finalizing the operator.
LocalInstantiationScope InstScope(*this);
// Finish template argument deduction.
FunctionDecl *ConversionSpecialized = nullptr;
TemplateDeductionResult Result;
runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = FinishTemplateArgumentDeduction(
ConversionTemplate, Deduced, 0, ConversionSpecialized, Info,
&OriginalCallArgs, /*PartialOverloading=*/false,
/*PartialOrdering=*/false);
});
Specialization = cast_or_null<CXXConversionDecl>(ConversionSpecialized);
return Result;
}
TemplateDeductionResult
Sema::DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
TemplateArgumentListInfo *ExplicitTemplateArgs,
FunctionDecl *&Specialization,
TemplateDeductionInfo &Info,
bool IsAddressOfFunction) {
return DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs,
QualType(), Specialization, Info,
IsAddressOfFunction);
}
namespace {
struct DependentAuto { bool IsPack; };
/// Substitute the 'auto' specifier or deduced template specialization type
/// specifier within a type for a given replacement type.
class SubstituteDeducedTypeTransform :
public TreeTransform<SubstituteDeducedTypeTransform> {
QualType Replacement;
bool ReplacementIsPack;
bool UseTypeSugar;
using inherited = TreeTransform<SubstituteDeducedTypeTransform>;
public:
SubstituteDeducedTypeTransform(Sema &SemaRef, DependentAuto DA)
: TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
ReplacementIsPack(DA.IsPack), UseTypeSugar(true) {}
SubstituteDeducedTypeTransform(Sema &SemaRef, QualType Replacement,
bool UseTypeSugar = true)
: TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
Replacement(Replacement), ReplacementIsPack(false),
UseTypeSugar(UseTypeSugar) {}
QualType TransformDesugared(TypeLocBuilder &TLB, DeducedTypeLoc TL) {
assert(isa<TemplateTypeParmType>(Replacement) &&
"unexpected unsugared replacement kind");
QualType Result = Replacement;
TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
NewTL.setNameLoc(TL.getNameLoc());
return Result;
}
QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
// If we're building the type pattern to deduce against, don't wrap the
// substituted type in an AutoType. Certain template deduction rules
// apply only when a template type parameter appears directly (and not if
// the parameter is found through desugaring). For instance:
// auto &&lref = lvalue;
// must transform into "rvalue reference to T" not "rvalue reference to
// auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
//
// FIXME: Is this still necessary?
if (!UseTypeSugar)
return TransformDesugared(TLB, TL);
QualType Result = SemaRef.Context.getAutoType(
Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull(),
ReplacementIsPack, TL.getTypePtr()->getTypeConstraintConcept(),
TL.getTypePtr()->getTypeConstraintArguments());
auto NewTL = TLB.push<AutoTypeLoc>(Result);
NewTL.copy(TL);
return Result;
}
QualType TransformDeducedTemplateSpecializationType(
TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
if (!UseTypeSugar)
return TransformDesugared(TLB, TL);
QualType Result = SemaRef.Context.getDeducedTemplateSpecializationType(
TL.getTypePtr()->getTemplateName(),
Replacement, Replacement.isNull());
auto NewTL = TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
NewTL.setNameLoc(TL.getNameLoc());
return Result;
}
ExprResult TransformLambdaExpr(LambdaExpr *E) {
// Lambdas never need to be transformed.
return E;
}
bool TransformExceptionSpec(SourceLocation Loc,
FunctionProtoType::ExceptionSpecInfo &ESI,
SmallVectorImpl<QualType> &Exceptions,
bool &Changed) {
if (ESI.Type == EST_Uninstantiated) {
ESI.instantiate();
Changed = true;
}
return inherited::TransformExceptionSpec(Loc, ESI, Exceptions, Changed);
}
QualType Apply(TypeLoc TL) {
// Create some scratch storage for the transformed type locations.
// FIXME: We're just going to throw this information away. Don't build it.
TypeLocBuilder TLB;
TLB.reserve(TL.getFullDataSize());
return TransformType(TLB, TL);
}
};
} // namespace
static bool CheckDeducedPlaceholderConstraints(Sema &S, const AutoType &Type,
AutoTypeLoc TypeLoc,
QualType Deduced) {
ConstraintSatisfaction Satisfaction;
ConceptDecl *Concept = Type.getTypeConstraintConcept();
TemplateArgumentListInfo TemplateArgs(TypeLoc.getLAngleLoc(),
TypeLoc.getRAngleLoc());
TemplateArgs.addArgument(
TemplateArgumentLoc(TemplateArgument(Deduced),
S.Context.getTrivialTypeSourceInfo(
Deduced, TypeLoc.getNameLoc())));
for (unsigned I = 0, C = TypeLoc.getNumArgs(); I != C; ++I)
TemplateArgs.addArgument(TypeLoc.getArgLoc(I));
Sema::CheckTemplateArgumentInfo CTAI;
if (S.CheckTemplateArgumentList(Concept, SourceLocation(), TemplateArgs,
/*DefaultArgs=*/{},
/*PartialTemplateArgs=*/false, CTAI))
return true;
MultiLevelTemplateArgumentList MLTAL(Concept, CTAI.CanonicalConverted,
/*Final=*/false);
// Build up an EvaluationContext with an ImplicitConceptSpecializationDecl so
// that the template arguments of the constraint can be preserved. For
// example:
//
// template <class T>
// concept C = []<D U = void>() { return true; }();
//
// We need the argument for T while evaluating type constraint D in
// building the CallExpr to the lambda.
EnterExpressionEvaluationContext EECtx(
S, Sema::ExpressionEvaluationContext::Unevaluated,
ImplicitConceptSpecializationDecl::Create(
S.getASTContext(), Concept->getDeclContext(), Concept->getLocation(),
CTAI.CanonicalConverted));
if (S.CheckConstraintSatisfaction(Concept, {Concept->getConstraintExpr()},
MLTAL, TypeLoc.getLocalSourceRange(),
Satisfaction))
return true;
if (!Satisfaction.IsSatisfied) {
std::string Buf;
llvm::raw_string_ostream OS(Buf);
OS << "'" << Concept->getName();
if (TypeLoc.hasExplicitTemplateArgs()) {
printTemplateArgumentList(
OS, Type.getTypeConstraintArguments(), S.getPrintingPolicy(),
Type.getTypeConstraintConcept()->getTemplateParameters());
}
OS << "'";
S.Diag(TypeLoc.getConceptNameLoc(),
diag::err_placeholder_constraints_not_satisfied)
<< Deduced << Buf << TypeLoc.getLocalSourceRange();
S.DiagnoseUnsatisfiedConstraint(Satisfaction);
return true;
}
return false;
}
TemplateDeductionResult
Sema::DeduceAutoType(TypeLoc Type, Expr *Init, QualType &Result,
TemplateDeductionInfo &Info, bool DependentDeduction,
bool IgnoreConstraints,
TemplateSpecCandidateSet *FailedTSC) {
assert(DependentDeduction || Info.getDeducedDepth() == 0);
if (Init->containsErrors())
return TemplateDeductionResult::AlreadyDiagnosed;
const AutoType *AT = Type.getType()->getContainedAutoType();
assert(AT);
if (Init->getType()->isNonOverloadPlaceholderType() || AT->isDecltypeAuto()) {
ExprResult NonPlaceholder = CheckPlaceholderExpr(Init);
if (NonPlaceholder.isInvalid())
return TemplateDeductionResult::AlreadyDiagnosed;
Init = NonPlaceholder.get();
}
DependentAuto DependentResult = {
/*.IsPack = */ (bool)Type.getAs<PackExpansionTypeLoc>()};
if (!DependentDeduction &&
(Type.getType()->isDependentType() || Init->isTypeDependent() ||
Init->containsUnexpandedParameterPack())) {
Result = SubstituteDeducedTypeTransform(*this, DependentResult).Apply(Type);
assert(!Result.isNull() && "substituting DependentTy can't fail");
return TemplateDeductionResult::Success;
}
// Make sure that we treat 'char[]' equaly as 'char*' in C23 mode.
auto *String = dyn_cast<StringLiteral>(Init);
if (getLangOpts().C23 && String && Type.getType()->isArrayType()) {
Diag(Type.getBeginLoc(), diag::ext_c23_auto_non_plain_identifier);
TypeLoc TL = TypeLoc(Init->getType(), Type.getOpaqueData());
Result = SubstituteDeducedTypeTransform(*this, DependentResult).Apply(TL);
assert(!Result.isNull() && "substituting DependentTy can't fail");
return TemplateDeductionResult::Success;
}
// Emit a warning if 'auto*' is used in pedantic and in C23 mode.
if (getLangOpts().C23 && Type.getType()->isPointerType()) {
Diag(Type.getBeginLoc(), diag::ext_c23_auto_non_plain_identifier);
}
auto *InitList = dyn_cast<InitListExpr>(Init);
if (!getLangOpts().CPlusPlus && InitList) {
Diag(Init->getBeginLoc(), diag::err_auto_init_list_from_c)
<< (int)AT->getKeyword() << getLangOpts().C23;
return TemplateDeductionResult::AlreadyDiagnosed;
}
// Deduce type of TemplParam in Func(Init)
SmallVector<DeducedTemplateArgument, 1> Deduced;
Deduced.resize(1);
// If deduction failed, don't diagnose if the initializer is dependent; it
// might acquire a matching type in the instantiation.
auto DeductionFailed = [&](TemplateDeductionResult TDK) {
if (Init->isTypeDependent()) {
Result =
SubstituteDeducedTypeTransform(*this, DependentResult).Apply(Type);
assert(!Result.isNull() && "substituting DependentTy can't fail");
return TemplateDeductionResult::Success;
}
return TDK;
};
SmallVector<OriginalCallArg, 4> OriginalCallArgs;
QualType DeducedType;
// If this is a 'decltype(auto)' specifier, do the decltype dance.
if (AT->isDecltypeAuto()) {
if (InitList) {
Diag(Init->getBeginLoc(), diag::err_decltype_auto_initializer_list);
return TemplateDeductionResult::AlreadyDiagnosed;
}
DeducedType = getDecltypeForExpr(Init);
assert(!DeducedType.isNull());
} else {
LocalInstantiationScope InstScope(*this);
// Build template<class TemplParam> void Func(FuncParam);
SourceLocation Loc = Init->getExprLoc();
TemplateTypeParmDecl *TemplParam = TemplateTypeParmDecl::Create(
Context, nullptr, SourceLocation(), Loc, Info.getDeducedDepth(), 0,
nullptr, false, false, false);
QualType TemplArg = QualType(TemplParam->getTypeForDecl(), 0);
NamedDecl *TemplParamPtr = TemplParam;
FixedSizeTemplateParameterListStorage<1, false> TemplateParamsSt(
Context, Loc, Loc, TemplParamPtr, Loc, nullptr);
if (InitList) {
// Notionally, we substitute std::initializer_list<T> for 'auto' and
// deduce against that. Such deduction only succeeds if removing
// cv-qualifiers and references results in std::initializer_list<T>.
if (!Type.getType().getNonReferenceType()->getAs<AutoType>())
return TemplateDeductionResult::Invalid;
SourceRange DeducedFromInitRange;
for (Expr *Init : InitList->inits()) {
// Resolving a core issue: a braced-init-list containing any designators
// is a non-deduced context.
if (isa<DesignatedInitExpr>(Init))
return TemplateDeductionResult::Invalid;
if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
*this, TemplateParamsSt.get(), 0, TemplArg, Init->getType(),
Init->Classify(getASTContext()), Init, Info, Deduced,
OriginalCallArgs,
/*Decomposed=*/true,
/*ArgIdx=*/0, /*TDF=*/0);
TDK != TemplateDeductionResult::Success) {
if (TDK == TemplateDeductionResult::Inconsistent) {
Diag(Info.getLocation(), diag::err_auto_inconsistent_deduction)
<< Info.FirstArg << Info.SecondArg << DeducedFromInitRange
<< Init->getSourceRange();
return DeductionFailed(TemplateDeductionResult::AlreadyDiagnosed);
}
return DeductionFailed(TDK);
}
if (DeducedFromInitRange.isInvalid() &&
Deduced[0].getKind() != TemplateArgument::Null)
DeducedFromInitRange = Init->getSourceRange();
}
} else {
if (!getLangOpts().CPlusPlus && Init->refersToBitField()) {
Diag(Loc, diag::err_auto_bitfield);
return TemplateDeductionResult::AlreadyDiagnosed;
}
QualType FuncParam =
SubstituteDeducedTypeTransform(*this, TemplArg).Apply(Type);
assert(!FuncParam.isNull() &&
"substituting template parameter for 'auto' failed");
if (auto TDK = DeduceTemplateArgumentsFromCallArgument(
*this, TemplateParamsSt.get(), 0, FuncParam, Init->getType(),
Init->Classify(getASTContext()), Init, Info, Deduced,
OriginalCallArgs,
/*Decomposed=*/false, /*ArgIdx=*/0, /*TDF=*/0, FailedTSC);
TDK != TemplateDeductionResult::Success)
return DeductionFailed(TDK);
}
// Could be null if somehow 'auto' appears in a non-deduced context.
if (Deduced[0].getKind() != TemplateArgument::Type)
return DeductionFailed(TemplateDeductionResult::Incomplete);
DeducedType = Deduced[0].getAsType();
if (InitList) {
DeducedType = BuildStdInitializerList(DeducedType, Loc);
if (DeducedType.isNull())
return TemplateDeductionResult::AlreadyDiagnosed;
}
}
if (!Result.isNull()) {
if (!Context.hasSameType(DeducedType, Result)) {
Info.FirstArg = Result;
Info.SecondArg = DeducedType;
return DeductionFailed(TemplateDeductionResult::Inconsistent);
}
DeducedType = Context.getCommonSugaredType(Result, DeducedType);
}
if (AT->isConstrained() && !IgnoreConstraints &&
CheckDeducedPlaceholderConstraints(
*this, *AT, Type.getContainedAutoTypeLoc(), DeducedType))
return TemplateDeductionResult::AlreadyDiagnosed;
Result = SubstituteDeducedTypeTransform(*this, DeducedType).Apply(Type);
if (Result.isNull())
return TemplateDeductionResult::AlreadyDiagnosed;
// Check that the deduced argument type is compatible with the original
// argument type per C++ [temp.deduct.call]p4.
QualType DeducedA = InitList ? Deduced[0].getAsType() : Result;
for (const OriginalCallArg &OriginalArg : OriginalCallArgs) {
assert((bool)InitList == OriginalArg.DecomposedParam &&
"decomposed non-init-list in auto deduction?");
if (auto TDK =
CheckOriginalCallArgDeduction(*this, Info, OriginalArg, DeducedA);
TDK != TemplateDeductionResult::Success) {
Result = QualType();
return DeductionFailed(TDK);
}
}
return TemplateDeductionResult::Success;
}
QualType Sema::SubstAutoType(QualType TypeWithAuto,
QualType TypeToReplaceAuto) {
assert(TypeToReplaceAuto != Context.DependentTy);
return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
.TransformType(TypeWithAuto);
}
TypeSourceInfo *Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
QualType TypeToReplaceAuto) {
assert(TypeToReplaceAuto != Context.DependentTy);
return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
.TransformType(TypeWithAuto);
}
QualType Sema::SubstAutoTypeDependent(QualType TypeWithAuto) {
return SubstituteDeducedTypeTransform(*this, DependentAuto{false})
.TransformType(TypeWithAuto);
}
TypeSourceInfo *
Sema::SubstAutoTypeSourceInfoDependent(TypeSourceInfo *TypeWithAuto) {
return SubstituteDeducedTypeTransform(*this, DependentAuto{false})
.TransformType(TypeWithAuto);
}
QualType Sema::ReplaceAutoType(QualType TypeWithAuto,
QualType TypeToReplaceAuto) {
return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
/*UseTypeSugar*/ false)
.TransformType(TypeWithAuto);
}
TypeSourceInfo *Sema::ReplaceAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
QualType TypeToReplaceAuto) {
return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
/*UseTypeSugar*/ false)
.TransformType(TypeWithAuto);
}
void Sema::DiagnoseAutoDeductionFailure(const VarDecl *VDecl,
const Expr *Init) {
if (isa<InitListExpr>(Init))
Diag(VDecl->getLocation(),
VDecl->isInitCapture()
? diag::err_init_capture_deduction_failure_from_init_list
: diag::err_auto_var_deduction_failure_from_init_list)
<< VDecl->getDeclName() << VDecl->getType() << Init->getSourceRange();
else
Diag(VDecl->getLocation(),
VDecl->isInitCapture() ? diag::err_init_capture_deduction_failure
: diag::err_auto_var_deduction_failure)
<< VDecl->getDeclName() << VDecl->getType() << Init->getType()
<< Init->getSourceRange();
}
bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
bool Diagnose) {
assert(FD->getReturnType()->isUndeducedType());
// For a lambda's conversion operator, deduce any 'auto' or 'decltype(auto)'
// within the return type from the call operator's type.
if (isLambdaConversionOperator(FD)) {
CXXRecordDecl *Lambda = cast<CXXMethodDecl>(FD)->getParent();
FunctionDecl *CallOp = Lambda->getLambdaCallOperator();
// For a generic lambda, instantiate the call operator if needed.
if (auto *Args = FD->getTemplateSpecializationArgs()) {
CallOp = InstantiateFunctionDeclaration(
CallOp->getDescribedFunctionTemplate(), Args, Loc);
if (!CallOp || CallOp->isInvalidDecl())
return true;
// We might need to deduce the return type by instantiating the definition
// of the operator() function.
if (CallOp->getReturnType()->isUndeducedType()) {
runWithSufficientStackSpace(Loc, [&] {
InstantiateFunctionDefinition(Loc, CallOp);
});
}
}
if (CallOp->isInvalidDecl())
return true;
assert(!CallOp->getReturnType()->isUndeducedType() &&
"failed to deduce lambda return type");
// Build the new return type from scratch.
CallingConv RetTyCC = FD->getReturnType()
->getPointeeType()
->castAs<FunctionType>()
->getCallConv();
QualType RetType = getLambdaConversionFunctionResultType(
CallOp->getType()->castAs<FunctionProtoType>(), RetTyCC);
if (FD->getReturnType()->getAs<PointerType>())
RetType = Context.getPointerType(RetType);
else {
assert(FD->getReturnType()->getAs<BlockPointerType>());
RetType = Context.getBlockPointerType(RetType);
}
Context.adjustDeducedFunctionResultType(FD, RetType);
return false;
}
if (FD->getTemplateInstantiationPattern()) {
runWithSufficientStackSpace(Loc, [&] {
InstantiateFunctionDefinition(Loc, FD);
});
}
bool StillUndeduced = FD->getReturnType()->isUndeducedType();
if (StillUndeduced && Diagnose && !FD->isInvalidDecl()) {
Diag(Loc, diag::err_auto_fn_used_before_defined) << FD;
Diag(FD->getLocation(), diag::note_callee_decl) << FD;
}
return StillUndeduced;
}
bool Sema::CheckIfFunctionSpecializationIsImmediate(FunctionDecl *FD,
SourceLocation Loc) {
assert(FD->isImmediateEscalating());
if (isLambdaConversionOperator(FD)) {
CXXRecordDecl *Lambda = cast<CXXMethodDecl>(FD)->getParent();
FunctionDecl *CallOp = Lambda->getLambdaCallOperator();
// For a generic lambda, instantiate the call operator if needed.
if (auto *Args = FD->getTemplateSpecializationArgs()) {
CallOp = InstantiateFunctionDeclaration(
CallOp->getDescribedFunctionTemplate(), Args, Loc);
if (!CallOp || CallOp->isInvalidDecl())
return true;
runWithSufficientStackSpace(
Loc, [&] { InstantiateFunctionDefinition(Loc, CallOp); });
}
return CallOp->isInvalidDecl();
}
if (FD->getTemplateInstantiationPattern()) {
runWithSufficientStackSpace(
Loc, [&] { InstantiateFunctionDefinition(Loc, FD); });
}
return false;
}
static QualType GetImplicitObjectParameterType(ASTContext &Context,
const CXXMethodDecl *Method,
QualType RawType,
bool IsOtherRvr) {
// C++20 [temp.func.order]p3.1, p3.2:
// - The type X(M) is "rvalue reference to cv A" if the optional
// ref-qualifier of M is && or if M has no ref-qualifier and the
// positionally-corresponding parameter of the other transformed template
// has rvalue reference type; if this determination depends recursively
// upon whether X(M) is an rvalue reference type, it is not considered to
// have rvalue reference type.
//
// - Otherwise, X(M) is "lvalue reference to cv A".
assert(Method && !Method->isExplicitObjectMemberFunction() &&
"expected a member function with no explicit object parameter");
RawType = Context.getQualifiedType(RawType, Method->getMethodQualifiers());
if (Method->getRefQualifier() == RQ_RValue ||
(IsOtherRvr && Method->getRefQualifier() == RQ_None))
return Context.getRValueReferenceType(RawType);
return Context.getLValueReferenceType(RawType);
}
static TemplateDeductionResult CheckDeductionConsistency(
Sema &S, FunctionTemplateDecl *FTD, int ArgIdx, QualType P, QualType A,
ArrayRef<TemplateArgument> DeducedArgs, bool CheckConsistency) {
MultiLevelTemplateArgumentList MLTAL(FTD, DeducedArgs,
/*Final=*/true);
Sema::ArgumentPackSubstitutionIndexRAII PackIndex(
S, ArgIdx != -1 ? ::getPackIndexForParam(S, FTD, MLTAL, ArgIdx) : -1);
bool IsIncompleteSubstitution = false;
// FIXME: A substitution can be incomplete on a non-structural part of the
// type. Use the canonical type for now, until the TemplateInstantiator can
// deal with that.
QualType InstP = S.SubstType(P.getCanonicalType(), MLTAL, FTD->getLocation(),
FTD->getDeclName(), &IsIncompleteSubstitution);
if (InstP.isNull() && !IsIncompleteSubstitution)
return TemplateDeductionResult::SubstitutionFailure;
if (!CheckConsistency)
return TemplateDeductionResult::Success;
if (IsIncompleteSubstitution)
return TemplateDeductionResult::Incomplete;
// [temp.deduct.call]/4 - Check we produced a consistent deduction.
// This handles just the cases that can appear when partial ordering.
if (auto *PA = dyn_cast<PackExpansionType>(A);
PA && !isa<PackExpansionType>(InstP))
A = PA->getPattern();
if (!S.Context.hasSameType(
S.Context.getUnqualifiedArrayType(InstP.getNonReferenceType()),
S.Context.getUnqualifiedArrayType(A.getNonReferenceType())))
return TemplateDeductionResult::NonDeducedMismatch;
return TemplateDeductionResult::Success;
}
template <class T>
static TemplateDeductionResult FinishTemplateArgumentDeduction(
Sema &S, FunctionTemplateDecl *FTD,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
TemplateDeductionInfo &Info, T &&CheckDeductionConsistency) {
EnterExpressionEvaluationContext Unevaluated(
S, Sema::ExpressionEvaluationContext::Unevaluated);
Sema::SFINAETrap Trap(S);
Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(FTD));
// C++26 [temp.deduct.type]p2:
// [...] or if any template argument remains neither deduced nor
// explicitly specified, template argument deduction fails.
bool IsIncomplete = false;
Sema::CheckTemplateArgumentInfo CTAI(/*PartialOrdering=*/true);
if (auto Result = ConvertDeducedTemplateArguments(
S, FTD, /*IsDeduced=*/true, Deduced, Info, CTAI,
/*CurrentInstantiationScope=*/nullptr,
/*NumAlreadyConverted=*/0, &IsIncomplete);
Result != TemplateDeductionResult::Success)
return Result;
// Form the template argument list from the deduced template arguments.
TemplateArgumentList *SugaredDeducedArgumentList =
TemplateArgumentList::CreateCopy(S.Context, CTAI.SugaredConverted);
TemplateArgumentList *CanonicalDeducedArgumentList =
TemplateArgumentList::CreateCopy(S.Context, CTAI.CanonicalConverted);
Info.reset(SugaredDeducedArgumentList, CanonicalDeducedArgumentList);
// Substitute the deduced template arguments into the argument
// and verify that the instantiated argument is both valid
// and equivalent to the parameter.
LocalInstantiationScope InstScope(S);
if (auto TDR = CheckDeductionConsistency(S, FTD, CTAI.SugaredConverted);
TDR != TemplateDeductionResult::Success)
return TDR;
return Trap.hasErrorOccurred() ? TemplateDeductionResult::SubstitutionFailure
: TemplateDeductionResult::Success;
}
/// Determine whether the function template \p FT1 is at least as
/// specialized as \p FT2.
static bool isAtLeastAsSpecializedAs(
Sema &S, SourceLocation Loc, FunctionTemplateDecl *FT1,
FunctionTemplateDecl *FT2, TemplatePartialOrderingContext TPOC,
ArrayRef<QualType> Args1, ArrayRef<QualType> Args2, bool Args1Offset) {
FunctionDecl *FD1 = FT1->getTemplatedDecl();
FunctionDecl *FD2 = FT2->getTemplatedDecl();
const FunctionProtoType *Proto1 = FD1->getType()->getAs<FunctionProtoType>();
const FunctionProtoType *Proto2 = FD2->getType()->getAs<FunctionProtoType>();
assert(Proto1 && Proto2 && "Function templates must have prototypes");
// C++26 [temp.deduct.partial]p3:
// The types used to determine the ordering depend on the context in which
// the partial ordering is done:
// - In the context of a function call, the types used are those function
// parameter types for which the function call has arguments.
// - In the context of a call to a conversion operator, the return types
// of the conversion function templates are used.
// - In other contexts (14.6.6.2) the function template's function type
// is used.
if (TPOC == TPOC_Other) {
// We wouldn't be partial ordering these candidates if these didn't match.
assert(Proto1->getMethodQuals() == Proto2->getMethodQuals() &&
Proto1->getRefQualifier() == Proto2->getRefQualifier() &&
Proto1->isVariadic() == Proto2->isVariadic() &&
"shouldn't partial order functions with different qualifiers in a "
"context where the function type is used");
assert(Args1.empty() && Args2.empty() &&
"Only call context should have arguments");
Args1 = Proto1->getParamTypes();
Args2 = Proto2->getParamTypes();
}
TemplateParameterList *TemplateParams = FT2->getTemplateParameters();
SmallVector<DeducedTemplateArgument, 4> Deduced(TemplateParams->size());
TemplateDeductionInfo Info(Loc);
bool HasDeducedAnyParamFromReturnType = false;
if (TPOC != TPOC_Call) {
if (DeduceTemplateArgumentsByTypeMatch(
S, TemplateParams, Proto2->getReturnType(), Proto1->getReturnType(),
Info, Deduced, TDF_None, PartialOrderingKind::Call,
/*DeducedFromArrayBound=*/false,
&HasDeducedAnyParamFromReturnType) !=
TemplateDeductionResult::Success)
return false;
}
llvm::SmallBitVector HasDeducedParam;
if (TPOC != TPOC_Conversion) {
HasDeducedParam.resize(Args2.size());
if (DeduceTemplateArguments(S, TemplateParams, Args2, Args1, Info, Deduced,
TDF_None, PartialOrderingKind::Call,
/*HasDeducedAnyParam=*/nullptr,
&HasDeducedParam) !=
TemplateDeductionResult::Success)
return false;
}
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
Sema::InstantiatingTemplate Inst(
S, Info.getLocation(), FT2, DeducedArgs,
Sema::CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
if (Inst.isInvalid())
return false;
bool AtLeastAsSpecialized;
S.runWithSufficientStackSpace(Info.getLocation(), [&] {
AtLeastAsSpecialized =
::FinishTemplateArgumentDeduction(
S, FT2, Deduced, Info,
[&](Sema &S, FunctionTemplateDecl *FTD,
ArrayRef<TemplateArgument> DeducedArgs) {
// As a provisional fix for a core issue that does not
// exist yet, which may be related to CWG2160, only check the
// consistency of parameters and return types which participated
// in deduction. We will still try to substitute them though.
if (TPOC != TPOC_Call) {
if (auto TDR = ::CheckDeductionConsistency(
S, FTD, /*ArgIdx=*/-1, Proto2->getReturnType(),
Proto1->getReturnType(), DeducedArgs,
/*CheckConsistency=*/HasDeducedAnyParamFromReturnType);
TDR != TemplateDeductionResult::Success)
return TDR;
}
if (TPOC == TPOC_Conversion)
return TemplateDeductionResult::Success;
return ::DeduceForEachType(
S, TemplateParams, Args2, Args1, Info, Deduced,
PartialOrderingKind::Call, /*FinishingDeduction=*/true,
[&](Sema &S, TemplateParameterList *, int ParamIdx,
int ArgIdx, QualType P, QualType A,
TemplateDeductionInfo &Info,
SmallVectorImpl<DeducedTemplateArgument> &Deduced,
PartialOrderingKind) {
if (ArgIdx != -1)
ArgIdx -= Args1Offset;
return ::CheckDeductionConsistency(
S, FTD, ArgIdx, P, A, DeducedArgs,
/*CheckConsistency=*/HasDeducedParam[ParamIdx]);
});
}) == TemplateDeductionResult::Success;
});
if (!AtLeastAsSpecialized)
return false;
// C++0x [temp.deduct.partial]p11:
// In most cases, all template parameters must have values in order for
// deduction to succeed, but for partial ordering purposes a template
// parameter may remain without a value provided it is not used in the
// types being used for partial ordering. [ Note: a template parameter used
// in a non-deduced context is considered used. -end note]
unsigned ArgIdx = 0, NumArgs = Deduced.size();
for (; ArgIdx != NumArgs; ++ArgIdx)
if (Deduced[ArgIdx].isNull())
break;
if (ArgIdx == NumArgs) {
// All template arguments were deduced. FT1 is at least as specialized
// as FT2.
return true;
}
// Figure out which template parameters were used.
llvm::SmallBitVector UsedParameters(TemplateParams->size());
switch (TPOC) {
case TPOC_Call:
for (unsigned I = 0, N = Args2.size(); I != N; ++I)
::MarkUsedTemplateParameters(S.Context, Args2[I], /*OnlyDeduced=*/false,
TemplateParams->getDepth(), UsedParameters);
break;
case TPOC_Conversion:
::MarkUsedTemplateParameters(S.Context, Proto2->getReturnType(),
/*OnlyDeduced=*/false,
TemplateParams->getDepth(), UsedParameters);
break;
case TPOC_Other:
// We do not deduce template arguments from the exception specification
// when determining the primary template of a function template
// specialization or when taking the address of a function template.
// Therefore, we do not mark template parameters in the exception
// specification as used during partial ordering to prevent the following
// from being ambiguous:
//
// template<typename T, typename U>
// void f(U) noexcept(noexcept(T())); // #1
//
// template<typename T>
// void f(T*) noexcept; // #2
//
// template<>
// void f<int>(int*) noexcept; // explicit specialization of #2
//
// Although there is no corresponding wording in the standard, this seems
// to be the intended behavior given the definition of
// 'deduction substitution loci' in [temp.deduct].
::MarkUsedTemplateParameters(
S.Context,
S.Context.getFunctionTypeWithExceptionSpec(FD2->getType(), EST_None),
/*OnlyDeduced=*/false, TemplateParams->getDepth(), UsedParameters);
break;
}
for (; ArgIdx != NumArgs; ++ArgIdx)
// If this argument had no value deduced but was used in one of the types
// used for partial ordering, then deduction fails.
if (Deduced[ArgIdx].isNull() && UsedParameters[ArgIdx])
return false;
return true;
}
enum class MoreSpecializedTrailingPackTieBreakerResult { Equal, Less, More };
// This a speculative fix for CWG1432 (Similar to the fix for CWG1395) that
// there is no wording or even resolution for this issue.
static MoreSpecializedTrailingPackTieBreakerResult
getMoreSpecializedTrailingPackTieBreaker(
const TemplateSpecializationType *TST1,
const TemplateSpecializationType *TST2) {
ArrayRef<TemplateArgument> As1 = TST1->template_arguments(),
As2 = TST2->template_arguments();
const TemplateArgument &TA1 = As1.back(), &TA2 = As2.back();
bool IsPack = TA1.getKind() == TemplateArgument::Pack;
assert(IsPack == (TA2.getKind() == TemplateArgument::Pack));
if (!IsPack)
return MoreSpecializedTrailingPackTieBreakerResult::Equal;
assert(As1.size() == As2.size());
unsigned PackSize1 = TA1.pack_size(), PackSize2 = TA2.pack_size();
bool IsPackExpansion1 =
PackSize1 && TA1.pack_elements().back().isPackExpansion();
bool IsPackExpansion2 =
PackSize2 && TA2.pack_elements().back().isPackExpansion();
if (PackSize1 == PackSize2 && IsPackExpansion1 == IsPackExpansion2)
return MoreSpecializedTrailingPackTieBreakerResult::Equal;
if (PackSize1 > PackSize2 && IsPackExpansion1)
return MoreSpecializedTrailingPackTieBreakerResult::More;
if (PackSize1 < PackSize2 && IsPackExpansion2)
return MoreSpecializedTrailingPackTieBreakerResult::Less;
return MoreSpecializedTrailingPackTieBreakerResult::Equal;
}
FunctionTemplateDecl *Sema::getMoreSpecializedTemplate(
FunctionTemplateDecl *FT1, FunctionTemplateDecl *FT2, SourceLocation Loc,
TemplatePartialOrderingContext TPOC, unsigned NumCallArguments1,
QualType RawObj1Ty, QualType RawObj2Ty, bool Reversed,
bool PartialOverloading) {
SmallVector<QualType> Args1;
SmallVector<QualType> Args2;
const FunctionDecl *FD1 = FT1->getTemplatedDecl();
const FunctionDecl *FD2 = FT2->getTemplatedDecl();
bool ShouldConvert1 = false;
bool ShouldConvert2 = false;
bool Args1Offset = false;
bool Args2Offset = false;
QualType Obj1Ty;
QualType Obj2Ty;
if (TPOC == TPOC_Call) {
const FunctionProtoType *Proto1 =
FD1->getType()->castAs<FunctionProtoType>();
const FunctionProtoType *Proto2 =
FD2->getType()->castAs<FunctionProtoType>();
// - In the context of a function call, the function parameter types are
// used.
const CXXMethodDecl *Method1 = dyn_cast<CXXMethodDecl>(FD1);
const CXXMethodDecl *Method2 = dyn_cast<CXXMethodDecl>(FD2);
// C++20 [temp.func.order]p3
// [...] Each function template M that is a member function is
// considered to have a new first parameter of type
// X(M), described below, inserted in its function parameter list.
//
// Note that we interpret "that is a member function" as
// "that is a member function with no expicit object argument".
// Otherwise the ordering rules for methods with expicit objet arguments
// against anything else make no sense.
bool NonStaticMethod1 = Method1 && !Method1->isStatic(),
NonStaticMethod2 = Method2 && !Method2->isStatic();
auto Params1Begin = Proto1->param_type_begin(),
Params2Begin = Proto2->param_type_begin();
size_t NumComparedArguments = NumCallArguments1;
if (auto OO = FD1->getOverloadedOperator();
(NonStaticMethod1 && NonStaticMethod2) ||
(OO != OO_None && OO != OO_Call && OO != OO_Subscript)) {
ShouldConvert1 =
NonStaticMethod1 && !Method1->hasCXXExplicitFunctionObjectParameter();
ShouldConvert2 =
NonStaticMethod2 && !Method2->hasCXXExplicitFunctionObjectParameter();
NumComparedArguments += 1;
if (ShouldConvert1) {
bool IsRValRef2 =
ShouldConvert2
? Method2->getRefQualifier() == RQ_RValue
: Proto2->param_type_begin()[0]->isRValueReferenceType();
// Compare 'this' from Method1 against first parameter from Method2.
Obj1Ty = GetImplicitObjectParameterType(this->Context, Method1,
RawObj1Ty, IsRValRef2);
Args1.push_back(Obj1Ty);
Args1Offset = true;
}
if (ShouldConvert2) {
bool IsRValRef1 =
ShouldConvert1
? Method1->getRefQualifier() == RQ_RValue
: Proto1->param_type_begin()[0]->isRValueReferenceType();
// Compare 'this' from Method2 against first parameter from Method1.
Obj2Ty = GetImplicitObjectParameterType(this->Context, Method2,
RawObj2Ty, IsRValRef1);
Args2.push_back(Obj2Ty);
Args2Offset = true;
}
} else {
if (NonStaticMethod1 && Method1->hasCXXExplicitFunctionObjectParameter())
Params1Begin += 1;
if (NonStaticMethod2 && Method2->hasCXXExplicitFunctionObjectParameter())
Params2Begin += 1;
}
Args1.insert(Args1.end(), Params1Begin, Proto1->param_type_end());
Args2.insert(Args2.end(), Params2Begin, Proto2->param_type_end());
// C++ [temp.func.order]p5:
// The presence of unused ellipsis and default arguments has no effect on
// the partial ordering of function templates.
Args1.resize(std::min(Args1.size(), NumComparedArguments));
Args2.resize(std::min(Args2.size(), NumComparedArguments));
if (Reversed)
std::reverse(Args2.begin(), Args2.end());
} else {
assert(!Reversed && "Only call context could have reversed arguments");
}
bool Better1 = isAtLeastAsSpecializedAs(*this, Loc, FT1, FT2, TPOC, Args1,
Args2, Args2Offset);
bool Better2 = isAtLeastAsSpecializedAs(*this, Loc, FT2, FT1, TPOC, Args2,
Args1, Args1Offset);
// C++ [temp.deduct.partial]p10:
// F is more specialized than G if F is at least as specialized as G and G
// is not at least as specialized as F.
if (Better1 != Better2) // We have a clear winner
return Better1 ? FT1 : FT2;
if (!Better1 && !Better2) // Neither is better than the other
return nullptr;
// C++ [temp.deduct.partial]p11:
// ... and if G has a trailing function parameter pack for which F does not
// have a corresponding parameter, and if F does not have a trailing
// function parameter pack, then F is more specialized than G.
SmallVector<QualType> Param1;
Param1.reserve(FD1->param_size() + ShouldConvert1);
if (ShouldConvert1)
Param1.push_back(Obj1Ty);
for (const auto &P : FD1->parameters())
Param1.push_back(P->getType());
SmallVector<QualType> Param2;
Param2.reserve(FD2->param_size() + ShouldConvert2);
if (ShouldConvert2)
Param2.push_back(Obj2Ty);
for (const auto &P : FD2->parameters())
Param2.push_back(P->getType());
unsigned NumParams1 = Param1.size();
unsigned NumParams2 = Param2.size();
bool Variadic1 =
FD1->param_size() && FD1->parameters().back()->isParameterPack();
bool Variadic2 =
FD2->param_size() && FD2->parameters().back()->isParameterPack();
if (Variadic1 != Variadic2) {
if (Variadic1 && NumParams1 > NumParams2)
return FT2;
if (Variadic2 && NumParams2 > NumParams1)
return FT1;
}
// Skip this tie breaker if we are performing overload resolution with partial
// arguments, as this breaks some assumptions about how closely related the
// candidates are.
for (int i = 0, e = std::min(NumParams1, NumParams2);
!PartialOverloading && i < e; ++i) {
QualType T1 = Param1[i].getCanonicalType();
QualType T2 = Param2[i].getCanonicalType();
auto *TST1 = dyn_cast<TemplateSpecializationType>(T1);
auto *TST2 = dyn_cast<TemplateSpecializationType>(T2);
if (!TST1 || !TST2)
continue;
switch (getMoreSpecializedTrailingPackTieBreaker(TST1, TST2)) {
case MoreSpecializedTrailingPackTieBreakerResult::Less:
return FT1;
case MoreSpecializedTrailingPackTieBreakerResult::More:
return FT2;
case MoreSpecializedTrailingPackTieBreakerResult::Equal:
continue;
}
llvm_unreachable(
"unknown MoreSpecializedTrailingPackTieBreakerResult value");
}
if (!Context.getLangOpts().CPlusPlus20)
return nullptr;
// Match GCC on not implementing [temp.func.order]p6.2.1.
// C++20 [temp.func.order]p6:
// If deduction against the other template succeeds for both transformed
// templates, constraints can be considered as follows:
// C++20 [temp.func.order]p6.1:
// If their template-parameter-lists (possibly including template-parameters
// invented for an abbreviated function template ([dcl.fct])) or function
// parameter lists differ in length, neither template is more specialized
// than the other.
TemplateParameterList *TPL1 = FT1->getTemplateParameters();
TemplateParameterList *TPL2 = FT2->getTemplateParameters();
if (TPL1->size() != TPL2->size() || NumParams1 != NumParams2)
return nullptr;
// C++20 [temp.func.order]p6.2.2:
// Otherwise, if the corresponding template-parameters of the
// template-parameter-lists are not equivalent ([temp.over.link]) or if the
// function parameters that positionally correspond between the two
// templates are not of the same type, neither template is more specialized
// than the other.
if (!TemplateParameterListsAreEqual(TPL1, TPL2, false,
Sema::TPL_TemplateParamsEquivalent))
return nullptr;
// [dcl.fct]p5:
// Any top-level cv-qualifiers modifying a parameter type are deleted when
// forming the function type.
for (unsigned i = 0; i < NumParams1; ++i)
if (!Context.hasSameUnqualifiedType(Param1[i], Param2[i]))
return nullptr;
// C++20 [temp.func.order]p6.3:
// Otherwise, if the context in which the partial ordering is done is
// that of a call to a conversion function and the return types of the
// templates are not the same, then neither template is more specialized
// than the other.
if (TPOC == TPOC_Conversion &&
!Context.hasSameType(FD1->getReturnType(), FD2->getReturnType()))
return nullptr;
llvm::SmallVector<const Expr *, 3> AC1, AC2;
FT1->getAssociatedConstraints(AC1);
FT2->getAssociatedConstraints(AC2);
bool AtLeastAsConstrained1, AtLeastAsConstrained2;
if (IsAtLeastAsConstrained(FT1, AC1, FT2, AC2, AtLeastAsConstrained1))
return nullptr;
if (IsAtLeastAsConstrained(FT2, AC2, FT1, AC1, AtLeastAsConstrained2))
return nullptr;
if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
return nullptr;
return AtLeastAsConstrained1 ? FT1 : FT2;
}
UnresolvedSetIterator Sema::getMostSpecialized(
UnresolvedSetIterator SpecBegin, UnresolvedSetIterator SpecEnd,
TemplateSpecCandidateSet &FailedCandidates,
SourceLocation Loc, const PartialDiagnostic &NoneDiag,
const PartialDiagnostic &AmbigDiag, const PartialDiagnostic &CandidateDiag,
bool Complain, QualType TargetType) {
if (SpecBegin == SpecEnd) {
if (Complain) {
Diag(Loc, NoneDiag);
FailedCandidates.NoteCandidates(*this, Loc);
}
return SpecEnd;
}
if (SpecBegin + 1 == SpecEnd)
return SpecBegin;
// Find the function template that is better than all of the templates it
// has been compared to.
UnresolvedSetIterator Best = SpecBegin;
FunctionTemplateDecl *BestTemplate
= cast<FunctionDecl>(*Best)->getPrimaryTemplate();
assert(BestTemplate && "Not a function template specialization?");
for (UnresolvedSetIterator I = SpecBegin + 1; I != SpecEnd; ++I) {
FunctionTemplateDecl *Challenger
= cast<FunctionDecl>(*I)->getPrimaryTemplate();
assert(Challenger && "Not a function template specialization?");
if (declaresSameEntity(getMoreSpecializedTemplate(BestTemplate, Challenger,
Loc, TPOC_Other, 0),
Challenger)) {
Best = I;
BestTemplate = Challenger;
}
}
// Make sure that the "best" function template is more specialized than all
// of the others.
bool Ambiguous = false;
for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
FunctionTemplateDecl *Challenger
= cast<FunctionDecl>(*I)->getPrimaryTemplate();
if (I != Best &&
!declaresSameEntity(getMoreSpecializedTemplate(BestTemplate, Challenger,
Loc, TPOC_Other, 0),
BestTemplate)) {
Ambiguous = true;
break;
}
}
if (!Ambiguous) {
// We found an answer. Return it.
return Best;
}
// Diagnose the ambiguity.
if (Complain) {
Diag(Loc, AmbigDiag);
// FIXME: Can we order the candidates in some sane way?
for (UnresolvedSetIterator I = SpecBegin; I != SpecEnd; ++I) {
PartialDiagnostic PD = CandidateDiag;
const auto *FD = cast<FunctionDecl>(*I);
PD << FD << getTemplateArgumentBindingsText(
FD->getPrimaryTemplate()->getTemplateParameters(),
*FD->getTemplateSpecializationArgs());
if (!TargetType.isNull())
HandleFunctionTypeMismatch(PD, FD->getType(), TargetType);
Diag((*I)->getLocation(), PD);
}
}
return SpecEnd;
}
FunctionDecl *Sema::getMoreConstrainedFunction(FunctionDecl *FD1,
FunctionDecl *FD2) {
assert(!FD1->getDescribedTemplate() && !FD2->getDescribedTemplate() &&
"not for function templates");
assert(!FD1->isFunctionTemplateSpecialization() ||
isa<CXXConversionDecl>(FD1));
assert(!FD2->isFunctionTemplateSpecialization() ||
isa<CXXConversionDecl>(FD2));
FunctionDecl *F1 = FD1;
if (FunctionDecl *P = FD1->getTemplateInstantiationPattern(false))
F1 = P;
FunctionDecl *F2 = FD2;
if (FunctionDecl *P = FD2->getTemplateInstantiationPattern(false))
F2 = P;
llvm::SmallVector<const Expr *, 1> AC1, AC2;
F1->getAssociatedConstraints(AC1);
F2->getAssociatedConstraints(AC2);
bool AtLeastAsConstrained1, AtLeastAsConstrained2;
if (IsAtLeastAsConstrained(F1, AC1, F2, AC2, AtLeastAsConstrained1))
return nullptr;
if (IsAtLeastAsConstrained(F2, AC2, F1, AC1, AtLeastAsConstrained2))
return nullptr;
if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
return nullptr;
return AtLeastAsConstrained1 ? FD1 : FD2;
}
/// Determine whether one partial specialization, P1, is at least as
/// specialized than another, P2.
///
/// \tparam TemplateLikeDecl The kind of P2, which must be a
/// TemplateDecl or {Class,Var}TemplatePartialSpecializationDecl.
/// \param T1 The injected-class-name of P1 (faked for a variable template).
/// \param T2 The injected-class-name of P2 (faked for a variable template).
template<typename TemplateLikeDecl>
static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2,
TemplateLikeDecl *P2,
TemplateDeductionInfo &Info) {
// C++ [temp.class.order]p1:
// For two class template partial specializations, the first is at least as
// specialized as the second if, given the following rewrite to two
// function templates, the first function template is at least as
// specialized as the second according to the ordering rules for function
// templates (14.6.6.2):
// - the first function template has the same template parameters as the
// first partial specialization and has a single function parameter
// whose type is a class template specialization with the template
// arguments of the first partial specialization, and
// - the second function template has the same template parameters as the
// second partial specialization and has a single function parameter
// whose type is a class template specialization with the template
// arguments of the second partial specialization.
//
// Rather than synthesize function templates, we merely perform the
// equivalent partial ordering by performing deduction directly on
// the template arguments of the class template partial
// specializations. This computation is slightly simpler than the
// general problem of function template partial ordering, because
// class template partial specializations are more constrained. We
// know that every template parameter is deducible from the class
// template partial specialization's template arguments, for
// example.
SmallVector<DeducedTemplateArgument, 4> Deduced;
// Determine whether P1 is at least as specialized as P2.
Deduced.resize(P2->getTemplateParameters()->size());
if (DeduceTemplateArgumentsByTypeMatch(
S, P2->getTemplateParameters(), T2, T1, Info, Deduced, TDF_None,
PartialOrderingKind::Call, /*DeducedFromArrayBound=*/false,
/*HasDeducedAnyParam=*/nullptr) != TemplateDeductionResult::Success)
return false;
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(),
Deduced.end());
Sema::InstantiatingTemplate Inst(S, Info.getLocation(), P2, DeducedArgs,
Info);
if (Inst.isInvalid())
return false;
const auto *TST1 = cast<TemplateSpecializationType>(T1);
Sema::SFINAETrap Trap(S);
TemplateDeductionResult Result;
S.runWithSufficientStackSpace(Info.getLocation(), [&] {
Result = ::FinishTemplateArgumentDeduction(
S, P2, /*IsPartialOrdering=*/true, TST1->template_arguments(), Deduced,
Info);
});
if (Result != TemplateDeductionResult::Success)
return false;
if (Trap.hasErrorOccurred())
return false;
return true;
}
namespace {
// A dummy class to return nullptr instead of P2 when performing "more
// specialized than primary" check.
struct GetP2 {
template <typename T1, typename T2,
std::enable_if_t<std::is_same_v<T1, T2>, bool> = true>
T2 *operator()(T1 *, T2 *P2) {
return P2;
}
template <typename T1, typename T2,
std::enable_if_t<!std::is_same_v<T1, T2>, bool> = true>
T1 *operator()(T1 *, T2 *) {
return nullptr;
}
};
// The assumption is that two template argument lists have the same size.
struct TemplateArgumentListAreEqual {
ASTContext &Ctx;
TemplateArgumentListAreEqual(ASTContext &Ctx) : Ctx(Ctx) {}
template <typename T1, typename T2,
std::enable_if_t<std::is_same_v<T1, T2>, bool> = true>
bool operator()(T1 *PS1, T2 *PS2) {
ArrayRef<TemplateArgument> Args1 = PS1->getTemplateArgs().asArray(),
Args2 = PS2->getTemplateArgs().asArray();
for (unsigned I = 0, E = Args1.size(); I < E; ++I) {
// We use profile, instead of structural comparison of the arguments,
// because canonicalization can't do the right thing for dependent
// expressions.
llvm::FoldingSetNodeID IDA, IDB;
Args1[I].Profile(IDA, Ctx);
Args2[I].Profile(IDB, Ctx);
if (IDA != IDB)
return false;
}
return true;
}
template <typename T1, typename T2,
std::enable_if_t<!std::is_same_v<T1, T2>, bool> = true>
bool operator()(T1 *Spec, T2 *Primary) {
ArrayRef<TemplateArgument> Args1 = Spec->getTemplateArgs().asArray(),
Args2 = Primary->getInjectedTemplateArgs(Ctx);
for (unsigned I = 0, E = Args1.size(); I < E; ++I) {
// We use profile, instead of structural comparison of the arguments,
// because canonicalization can't do the right thing for dependent
// expressions.
llvm::FoldingSetNodeID IDA, IDB;
Args1[I].Profile(IDA, Ctx);
// Unlike the specialization arguments, the injected arguments are not
// always canonical.
Ctx.getCanonicalTemplateArgument(Args2[I]).Profile(IDB, Ctx);
if (IDA != IDB)
return false;
}
return true;
}
};
} // namespace
/// Returns the more specialized template specialization between T1/P1 and
/// T2/P2.
/// - If IsMoreSpecialThanPrimaryCheck is true, T1/P1 is the partial
/// specialization and T2/P2 is the primary template.
/// - otherwise, both T1/P1 and T2/P2 are the partial specialization.
///
/// \param T1 the type of the first template partial specialization
///
/// \param T2 if IsMoreSpecialThanPrimaryCheck is true, the type of the second
/// template partial specialization; otherwise, the type of the
/// primary template.
///
/// \param P1 the first template partial specialization
///
/// \param P2 if IsMoreSpecialThanPrimaryCheck is true, the second template
/// partial specialization; otherwise, the primary template.
///
/// \returns - If IsMoreSpecialThanPrimaryCheck is true, returns P1 if P1 is
/// more specialized, returns nullptr if P1 is not more specialized.
/// - otherwise, returns the more specialized template partial
/// specialization. If neither partial specialization is more
/// specialized, returns NULL.
template <typename TemplateLikeDecl, typename PrimaryDel>
static TemplateLikeDecl *
getMoreSpecialized(Sema &S, QualType T1, QualType T2, TemplateLikeDecl *P1,
PrimaryDel *P2, TemplateDeductionInfo &Info) {
constexpr bool IsMoreSpecialThanPrimaryCheck =
!std::is_same_v<TemplateLikeDecl, PrimaryDel>;
bool Better1 = isAtLeastAsSpecializedAs(S, T1, T2, P2, Info);
if (IsMoreSpecialThanPrimaryCheck && !Better1)
return nullptr;
bool Better2 = isAtLeastAsSpecializedAs(S, T2, T1, P1, Info);
if (IsMoreSpecialThanPrimaryCheck && !Better2)
return P1;
// C++ [temp.deduct.partial]p10:
// F is more specialized than G if F is at least as specialized as G and G
// is not at least as specialized as F.
if (Better1 != Better2) // We have a clear winner
return Better1 ? P1 : GetP2()(P1, P2);
if (!Better1 && !Better2)
return nullptr;
switch (getMoreSpecializedTrailingPackTieBreaker(
cast<TemplateSpecializationType>(T1),
cast<TemplateSpecializationType>(T2))) {
case MoreSpecializedTrailingPackTieBreakerResult::Less:
return P1;
case MoreSpecializedTrailingPackTieBreakerResult::More:
return GetP2()(P1, P2);
case MoreSpecializedTrailingPackTieBreakerResult::Equal:
break;
}
if (!S.Context.getLangOpts().CPlusPlus20)
return nullptr;
// Match GCC on not implementing [temp.func.order]p6.2.1.
// C++20 [temp.func.order]p6:
// If deduction against the other template succeeds for both transformed
// templates, constraints can be considered as follows:
TemplateParameterList *TPL1 = P1->getTemplateParameters();
TemplateParameterList *TPL2 = P2->getTemplateParameters();
if (TPL1->size() != TPL2->size())
return nullptr;
// C++20 [temp.func.order]p6.2.2:
// Otherwise, if the corresponding template-parameters of the
// template-parameter-lists are not equivalent ([temp.over.link]) or if the
// function parameters that positionally correspond between the two
// templates are not of the same type, neither template is more specialized
// than the other.
if (!S.TemplateParameterListsAreEqual(TPL1, TPL2, false,
Sema::TPL_TemplateParamsEquivalent))
return nullptr;
if (!TemplateArgumentListAreEqual(S.getASTContext())(P1, P2))
return nullptr;
llvm::SmallVector<const Expr *, 3> AC1, AC2;
P1->getAssociatedConstraints(AC1);
P2->getAssociatedConstraints(AC2);
bool AtLeastAsConstrained1, AtLeastAsConstrained2;
if (S.IsAtLeastAsConstrained(P1, AC1, P2, AC2, AtLeastAsConstrained1) ||
(IsMoreSpecialThanPrimaryCheck && !AtLeastAsConstrained1))
return nullptr;
if (S.IsAtLeastAsConstrained(P2, AC2, P1, AC1, AtLeastAsConstrained2))
return nullptr;
if (AtLeastAsConstrained1 == AtLeastAsConstrained2)
return nullptr;
return AtLeastAsConstrained1 ? P1 : GetP2()(P1, P2);
}
ClassTemplatePartialSpecializationDecl *
Sema::getMoreSpecializedPartialSpecialization(
ClassTemplatePartialSpecializationDecl *PS1,
ClassTemplatePartialSpecializationDecl *PS2,
SourceLocation Loc) {
QualType PT1 = PS1->getInjectedSpecializationType();
QualType PT2 = PS2->getInjectedSpecializationType();
TemplateDeductionInfo Info(Loc);
return getMoreSpecialized(*this, PT1, PT2, PS1, PS2, Info);
}
bool Sema::isMoreSpecializedThanPrimary(
ClassTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
ClassTemplateDecl *Primary = Spec->getSpecializedTemplate();
QualType PrimaryT = Primary->getInjectedClassNameSpecialization();
QualType PartialT = Spec->getInjectedSpecializationType();
ClassTemplatePartialSpecializationDecl *MaybeSpec =
getMoreSpecialized(*this, PartialT, PrimaryT, Spec, Primary, Info);
if (MaybeSpec)
Info.clearSFINAEDiagnostic();
return MaybeSpec;
}
VarTemplatePartialSpecializationDecl *
Sema::getMoreSpecializedPartialSpecialization(
VarTemplatePartialSpecializationDecl *PS1,
VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc) {
// Pretend the variable template specializations are class template
// specializations and form a fake injected class name type for comparison.
assert(PS1->getSpecializedTemplate() == PS2->getSpecializedTemplate() &&
"the partial specializations being compared should specialize"
" the same template.");
TemplateName Name(PS1->getSpecializedTemplate());
QualType PT1 = Context.getTemplateSpecializationType(
Name, PS1->getTemplateArgs().asArray());
QualType PT2 = Context.getTemplateSpecializationType(
Name, PS2->getTemplateArgs().asArray());
TemplateDeductionInfo Info(Loc);
return getMoreSpecialized(*this, PT1, PT2, PS1, PS2, Info);
}
bool Sema::isMoreSpecializedThanPrimary(
VarTemplatePartialSpecializationDecl *Spec, TemplateDeductionInfo &Info) {
VarTemplateDecl *Primary = Spec->getSpecializedTemplate();
TemplateName Name(Primary);
QualType PrimaryT = Context.getTemplateSpecializationType(
Name, Primary->getInjectedTemplateArgs(Context));
QualType PartialT = Context.getTemplateSpecializationType(
Name, Spec->getTemplateArgs().asArray());
VarTemplatePartialSpecializationDecl *MaybeSpec =
getMoreSpecialized(*this, PartialT, PrimaryT, Spec, Primary, Info);
if (MaybeSpec)
Info.clearSFINAEDiagnostic();
return MaybeSpec;
}
bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
TemplateParameterList *P, TemplateDecl *PArg, TemplateDecl *AArg,
const DefaultArguments &DefaultArgs, SourceLocation ArgLoc,
bool PartialOrdering, bool *StrictPackMatch) {
// C++1z [temp.arg.template]p4: (DR 150)
// A template template-parameter P is at least as specialized as a
// template template-argument A if, given the following rewrite to two
// function templates...
// Rather than synthesize function templates, we merely perform the
// equivalent partial ordering by performing deduction directly on
// the template parameter lists of the template template parameters.
//
TemplateParameterList *A = AArg->getTemplateParameters();
Sema::InstantiatingTemplate Inst(
*this, ArgLoc, Sema::InstantiatingTemplate::PartialOrderingTTP(), PArg,
SourceRange(P->getTemplateLoc(), P->getRAngleLoc()));
if (Inst.isInvalid())
return false;
// Given an invented class template X with the template parameter list of
// A (including default arguments):
// - Each function template has a single function parameter whose type is
// a specialization of X with template arguments corresponding to the
// template parameters from the respective function template
SmallVector<TemplateArgument, 8> AArgs(A->getInjectedTemplateArgs(Context));
// Check P's arguments against A's parameter list. This will fill in default
// template arguments as needed. AArgs are already correct by construction.
// We can't just use CheckTemplateIdType because that will expand alias
// templates.
SmallVector<TemplateArgument, 4> PArgs(P->getInjectedTemplateArgs(Context));
{
TemplateArgumentListInfo PArgList(P->getLAngleLoc(),
P->getRAngleLoc());
for (unsigned I = 0, N = P->size(); I != N; ++I) {
// Unwrap packs that getInjectedTemplateArgs wrapped around pack
// expansions, to form an "as written" argument list.
TemplateArgument Arg = PArgs[I];
if (Arg.getKind() == TemplateArgument::Pack) {
assert(Arg.pack_size() == 1 && Arg.pack_begin()->isPackExpansion());
Arg = *Arg.pack_begin();
}
PArgList.addArgument(getTrivialTemplateArgumentLoc(
Arg, QualType(), P->getParam(I)->getLocation()));
}
PArgs.clear();
// C++1z [temp.arg.template]p3:
// If the rewrite produces an invalid type, then P is not at least as
// specialized as A.
CheckTemplateArgumentInfo CTAI(
/*PartialOrdering=*/false, /*MatchingTTP=*/true);
CTAI.SugaredConverted = std::move(PArgs);
if (CheckTemplateArgumentList(AArg, ArgLoc, PArgList, DefaultArgs,
/*PartialTemplateArgs=*/false, CTAI,
/*UpdateArgsWithConversions=*/true,
/*ConstraintsNotSatisfied=*/nullptr))
return false;
PArgs = std::move(CTAI.SugaredConverted);
if (StrictPackMatch)
*StrictPackMatch |= CTAI.StrictPackMatch;
}
// Determine whether P1 is at least as specialized as P2.
TemplateDeductionInfo Info(ArgLoc, A->getDepth());
SmallVector<DeducedTemplateArgument, 4> Deduced;
Deduced.resize(A->size());
// ... the function template corresponding to P is at least as specialized
// as the function template corresponding to A according to the partial
// ordering rules for function templates.
// Provisional resolution for CWG2398: Regarding temp.arg.template]p4, when
// applying the partial ordering rules for function templates on
// the rewritten template template parameters:
// - In a deduced context, the matching of packs versus fixed-size needs to
// be inverted between Ps and As. On non-deduced context, matching needs to
// happen both ways, according to [temp.arg.template]p3, but this is
// currently implemented as a special case elsewhere.
switch (::DeduceTemplateArguments(
*this, A, AArgs, PArgs, Info, Deduced,
/*NumberOfArgumentsMustMatch=*/false, /*PartialOrdering=*/true,
PartialOrdering ? PackFold::ArgumentToParameter : PackFold::Both,
/*HasDeducedAnyParam=*/nullptr)) {
case clang::TemplateDeductionResult::Success:
if (StrictPackMatch && Info.hasStrictPackMatch())
*StrictPackMatch = true;
break;
case TemplateDeductionResult::MiscellaneousDeductionFailure:
Diag(AArg->getLocation(), diag::err_template_param_list_different_arity)
<< (A->size() > P->size()) << /*isTemplateTemplateParameter=*/true
<< SourceRange(A->getTemplateLoc(), P->getRAngleLoc());
return false;
case TemplateDeductionResult::NonDeducedMismatch:
Diag(AArg->getLocation(), diag::err_non_deduced_mismatch)
<< Info.FirstArg << Info.SecondArg;
return false;
case TemplateDeductionResult::Inconsistent:
Diag(getAsNamedDecl(Info.Param)->getLocation(),
diag::err_inconsistent_deduction)
<< Info.FirstArg << Info.SecondArg;
return false;
case TemplateDeductionResult::AlreadyDiagnosed:
return false;
// None of these should happen for a plain deduction.
case TemplateDeductionResult::Invalid:
case TemplateDeductionResult::InstantiationDepth:
case TemplateDeductionResult::Incomplete:
case TemplateDeductionResult::IncompletePack:
case TemplateDeductionResult::Underqualified:
case TemplateDeductionResult::SubstitutionFailure:
case TemplateDeductionResult::DeducedMismatch:
case TemplateDeductionResult::DeducedMismatchNested:
case TemplateDeductionResult::TooManyArguments:
case TemplateDeductionResult::TooFewArguments:
case TemplateDeductionResult::InvalidExplicitArguments:
case TemplateDeductionResult::NonDependentConversionFailure:
case TemplateDeductionResult::ConstraintsNotSatisfied:
case TemplateDeductionResult::CUDATargetMismatch:
llvm_unreachable("Unexpected Result");
}
SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
TemplateDeductionResult TDK;
runWithSufficientStackSpace(Info.getLocation(), [&] {
TDK = ::FinishTemplateArgumentDeduction(*this, AArg, PartialOrdering, PArgs,
Deduced, Info);
});
switch (TDK) {
case TemplateDeductionResult::Success:
return true;
// It doesn't seem possible to get a non-deduced mismatch when partial
// ordering TTPs, except with an invalid template parameter list which has
// a parameter after a pack.
case TemplateDeductionResult::NonDeducedMismatch:
assert(PArg->isInvalidDecl() && "Unexpected NonDeducedMismatch");
return false;
// Substitution failures should have already been diagnosed.
case TemplateDeductionResult::AlreadyDiagnosed:
case TemplateDeductionResult::SubstitutionFailure:
case TemplateDeductionResult::InstantiationDepth:
return false;
// None of these should happen when just converting deduced arguments.
case TemplateDeductionResult::Invalid:
case TemplateDeductionResult::Incomplete:
case TemplateDeductionResult::IncompletePack:
case TemplateDeductionResult::Inconsistent:
case TemplateDeductionResult::Underqualified:
case TemplateDeductionResult::DeducedMismatch:
case TemplateDeductionResult::DeducedMismatchNested:
case TemplateDeductionResult::TooManyArguments:
case TemplateDeductionResult::TooFewArguments:
case TemplateDeductionResult::InvalidExplicitArguments:
case TemplateDeductionResult::NonDependentConversionFailure:
case TemplateDeductionResult::ConstraintsNotSatisfied:
case TemplateDeductionResult::MiscellaneousDeductionFailure:
case TemplateDeductionResult::CUDATargetMismatch:
llvm_unreachable("Unexpected Result");
}
llvm_unreachable("Unexpected TDK");
}
namespace {
struct MarkUsedTemplateParameterVisitor : DynamicRecursiveASTVisitor {
llvm::SmallBitVector &Used;
unsigned Depth;
MarkUsedTemplateParameterVisitor(llvm::SmallBitVector &Used,
unsigned Depth)
: Used(Used), Depth(Depth) { }
bool VisitTemplateTypeParmType(TemplateTypeParmType *T) override {
if (T->getDepth() == Depth)
Used[T->getIndex()] = true;
return true;
}
bool TraverseTemplateName(TemplateName Template) override {
if (auto *TTP = llvm::dyn_cast_or_null<TemplateTemplateParmDecl>(
Template.getAsTemplateDecl()))
if (TTP->getDepth() == Depth)
Used[TTP->getIndex()] = true;
DynamicRecursiveASTVisitor::TraverseTemplateName(Template);
return true;
}
bool VisitDeclRefExpr(DeclRefExpr *E) override {
if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
if (NTTP->getDepth() == Depth)
Used[NTTP->getIndex()] = true;
return true;
}
};
}
/// Mark the template parameters that are used by the given
/// expression.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
const Expr *E,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
if (!OnlyDeduced) {
MarkUsedTemplateParameterVisitor(Used, Depth)
.TraverseStmt(const_cast<Expr *>(E));
return;
}
// We can deduce from a pack expansion.
if (const PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(E))
E = Expansion->getPattern();
const NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(E, Depth);
if (!NTTP)
return;
if (NTTP->getDepth() == Depth)
Used[NTTP->getIndex()] = true;
// In C++17 mode, additional arguments may be deduced from the type of a
// non-type argument.
if (Ctx.getLangOpts().CPlusPlus17)
MarkUsedTemplateParameters(Ctx, NTTP->getType(), OnlyDeduced, Depth, Used);
}
/// Mark the template parameters that are used by the given
/// nested name specifier.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
NestedNameSpecifier *NNS,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
if (!NNS)
return;
MarkUsedTemplateParameters(Ctx, NNS->getPrefix(), OnlyDeduced, Depth,
Used);
MarkUsedTemplateParameters(Ctx, QualType(NNS->getAsType(), 0),
OnlyDeduced, Depth, Used);
}
/// Mark the template parameters that are used by the given
/// template name.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
TemplateName Name,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
if (TemplateTemplateParmDecl *TTP
= dyn_cast<TemplateTemplateParmDecl>(Template)) {
if (TTP->getDepth() == Depth)
Used[TTP->getIndex()] = true;
}
return;
}
if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName())
MarkUsedTemplateParameters(Ctx, QTN->getQualifier(), OnlyDeduced,
Depth, Used);
if (DependentTemplateName *DTN = Name.getAsDependentTemplateName())
MarkUsedTemplateParameters(Ctx, DTN->getQualifier(), OnlyDeduced,
Depth, Used);
}
/// Mark the template parameters that are used by the given
/// type.
static void
MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
if (T.isNull())
return;
// Non-dependent types have nothing deducible
if (!T->isDependentType())
return;
T = Ctx.getCanonicalType(T);
switch (T->getTypeClass()) {
case Type::Pointer:
MarkUsedTemplateParameters(Ctx,
cast<PointerType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::BlockPointer:
MarkUsedTemplateParameters(Ctx,
cast<BlockPointerType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::LValueReference:
case Type::RValueReference:
MarkUsedTemplateParameters(Ctx,
cast<ReferenceType>(T)->getPointeeType(),
OnlyDeduced,
Depth,
Used);
break;
case Type::MemberPointer: {
const MemberPointerType *MemPtr = cast<MemberPointerType>(T.getTypePtr());
MarkUsedTemplateParameters(Ctx, MemPtr->getPointeeType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(Ctx,
QualType(MemPtr->getQualifier()->getAsType(), 0),
OnlyDeduced, Depth, Used);
break;
}
case Type::DependentSizedArray:
MarkUsedTemplateParameters(Ctx,
cast<DependentSizedArrayType>(T)->getSizeExpr(),
OnlyDeduced, Depth, Used);
// Fall through to check the element type
[[fallthrough]];
case Type::ConstantArray:
case Type::IncompleteArray:
case Type::ArrayParameter:
MarkUsedTemplateParameters(Ctx,
cast<ArrayType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::Vector:
case Type::ExtVector:
MarkUsedTemplateParameters(Ctx,
cast<VectorType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentVector: {
const auto *VecType = cast<DependentVectorType>(T);
MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced, Depth,
Used);
break;
}
case Type::DependentSizedExtVector: {
const DependentSizedExtVectorType *VecType
= cast<DependentSizedExtVectorType>(T);
MarkUsedTemplateParameters(Ctx, VecType->getElementType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(Ctx, VecType->getSizeExpr(), OnlyDeduced,
Depth, Used);
break;
}
case Type::DependentAddressSpace: {
const DependentAddressSpaceType *DependentASType =
cast<DependentAddressSpaceType>(T);
MarkUsedTemplateParameters(Ctx, DependentASType->getPointeeType(),
OnlyDeduced, Depth, Used);
MarkUsedTemplateParameters(Ctx,
DependentASType->getAddrSpaceExpr(),
OnlyDeduced, Depth, Used);
break;
}
case Type::ConstantMatrix: {
const ConstantMatrixType *MatType = cast<ConstantMatrixType>(T);
MarkUsedTemplateParameters(Ctx, MatType->getElementType(), OnlyDeduced,
Depth, Used);
break;
}
case Type::DependentSizedMatrix: {
const DependentSizedMatrixType *MatType = cast<DependentSizedMatrixType>(T);
MarkUsedTemplateParameters(Ctx, MatType->getElementType(), OnlyDeduced,
Depth, Used);
MarkUsedTemplateParameters(Ctx, MatType->getRowExpr(), OnlyDeduced, Depth,
Used);
MarkUsedTemplateParameters(Ctx, MatType->getColumnExpr(), OnlyDeduced,
Depth, Used);
break;
}
case Type::FunctionProto: {
const FunctionProtoType *Proto = cast<FunctionProtoType>(T);
MarkUsedTemplateParameters(Ctx, Proto->getReturnType(), OnlyDeduced, Depth,
Used);
for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I) {
// C++17 [temp.deduct.type]p5:
// The non-deduced contexts are: [...]
// -- A function parameter pack that does not occur at the end of the
// parameter-declaration-list.
if (!OnlyDeduced || I + 1 == N ||
!Proto->getParamType(I)->getAs<PackExpansionType>()) {
MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
Depth, Used);
} else {
// FIXME: C++17 [temp.deduct.call]p1:
// When a function parameter pack appears in a non-deduced context,
// the type of that pack is never deduced.
//
// We should also track a set of "never deduced" parameters, and
// subtract that from the list of deduced parameters after marking.
}
}
if (auto *E = Proto->getNoexceptExpr())
MarkUsedTemplateParameters(Ctx, E, OnlyDeduced, Depth, Used);
break;
}
case Type::TemplateTypeParm: {
const TemplateTypeParmType *TTP = cast<TemplateTypeParmType>(T);
if (TTP->getDepth() == Depth)
Used[TTP->getIndex()] = true;
break;
}
case Type::SubstTemplateTypeParmPack: {
const SubstTemplateTypeParmPackType *Subst
= cast<SubstTemplateTypeParmPackType>(T);
if (Subst->getReplacedParameter()->getDepth() == Depth)
Used[Subst->getIndex()] = true;
MarkUsedTemplateParameters(Ctx, Subst->getArgumentPack(),
OnlyDeduced, Depth, Used);
break;
}
case Type::InjectedClassName:
T = cast<InjectedClassNameType>(T)->getInjectedSpecializationType();
[[fallthrough]];
case Type::TemplateSpecialization: {
const TemplateSpecializationType *Spec
= cast<TemplateSpecializationType>(T);
MarkUsedTemplateParameters(Ctx, Spec->getTemplateName(), OnlyDeduced,
Depth, Used);
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is
// not the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(Spec->template_arguments()))
break;
for (const auto &Arg : Spec->template_arguments())
MarkUsedTemplateParameters(Ctx, Arg, OnlyDeduced, Depth, Used);
break;
}
case Type::Complex:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<ComplexType>(T)->getElementType(),
OnlyDeduced, Depth, Used);
break;
case Type::Atomic:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<AtomicType>(T)->getValueType(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentName:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<DependentNameType>(T)->getQualifier(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentTemplateSpecialization: {
// C++14 [temp.deduct.type]p5:
// The non-deduced contexts are:
// -- The nested-name-specifier of a type that was specified using a
// qualified-id
//
// C++14 [temp.deduct.type]p6:
// When a type name is specified in a way that includes a non-deduced
// context, all of the types that comprise that type name are also
// non-deduced.
if (OnlyDeduced)
break;
const DependentTemplateSpecializationType *Spec
= cast<DependentTemplateSpecializationType>(T);
MarkUsedTemplateParameters(Ctx,
Spec->getDependentTemplateName().getQualifier(),
OnlyDeduced, Depth, Used);
for (const auto &Arg : Spec->template_arguments())
MarkUsedTemplateParameters(Ctx, Arg, OnlyDeduced, Depth, Used);
break;
}
case Type::TypeOf:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx, cast<TypeOfType>(T)->getUnmodifiedType(),
OnlyDeduced, Depth, Used);
break;
case Type::TypeOfExpr:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<TypeOfExprType>(T)->getUnderlyingExpr(),
OnlyDeduced, Depth, Used);
break;
case Type::Decltype:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<DecltypeType>(T)->getUnderlyingExpr(),
OnlyDeduced, Depth, Used);
break;
case Type::PackIndexing:
if (!OnlyDeduced) {
MarkUsedTemplateParameters(Ctx, cast<PackIndexingType>(T)->getPattern(),
OnlyDeduced, Depth, Used);
MarkUsedTemplateParameters(Ctx, cast<PackIndexingType>(T)->getIndexExpr(),
OnlyDeduced, Depth, Used);
}
break;
case Type::UnaryTransform:
if (!OnlyDeduced)
MarkUsedTemplateParameters(Ctx,
cast<UnaryTransformType>(T)->getUnderlyingType(),
OnlyDeduced, Depth, Used);
break;
case Type::PackExpansion:
MarkUsedTemplateParameters(Ctx,
cast<PackExpansionType>(T)->getPattern(),
OnlyDeduced, Depth, Used);
break;
case Type::Auto:
case Type::DeducedTemplateSpecialization:
MarkUsedTemplateParameters(Ctx,
cast<DeducedType>(T)->getDeducedType(),
OnlyDeduced, Depth, Used);
break;
case Type::DependentBitInt:
MarkUsedTemplateParameters(Ctx,
cast<DependentBitIntType>(T)->getNumBitsExpr(),
OnlyDeduced, Depth, Used);
break;
case Type::HLSLAttributedResource:
MarkUsedTemplateParameters(
Ctx, cast<HLSLAttributedResourceType>(T)->getWrappedType(), OnlyDeduced,
Depth, Used);
if (cast<HLSLAttributedResourceType>(T)->hasContainedType())
MarkUsedTemplateParameters(
Ctx, cast<HLSLAttributedResourceType>(T)->getContainedType(),
OnlyDeduced, Depth, Used);
break;
// None of these types have any template parameters in them.
case Type::Builtin:
case Type::VariableArray:
case Type::FunctionNoProto:
case Type::Record:
case Type::Enum:
case Type::ObjCInterface:
case Type::ObjCObject:
case Type::ObjCObjectPointer:
case Type::UnresolvedUsing:
case Type::Pipe:
case Type::BitInt:
#define TYPE(Class, Base)
#define ABSTRACT_TYPE(Class, Base)
#define DEPENDENT_TYPE(Class, Base)
#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
#include "clang/AST/TypeNodes.inc"
break;
}
}
/// Mark the template parameters that are used by this
/// template argument.
static void
MarkUsedTemplateParameters(ASTContext &Ctx,
const TemplateArgument &TemplateArg,
bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
switch (TemplateArg.getKind()) {
case TemplateArgument::Null:
case TemplateArgument::Integral:
case TemplateArgument::Declaration:
case TemplateArgument::NullPtr:
case TemplateArgument::StructuralValue:
break;
case TemplateArgument::Type:
MarkUsedTemplateParameters(Ctx, TemplateArg.getAsType(), OnlyDeduced,
Depth, Used);
break;
case TemplateArgument::Template:
case TemplateArgument::TemplateExpansion:
MarkUsedTemplateParameters(Ctx,
TemplateArg.getAsTemplateOrTemplatePattern(),
OnlyDeduced, Depth, Used);
break;
case TemplateArgument::Expression:
MarkUsedTemplateParameters(Ctx, TemplateArg.getAsExpr(), OnlyDeduced,
Depth, Used);
break;
case TemplateArgument::Pack:
for (const auto &P : TemplateArg.pack_elements())
MarkUsedTemplateParameters(Ctx, P, OnlyDeduced, Depth, Used);
break;
}
}
void
Sema::MarkUsedTemplateParameters(const Expr *E, bool OnlyDeduced,
unsigned Depth,
llvm::SmallBitVector &Used) {
::MarkUsedTemplateParameters(Context, E, OnlyDeduced, Depth, Used);
}
void
Sema::MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
bool OnlyDeduced, unsigned Depth,
llvm::SmallBitVector &Used) {
// C++0x [temp.deduct.type]p9:
// If the template argument list of P contains a pack expansion that is not
// the last template argument, the entire template argument list is a
// non-deduced context.
if (OnlyDeduced &&
hasPackExpansionBeforeEnd(TemplateArgs.asArray()))
return;
for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
::MarkUsedTemplateParameters(Context, TemplateArgs[I], OnlyDeduced,
Depth, Used);
}
void Sema::MarkUsedTemplateParameters(ArrayRef<TemplateArgument> TemplateArgs,
unsigned Depth,
llvm::SmallBitVector &Used) {
for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
::MarkUsedTemplateParameters(Context, TemplateArgs[I],
/*OnlyDeduced=*/false, Depth, Used);
}
void Sema::MarkDeducedTemplateParameters(
ASTContext &Ctx, const FunctionTemplateDecl *FunctionTemplate,
llvm::SmallBitVector &Deduced) {
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
Deduced.clear();
Deduced.resize(TemplateParams->size());
FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
for (unsigned I = 0, N = Function->getNumParams(); I != N; ++I)
::MarkUsedTemplateParameters(Ctx, Function->getParamDecl(I)->getType(),
true, TemplateParams->getDepth(), Deduced);
}
bool hasDeducibleTemplateParameters(Sema &S,
FunctionTemplateDecl *FunctionTemplate,
QualType T) {
if (!T->isDependentType())
return false;
TemplateParameterList *TemplateParams
= FunctionTemplate->getTemplateParameters();
llvm::SmallBitVector Deduced(TemplateParams->size());
::MarkUsedTemplateParameters(S.Context, T, true, TemplateParams->getDepth(),
Deduced);
return Deduced.any();
}
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