Reapplies #104458, fixing a bug that occurs when a class member access expression calls an `operator->` operator function that returns a non-dependent class type.
Fixes#116932
- Remove the quotation marks in the diagnostic message for
err_ext_vector_component_name_illegal
- Pass in the quotation marks directly when reporting an illegal vector
component name inside `CheckExtVectorComponent`
- Add an offset to the `OpLoc` passed into `S.Diag` so the error message
arrow points directly to the offending illegal component rather than to
the '.' at the start of the component identifier.
- Modify the `vector-bool.cpp` element-wise access test case so it
(correctly) now only expects a single set of quotes.
This is a rebase of #95112 with my own feedback apply as @MitalAshok has
been inactive for a while.
It's fairly important this makes clang 20 as it is a blocker for #107451
---
[CWG2813](https://cplusplus.github.io/CWG/issues/2813.html)
prvalue.member_fn(expression-list) now will not materialize a temporary
for prvalue if member_fn is an explicit object member function, and
prvalue will bind directly to the object parameter.
The E1 in E1.static_member is now a discarded-value expression, so if E1
was a call to a [[nodiscard]] function, there will now be a warning.
This also affects C++98 with [[gnu::warn_unused_result]] functions.
This should not affect C where TemporaryMaterializationConversion is a
no-op.
Closes#100314Fixes#100341
---------
Co-authored-by: Mital Ashok <mital@mitalashok.co.uk>
The original code assumed that only special methods might be defined as
defaulted. Since C++20 comparison operators might be defaulted too, and
we *do* want to consider those as using the fields of the class.
Fixes: #116961
This commit addresses several Static Analyzer issues related to
potential null dereference by replacing dyn_cast<> with cast<> and
getAs<> with castAs<> in various parts of the codes.
The cast function asserts that the cast is valid, ensuring that the
pointer is not null and preventing null dereference errors.
The changes are made in the following files:
CGBuiltin.cpp: Ensure vector types have exactly 3 elements.
CGExpr.cpp: Ensure member declarations are field declarations.
AnalysisBasedWarnings.cpp: Ensure operations are member expressions.
SemaExprMember.cpp: Ensure base types are extended vector types.
These changes ensure that the types are correctly cast and prevent
potential null dereference issues, improving the robustness and safety
of the code.
A class member named by an expression in a member function that may instantiate to a static _or_ non-static member is represented by a `UnresolvedLookupExpr` in order to defer the implicit transformation to a class member access expression until instantiation. Since `ASTContext::getDecltypeType` only creates a `DecltypeType` that has a `DependentDecltypeType` as its canonical type when the operand is instantiation dependent, and since we do not transform types unless they are instantiation dependent, we need to mark the `UnresolvedLookupExpr` as instantiation dependent in order to correctly build a `DecltypeType` using the expression as its operand with a `DependentDecltypeType` canonical type. Fixes#99873.
This reverts commit ce4aada6e2135e29839f672a6599db628b53295d and a
follow-up patch 8ef26f1289bf069ccc0d6383f2f4c0116a1206c1.
This new warning can not be fully suppressed by the
`-Wno-missing-dependent-template-keyword` flag, this gives developer no
time to do the cleanup in a large codebase, see https://github.com/llvm/llvm-project/pull/98547#issuecomment-2228250884
Reapplies #92957, fixing an instance where the `template` keyword was
missing prior to a dependent name in `llvm/ADT/ArrayRef.h`. An
_alias-declaration_ is used to work around a bug affecting GCC releases
before 11.1 (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94799) which
rejects the use of the `template` keyword prior to the
_nested-name-specifier_ in the class member access.
CWG1835 was one of the many core issues resolved by P1787R6: "Declarations and where to
find them" (http://wg21.link/p1787r6). Its resolution changes how
member-qualified names (as defined by [basic.lookup.qual.general] p2) are looked
up. This patch implementation that resolution.
Previously, an _identifier_ following `.` or `->` would be first looked
up in the type of the object expression (i.e. qualified lookup), and
then in the context of the _postfix-expression_ (i.e. unqualified
lookup) if nothing was found; the result of the second lookup was
required to name a class template. Notably, this second lookup would
occur even when the object expression was dependent, and its result
would be used to determine whether a `<` token is the start of a
_template-argument_list_.
The new wording in [basic.lookup.qual.general] p2 states:
> A member-qualified name is the (unique) component name, if any, of
> - an _unqualified-id_ or
> - a _nested-name-specifier_ of the form _`type-name ::`_ or
_`namespace-name ::`_
>
> in the id-expression of a class member access expression. A
***qualified name*** is
> - a member-qualified name or
> - the terminal name of
> - a _qualified-id_,
> - a _using-declarator_,
> - a _typename-specifier_,
> - a _qualified-namespace-specifier_, or
> - a _nested-name-specifier_, _elaborated-type-specifier_, or
_class-or-decltype_ that has a _nested-name-specifier_.
>
> The _lookup context_ of a member-qualified name is the type of its
associated object expression (considered dependent if the object
expression is type-dependent). The lookup context of any other qualified
name is the type, template, or namespace nominated by the preceding
_nested-name-specifier_.
And [basic.lookup.qual.general] p3 now states:
> _Qualified name lookup_ in a class, namespace, or enumeration performs
a search of the scope associated with it except as specified below.
Unless otherwise specified, a qualified name undergoes qualified name
lookup in its lookup context from the point where it appears unless the
lookup context either is dependent and is not the current instantiation
or is not a class or class template. If nothing is found by qualified
lookup for a member-qualified name that is the terminal name of a
_nested-name-specifier_ and is not dependent, it undergoes unqualified
lookup.
In non-standardese terms, these two paragraphs essentially state the
following:
- A name that immediately follows `.` or `->` in a class member access
expression is a member-qualified name
- A member-qualified name will be first looked up in the type of the
object expression `T` unless `T` is a dependent type that is _not_ the
current instantiation, e.g.
```
template<typename T>
struct A
{
void f(T* t)
{
this->x; // type of the object expression is 'A<T>'. although 'A<T>' is dependent, it is the
// current instantiation so we look up 'x' in the template definition context.
t->y; // type of the object expression is 'T' ('->' is transformed to '.' per [expr.ref]).
// 'T' is dependent and is *not* the current instantiation, so we lookup 'y' in the
// template instantiation context.
}
};
```
- If the first lookup finds nothing and:
- the member-qualified name is the first component of a
_nested-name-specifier_ (which could be an _identifier_ or a
_simple-template-id_), and either:
- the type of the object expression is the current instantiation and it
has no dependent base classes, or
- the type of the object expression is not dependent
then we lookup the name again, this time via unqualified lookup.
Although the second (unqualified) lookup is stated not to occur when the
member-qualified name is dependent, a dependent name will _not_ be
dependent once the template is instantiated, so the second lookup must
"occur" during instantiation if qualified lookup does not find anything.
This means that we must perform the second (unqualified) lookup during
parsing even when the type of the object expression is dependent, but
those results are _not_ used to determine whether a `<` token is the
start of a _template-argument_list_; they are stored so we can replicate
the second lookup during instantiation.
In even simpler terms (paraphrasing the meeting minutes from the review of P1787; see https://wiki.edg.com/bin/view/Wg21summer2020/P1787%28Lookup%29Review2020-06-15Through2020-06-18):
- Unqualified lookup always happens for the first name in a
_nested-name-specifier_ that follows `.` or `->`
- The result of that lookup is only used to determine whether `<` is the
start of a _template-argument-list_ if the first (qualified) lookup
found nothing and the lookup context:
- is not dependent, or
- is the current instantiation and has no dependent base classes.
An example:
```
struct A
{
void f();
};
template<typename T>
using B = A;
template<typename T>
struct C : A
{
template<typename U>
void g();
void h(T* t)
{
this->g<int>(); // ok, '<' is the start of a template-argument-list ('g' was found via qualified lookup in the current instantiation)
this->B<void>::f(); // ok, '<' is the start of a template-argument-list (current instantiation has no dependent bases, 'B' was found via unqualified lookup)
t->g<int>(); // error: '<' means less than (unqualified lookup does not occur for a member-qualified name that isn't the first component of a nested-name-specifier)
t->B<void>::f(); // error: '<' means less than (unqualified lookup does not occur if the name is dependent)
t->template B<void>::f(); // ok: '<' is the start of a template-argument-list ('template' keyword used)
}
};
```
Some additional notes:
- Per [basic.lookup.qual.general] p1, lookup for a
member-qualified name only considers namespaces, types, and templates
whose specializations are types if it's an _identifier_ followed by
`::`; lookup for the component name of a _simple-template-id_ followed
by `::` is _not_ subject to this rule.
- The wording which specifies when the second unqualified lookup occurs
appears to be paradoxical. We are supposed to do it only for the first
component name of a _nested-name-specifier_ that follows `.` or `->`
when qualified lookup finds nothing. However, when that name is followed
by `<` (potentially starting a _simple-template-id_) we don't _know_
whether it will be the start of a _nested-name-specifier_ until we do
the lookup -- but we aren't supposed to do the lookup until we know it's
part of a _nested-name-specifier_! ***However***, since we only do the
second lookup when the first lookup finds nothing (and the name isn't
dependent), ***and*** since neither lookup is type-only, the only valid
option is for the name to be the _template-name_ in a
_simple-template-id_ that is followed by `::` (it can't be an
_unqualified-id_ naming a member because we already determined that the
lookup context doesn't have a member with that name). Thus, we can lock
into the _nested-name-specifier_ interpretation and do the second lookup
without having to know whether the _simple-template-id_ will be followed
by `::` yet.
The following code causes an assert in `SemaExprMember.cpp` on line 981
to fail:
```
struct A { };
struct B;
void f(A *x) {
x->B::y; // crash here
}
```
This happens because we only return early from
`BuildMemberReferenceExpr` when the `CXXScopeSpecifier` is invalid
_before_ the lookup is performed. Since the lookup may invalidate the
`CXXScopeSpecifier` (e.g. if the _nested-name-specifier_ is incomplete),
this results in the second `BuildMemberReferenceExpr` overload being
called with an invalid `CXXScopeSpecifier`, which causes the assert to
fail. This patch moves the early return for invalid `CXXScopeSpecifiers`
to occur _after_ lookup is performed. This fixes#92972.
I also removed the `if (SS.isSet() && SS.isInvalid())` check in
`ActOnMemberAccessExpr` because the condition can never be true (`isSet`
returns `getScopeRep() != nullptr` and `isInvalid` returns
`Range.isValid() && getScopeRep() == nullptr`).
This patch moves documentation of `Sema` functions from `.cpp` files to `Sema.h` when there was no documentation in the latter, or it can be trivially subsumed. More complicated cases when there's less trivial divergence between documentation attached to declaration and the one attached to implementation are left for a later PR that would require review.
It appears that doxygen can find the documentation for a function defined out-of-line even if it's attached to an implementation, and not declaration. But other tools, e.g. clangd, are not as powerful. So this patch significantly improves autocompletion experience for (at least) clangd-based IDEs.
This patch improves the preservation of qualifiers and loss of type
sugar in TemplateNames.
This problem is analogous to https://reviews.llvm.org/D112374 and this
patch takes a very similar approach to that patch, except the impact
here is much lesser.
When a TemplateName was written bare, without qualifications, we
wouldn't produce a QualifiedTemplate which could be used to disambiguate
it from a Canonical TemplateName. This had effects in the TemplateName
printer, which had workarounds to deal with this, and wouldn't print the
TemplateName as-written in most situations.
There are also some related fixes to help preserve this type sugar along
the way into diagnostics, so that this patch can be properly tested.
- Fix dropping the template keyword.
- Fix type deduction to preserve sugar in TST TemplateNames.
#90152 introduced a bug that occurs when typo-correction attempts to fix a reference to a
non-existent member of the current instantiation (even though
`operator->` may return a different type than the object type). This
patch fixes it by simply considering the object expression to be of type
`ASTContext::DependentTy` when the arrow operator is used with a
dependent non-pointer non-function operand (after any implicit
conversions).
Reapplies #84050, addressing a bug which cases a crash when an
expression with the type of the current instantiation is used as the
_postfix-expression_ in a class member access expression (arrow form).
Consider the following:
```cpp
template<typename T>
struct A
{
auto f()
{
return this->x;
}
};
```
Although `A` has no dependent base classes and the lookup context for
`x` is the current instantiation, we currently do not diagnose the
absence of a member `x` until `A<T>::f` is instantiated. This patch
moves the point of diagnosis for such expressions to occur at the point
of definition (i.e. prior to instantiation).
Reapplies #87541 and #88311 (again) addressing the bug which caused
expressions naming overload sets to be incorrectly rebuilt, as well as
the bug which caused base class members to always be treated as overload
sets.
The primary change since #88311 is `UnresolvedLookupExpr::Create` is called directly in `BuildPossibleImplicitMemberExpr` with `KnownDependent` as `true` (which causes the expression type to be set to `ASTContext::DependentTy`). This ensures that any further semantic analysis involving the type of the potentially implicit class member access expression is deferred until instantiation.
This patch converts the enum into scoped enum, and moves it into its own header for the time being. It's definition is needed in `Sema.h`, and is going to be needed in upcoming `SemaObjC.h`. `Lookup.h` can't hold it, because it includes `Sema.h`.
This patch fixes a crash that happens when '`this`' is referenced
(implicitly or explicitly) in a dependent class scope function template
specialization that instantiates to a static member function. For
example:
```
template<typename T>
struct A
{
template<typename U>
static void f();
template<>
void f<int>()
{
this; // causes crash during instantiation
}
};
template struct A<int>;
```
This happens because during instantiation of the function body,
`Sema::getCurrentThisType` will return a null `QualType` which we
rebuild the `CXXThisExpr` with. A similar problem exists for implicit
class member access expressions in such contexts (which shouldn't really
happen within templates anyways per [class.mfct.non.static]
p2, but changing that is non-trivial). This patch fixes the crash by building
`UnresolvedLookupExpr`s instead of `MemberExpr`s for these implicit
member accesses, which will then be correctly rebuilt as `MemberExpr`s
during instantiation.
Fixes: #77583
bcd51aaaf8bde4b0ae7a4155d9ce3dec78fe2598 fixed part of template
instantiation dependent name issues but still missing some cases This
patch want to enhance the dependent name check
HLSL supports vector swizzles on scalars by implicitly converting the
scalar to a single-element vector. This syntax is a convienent way to
initialize vectors based on filling a scalar value.
There are two parts of this change. The first part in the Lexer splits
numeric constant tokens when a `.x` or `.r` suffix is encountered. This
splitting is a bit hacky but allows the numeric constant to be parsed
separately from the vector element expression. There is an ambiguity
here with the `r` suffix used by fixed point types, however fixed point
types aren't supported in HLSL so this should not cause any exposable
problems (a separate issue has been filed to track validating language
options for HLSL: #67689).
The second part of this change is in Sema::LookupMemberExpr. For HLSL,
if the base type is a scalar, we implicit cast the scalar to a
one-element vector then call back to perform the vector lookup.
Fixes#56658 and #67511
The goal of this change is to clean up some of the code surrounding
HLSL using CXXThisExpr as a non-pointer l-value. This change cleans up
a bunch of assumptions and inconsistencies around how the type of
`this` is handled through the AST and code generation.
This change is be mostly NFC for HLSL, and completely NFC for other
language modes.
This change introduces a new member to query for the this object's type
and seeks to clarify the normal usages of the this type.
With the introudction of HLSL to clang, CXXThisExpr may now be an
l-value and behave like a reference type rather than C++'s normal
method of it being an r-value of pointer type.
With this change there are now three ways in which a caller might need
to query the type of `this`:
* The type of the `CXXThisExpr`
* The type of the object `this` referrs to
* The type of the implicit (or explicit) `this` argument
This change codifies those three ways you may need to query
respectively as:
* CXXMethodDecl::getThisType()
* CXXMethodDecl::getThisObjectType()
* CXXMethodDecl::getThisArgType()
This change then revisits all uses of `getThisType()`, and in cases
where the only use was to resolve the pointee type, it replaces the
call with `getThisObjectType()`. In other cases it evaluates whether
the desired returned type is the type of the `this` expr, or the type
of the `this` function argument. The `this` expr type is used for
creating additional expr AST nodes and for member lookup, while the
argument type is used mostly for code generation.
Additionally some cases that used `getThisType` in simple queries could
be substituted for `getThisObjectType`. Since `getThisType` is
implemented in terms of `getThisObjectType` calling the later should be
more efficient if the former isn't needed.
Reviewed By: aaron.ballman, bogner
Differential Revision: https://reviews.llvm.org/D159247
ExtVectorElementExpr
This fixes a bug where an lvalue ExtVectorElementExpr was created when
the base expression was an ObjC property dot operator.
This reverts 220d08d942ab0df3211388e602ed34fa6139ca61.
Differential Revision: https://reviews.llvm.org/D138058
This change makes `this` a reference instead of a pointer in
HLSL. HLSL does not have the `->` operator, and accesses through `this`
are with the `.` syntax.
Tests were added and altered to make sure
the AST accurately reflects the types.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D135721
HLSL does not support pointers or references. This change generates
errors in sema for generating pointer, and reference types as well as
common operators (address-of, dereference, arrow), which are used with
pointers and are unsupported in HLSL.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D123167
We started diagnosing this situation with a more clear diagnostic
message, but it was pointed out that unevaluated contexts don't really
have the undefined behavior property as there is no runtime access
involved.
This augments the changes in https://reviews.llvm.org/D122656 to not
diagnose in an unevaluated context.
Member access for an atomic structure or union is unconditional
undefined behavior (C11 6.5.2.3p5). However, we would issue a confusing
error message about the base expression not being a structure or union
type.
GCC issues a warning for this case. Clang now warns as well, but the
warning is defaulted to an error because the actual access is still
unsafe.
This fixes Issue 54563.
This is the `ext_vector_type` alternative to D81083.
This patch extends Clang to allow 'bool' as a valid vector element type
(attribute ext_vector_type) in C/C++.
This is intended as the canonical type for SIMD masks and facilitates
clean vector intrinsic declarations. Vectors of i1 are supported on IR
level and below down to many SIMD ISAs, such as AVX512, ARM SVE (fixed
vector length) and the VE target (NEC SX-Aurora TSUBASA).
The RFC on cfe-dev: https://lists.llvm.org/pipermail/cfe-dev/2020-May/065434.html
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D88905
If this is a SFINAE context, then continuing to look up names
(in particular, to treat a non-function as a function, and then
do ADL) might too-eagerly complete a type that it's not safe to
complete right now. We should just say "okay, that's a substitution
failure" and not do any more work than absolutely required.
Fixes#52970.
Differential Revision: https://reviews.llvm.org/D117603
If this is a SFINAE context, then continuing to look up names
(in particular, to treat a non-function as a function, and then
do ADL) might too-eagerly complete a type that it's not safe to
complete right now. We should just say "okay, that's a substitution
failure" and not do any more work than absolutely required.
Fixes#52970.
Differential Revision: https://reviews.llvm.org/D117603
