The approved resolution for CWG2858 changes
[expr.prim.id.qual] p2 sentence 2 to read:
> A declarative _nested-name-specifier_ shall not have a
_computed-type-specifier_.
This patch implements the approved resolution. Since we don't consider
_nested-name-specifiers_ in friend declarations to be declarative (yet),
it currently isn't possible to write a test that would produce this
diagnostic (`diagnoseQualifiedDeclaration` is never called if the
`DeclContext` can't be computed). Nevertheless, tests were added which
will produce the diagnostic once we start calling
`diagnoseQualifiedDeclaration` for friend declarations.
The compiler doesn't know in advance if the streaming and non-streaming
vector-lengths are different, so it should be safe to give a warning
diagnostic to warn the user about possible undefined behaviour. If the
user knows the vector lengths are equal, they can disable the warning
separately.
Try to fix https://github.com/llvm/llvm-project/issues/86790
`getFETokenInfo` requires `DeclarationName` shouldn't be empty and this
will produce crash when checking name conflict of an anonymous
`NamedDecl` in `Sema::PushOnScopeChains` and whether it's a reserved
identifier or not. These wouldn't happen when it's a anonymous enum and
we can skip the checking and just add the declaration to current scope.
Co-authored-by: huqizhi <836744285@qq.com>
Emit `-Wunused-but-set-variable` warning on C++ variables whose
declaration (with initializer) entirely consist the condition expression
of a if/while/for construct but are not actually used in the body of the
if/while/for construct.
Fixes#41447
Clang erroneously rejects the following:
```
template<typename T>
struct A
{
template<typename U>
auto f();
};
template<>
template<typename U>
auto A<int>::f(); // error: conflicting types for 'f'
```
This happens because the explicit specialization of `f` has its return
type replaced with a dependent `AutoType` in `ActOnFunctionDeclarator`,
but no such replacement occurs for the implicitly instantiated function
template `A<int>::f`. Since the return types don't match, the explicit
specialization is diagnosed as an invalid redeclaration.
This patch moves the replacement of the return type to
`CheckFunctionDeclaration` so it also happens during instantiation.
`setObjectOfFriendDecl` will have been called by then, so the `isFriend
&& CurContext->isDependentContext()` condition is made redundant &
removed (as it already happens in `DeclContext::isDependentContext`).
`Sema::IsOverload` only checks the _declared_ return type (which isn't
changed by the adjustment), so adjusting the return type afterwards
should be safe.
This is now allowed in C23; continue to diagnose it in earlier language
modes as before, but now as a C23 extension rather than a GNU extension.
This fixes#83658.
Introduce `Decl::isFromExplicitGlobalModule` to replace the
`D->getOwningModule() && D->getOwningModule()->isExplicitGlobalModule()`
pattern to save some typings.
This reverts commit ca4c4a6758d184f209cb5d88ef42ecc011b11642.
This was intended not to introduce new consistency diagnostics for
smart pointer types, but failed to ignore sugar around types when
detecting this.
Fixed and test added.
GNU and MSVC have extensions where flexible array members (or their
equivalent) can be in unions or alone in structs. This is already fully
supported in Clang through the 0-sized array ("fake flexible array")
extension or when C99 flexible array members have been syntactically
obfuscated.
Clang needs to explicitly allow these extensions directly for C99
flexible arrays, since they are common code patterns in active use by
the
Linux kernel (and other projects). Such projects have been using either
0-sized arrays (which is considered deprecated in favor of C99 flexible
array members) or via obfuscated syntax, both of which complicate their
code bases.
For example, these do not error by default:
```
union one {
int a;
int b[0];
};
union two {
int a;
struct {
struct { } __empty;
int b[];
};
};
```
But this does:
```
union three {
int a;
int b[];
};
```
Remove the default error diagnostics for this but continue to provide
warnings under Microsoft or GNU extensions checks. This will allow for
a seamless transition for code bases away from 0-sized arrays without
losing existing code patterns. Add explicit checking for the warnings
under various constructions.
Additionally fixes a CodeGen bug with flexible array members in unions
in C++, which was found when adding a testcase for:
```
union { char x[]; } z = {0};
```
which only had Sema tests originally.
Fixes#84565
It is currently not possible to use "RVV type" and "RVV intrinsics" if
the "zve32x" is not enabled globally. However in some cases we may want
to use them only in some functions, for instance:
```
#include <riscv_vector.h>
__attribute__((target("+zve32x")))
vint32m1_t rvv_add(vint32m1_t v1, vint32m1_t v2, size_t vl) {
return __riscv_vadd(v1, v2, vl);
}
int other_add(int i1, int i2) {
return i1 + i2;
}
```
, it is supposed to be compilable even the vector is not specified, e.g.
`clang -target riscv64 -march=rv64gc -S test.c`.
In PR #79382, I need to add a new type that derives from
ConstantArrayType. This means that ConstantArrayType can no longer use
`llvm::TrailingObjects` to store the trailing optional Expr*.
This change refactors ConstantArrayType to store a 60-bit integer and
4-bits for the integer size in bytes. This replaces the APInt field
previously in the type but preserves enough information to recreate it
where needed.
To reduce the number of places where the APInt is re-constructed I've
also added some helper methods to the ConstantArrayType to allow some
common use cases that operate on either the stored small integer or the
APInt as appropriate.
Resolves#85124.
The latest ACLE allows it and further clarifies the following
in regards to the combination of the two attributes:
"If the `default` matches with another explicitly provided
version in the same translation unit, then the compiler can
emit only one function instead of the two. The explicitly
provided version shall be preferred."
("default" refers to the default clone here)
https://github.com/ARM-software/acle/pull/310
This was a limitation which has now been lifted. Please read the
thread below for more details:
https://github.com/llvm/llvm-project/pull/84405#discussion_r1525583647
Basically it allows to separate versioned implementations across
different TUs without having to share private header files which
contain the default declaration.
The ACLE spec has been updated accordingly to make this explicit:
"Each version declaration should be visible at the translation
unit in which the corresponding function version resides."
https://github.com/ARM-software/acle/pull/310
If a resolver is required (because there is a caller in the TU),
then a default declaration is implicitly generated.
In `-fbounds-safety`, bounds annotations are considered type attributes
rather than declaration attributes. Constructing them as type attributes
allows us to extend the attribute to apply nested pointers, which is
essential to annotate functions that involve out parameters: `void
foo(int *__counted_by(*out_count) *out_buf, int *out_count)`.
We introduce a new sugar type to support bounds annotated types,
`CountAttributedType`. In order to maintain extra data (the bounds
expression and the dependent declaration information) that is not
trackable in `AttributedType` we create a new type dedicate to this
functionality.
This patch also extends the parsing logic to parse the `counted_by`
argument as an expression, which will allow us to extend the model to
support arguments beyond an identifier, e.g., `__counted_by(n + m)` in
the future as specified by `-fbounds-safety`.
This also adjusts `__bdos` and array-bounds sanitizer code that already
uses `CountedByAttr` to check `CountAttributedType` instead to get the
field referred to by the attribute.
This reverts commit 92a09c0165b87032e1bd05020a78ed845cf35661.
This is triggering a bunch of new -Wnullability-completeness warnings
in code with existing raw pointer nullability annotations.
The intent was the new nullability locations wouldn't affect those
warnings, so this is a bug at least for now.
This enables clang and external nullability checkers to make use of
these annotations on nullable C++ class types like unique_ptr.
These types are recognized by the presence of the _Nullable attribute.
Nullable standard library types implicitly receive this attribute.
Existing static warnings for raw pointers are extended to smart
pointers:
- nullptr used as return value or argument for non-null functions
(`-Wnonnull`)
- assigning or initializing nonnull variables with nullable values
(`-Wnullable-to-nonnull-conversion`)
It doesn't implicitly add these attributes based on the assume_nonnull
pragma, nor warn on missing attributes where the pragma would apply
them.
I'm not confident that the pragma's current behavior will work well for
C++ (where type-based metaprogramming is much more common than C/ObjC).
We'd like to revisit this once we have more implementation experience.
Support can be detected as `__has_feature(nullability_on_classes)`.
This is needed for back-compatibility, as previously clang would issue a
hard error when _Nullable appears on a smart pointer.
UBSan's `-fsanitize=nullability` will not check smart-pointer types.
It can be made to do so by synthesizing calls to `operator bool`, but
that's left for future work.
Discussion:
https://discourse.llvm.org/t/rfc-allowing-nonnull-etc-on-smart-pointers/77201/26
The `ConceptReference`'s `FoundDecl` claims it "can differ from
`NamedConcept` when, for example, the concept was found through a
`UsingShadowDecl`", but such the contract was not previously respected.
Fixes https://github.com/llvm/llvm-project/issues/82628
Make TopLevelStmtDecl a DeclContext so that variables defined in statements
are attached to the TopLevelDeclContext. This fixes redefinition errors
from variables declared in if conditions and for-init statements. These
must be local to the inner context (C++ 3.3.2p4), but they had generated
definitions on global scope instead.
This PR makes the TopLevelStmtDecl looking more like a FunctionDecl and
that's fine because the FunctionDecl is very close in terms of semantics.
Additionally, ActOnForStmt() requires a CompoundScope when processing a
NullStmt body.
---------
Co-authored-by: Vassil Vassilev <v.g.vassilev@gmail.com>
The implementation mostly reuses C++ code paths where possible,
including narrowing check in order to provide diagnostic messages in
case initializer for constexpr variable is not exactly representable in
target type.
The following won't work due to lack of support for other features:
- Diagnosing of underspecified declarations involving constexpr
- Constexpr attached to compound literals
Also due to lack of support for char8_t some of examples with utf-8
strings don't work properly.
Fixes https://github.com/llvm/llvm-project/issues/64742
The following snippet causes a crash:
```
template<typename T>
struct A : T {
using T::f;
void f();
void g() {
f<int>(); // crash here
}
};
```
This happens because we cast the result of `getAsTemplateNameDecl` as a
`TemplateDecl` in `Sema::ClassifyName`, which we cannot do for an
`UnresolvedUsingValueDecl`. This patch fixes the crash by considering a name
to be that of a template if _any_ function declaration is found per [temp.names] p3.3.
Reapplies #78274 with the addition of a default-error warning
(`strict-primary-template-shadow`) that is issued for instances of
shadowing which were previously accepted prior to this patch.
I couldn't find an established convention for naming diagnostics related
to compatibility with previous versions of clang, so I just used the
prefix `ext_compat_`.
Copy constructors can have initialization with side effects, and thus
clang should not emit a warning when -Wunused-variable is used in this
context. Currently however, a warning is emitted.
Now, compilation happens without warnings.
Fixes#79518
According to [expr.prim.id.qual] p3:
> The _nested-name-specifier_ `::` nominates the global namespace. A
_nested-name-specifier_ with a _computed-type-specifier_ nominates the
type denoted by the _computed-type-specifier_, which shall be a class or
enumeration type. **If a _nested-name-specifier_ `N` is declarative and
has a _simple-template-id_ with a template argument list `A` that
involves a template parameter, let `T` be the template nominated by `N`
without `A`. `T` shall be a class template.**
Meaning, the out-of-line definition of `A::f` in the following example
is ill-formed:
```
template<typename T>
struct A
{
void f();
};
template<typename T>
using B = A<T>;
template<typename T>
void B<T>::f() { } // error: a declarative nested name specifier cannot name an alias template
```
This patch diagnoses such cases as an extension (in group `alias-template-in-declaration-name`).
C23 added the wb and uwb suffixes to generate a bit-precise integer
value. These values can be larger than what is representable in intmax_t
or uintmax_t.
We were asserting that an enumerator constant could not have a value
larger than unsigned long long but that's now a possibility. This patch
turns the assertion into a "value too large" diagnostic.
Note, we do not yet implement WG14 N3029 and so the behavior of this
patch will cause the enumerator to be cast to unsigned long long, but
this behavior may change in the future. GCC selects __uint128_t as the
underlying type for such an enumeration and we may want to match that
behavior in the future. This patch has several FIXME comments related to
this and the release notes call out the possibility of a change in
behavior in the future.
Fixes https://github.com/llvm/llvm-project/issues/69352
Without the fix gcc warns like
../../clang/lib/Sema/SemaDecl.cpp:2963:24: warning: unused variable 'SupA' [-Wunused-variable]
2963 | else if (const auto *SupA = dyn_cast<SuppressAttr>(Attr))
| ^~~~
and
../../clang/lib/Driver/Driver.cpp:4192:17: warning: unused variable 'IAA' [-Wunused-variable]
4192 | if (auto *IAA = dyn_cast<InstallAPIJobAction>(Current)) {
| ^~~
Remove the unused variables and change the "dyn_cast"s into "isa"s.
This patch expands notion of "interesting" in `IdentifierInto` it to
also cover ObjC keywords and builtins, which matches notion of
"interesting" in serialization layer. What was previously "interesting"
in `IdentifierInto` is now called "notable".
Beyond clearing confusion between serialization and the rest of the
compiler, it also resolved a naming problem: ObjC keywords, notable
identifiers, and builtin IDs are all stored in the same bit-field. Now
we can use "interesting" to name it and its corresponding type, instead
of `ObjCKeywordOrInterestingOrBuiltin` abomination.
The attribute is now allowed on an assortment of declarations, to
suppress warnings related to declarations themselves, or all warnings in
the lexical scope of the declaration.
I don't necessarily see a reason to have a list at all, but it does look
as if some of those more niche items aren't properly supported by the
compiler itself so let's maintain a short safe list for now.
The initial implementation raised a question whether the attribute
should apply to lexical declaration context vs. "actual" declaration
context. I'm using "lexical" here because it results in less warnings
suppressed, which is the conservative behavior: we can always expand it
later if we think this is wrong, without breaking any existing code. I
also think that this is the correct behavior that we will probably never
want to change, given that the user typically desires to keep the
suppressions as localized as possible.
According to [dcl.type.elab] p4:
> If an _elaborated-type-specifier_ appears with the `friend` specifier
as an entire _member-declaration_, the _member-declaration_ shall have
one of the following forms:
> `friend` _class-key_ _nested-name-specifier_(opt) _identifier_ `;`
> `friend` _class-key_ _simple-template-id_ `;`
> `friend` _class-key_ _nested-name-specifier_ `template`(opt)
_simple-template-id_ `;`
Notably absent from this list is the `enum` form of an
_elaborated-type-specifier_ "`enum` _nested-name-specifier_(opt)
_identifier_", which appears to be intentional per the resolution of
CWG2363.
Most major implementations accept these declarations, so the diagnostic
is a pedantic warning across all C++ versions.
In addition to the trivial cases previously diagnosed in C++98, we now
diagnose cases where the _elaborated-type-specifier_ has a dependent
_nested-name-specifier_:
```
template<typename T>
struct A
{
enum class E;
};
struct B
{
template<typename T>
friend enum A<T>::E; // pedantic warning: elaborated enumeration type cannot be a friend
};
template<typename T>
struct C
{
friend enum T::E; // pedantic warning: elaborated enumeration type cannot be a friend
};
```
This patch converts `Sema::TemplateDeductionResult` into a scoped enum
in namespace scope, making it eligible for forward declaring. This is
useful in certain contexts, such as `preferred_type` annotations on
bit-fields.
According to [dcl.fct] p23:
> An abbreviated function template can have a _template-head_. The
invented _template-parameters_ are appended to the
_template-parameter-list_ after the explicitly declared
_template-parameters_.
`template<>` is not a _template-head_ -- a _template-head_ must have at
least one _template-parameter_. This patch corrects our current behavior
of appending the invented template parameters to the innermost template
parameter list, regardless of whether it is empty. Example:
```
template<typename T>
struct A
{
void f(auto);
};
template<>
void A<int>::f(auto); // ok
template<>
template<> // warning: extraneous template parameter list in template specialization
void A<int>::f(auto);
```
Per the approved resolution for CWG2847, [temp.expl.spec] p8 will state:
> An explicit specialization shall not have a trailing _requires-clause_ unless it declares a function template.
We already implement this _partially_ insofar that a diagnostic is issued upon instantiation of `A<int>` in the following example:
```
template<typename>
struct A
{
template<typename>
void f();
template<>
void f<int>() requires true; // error: non-templated function cannot have a requires clause
};
template struct A<int>; // note: in instantiation of template class 'A<int>' requested here
```
This patch adds a bespoke diagnostic for such declarations, and moves the point of diagnosis for non-templated functions with trailing requires-clauses from `CheckFunctionDeclaration` to `ActOnFunctionDeclarator` (there is no point in diagnosing this during instantiation since we already have all the necessary information when parsing the declaration).
According to [temp.names] p5:
> The keyword template shall not appear immediately after a declarative nested-name-specifier.
[expr.prim.id.qual] p2 defines a declarative nested-name-specifier as follows:
> A nested-name-specifier is declarative if it is part of
> - a class-head-name,
> - an enum-head-name,
> - a qualified-id that is the id-expression of a declarator-id, or
> - a declarative nested-name-specifier.
Note: I believe this definition is defective as it doesn't include _nested-name-specifiers_ appearing in _elaborated-type-specifiers_ that declare partial/explicit specializations and explicit instantiations. See my post to the core reflector. Minus a few bugs that are addressed by this PR, this is how we implement it.
This means that declarations like:
```
template<typename>
struct A
{
template<typename>
struct B
{
void f();
};
};
template<typename T>
template<typename U>
void A<T>::template B<U>::f() { } // error: 'template' cannot be used after a declarative nested name specifier
```
are ill-formed. This PR add diagnostics for such declarations. The name of the diagnostic group is `template-in-declaration-name`.
Regarding the aforementioned "few bugs that are addressed by this PR" in order to correctly implement this:
- `CheckClassTemplate` did not call `diagnoseQualifiedDeclaration` when the semantic context was dependent. This allowed for constructs like:
```
struct A
{
template<typename T>
struct B
{
template<typename U>
struct C;
};
};
template<typename T>
template<typename U>
struct decltype(A())::B<T>::C { };
```
- `ActOnClassTemplateSpecialization` did not call `diagnoseQualifiedDeclaration` at all, allowing for qualified partial/explicit specializations at class scope and other related nonsense
- `TreeTransform::TransformNestedNameSpecifierLoc` would rebuild a `NestedNameSpecifier::TypeSpecWithTemplate` as a `NestedNameSpecifier::TypeSpec`
- `TemplateSpecializationTypeLoc::initializeLocal` would set the `template` keyword `SourceLocation` to the provided `Loc` parameter, which would result in a `TemplateSpecializationTypeLoc` obtained via `ASTContext::getTrivialTypeSourceInfo` being displayed as always having a `template` prefix (since the presence of the keyword is not stored anywhere else).
Consider the following:
```
namespace N0 {
namespace N1 {
template<typename T>
int x1 = 0;
}
using namespace N1;
}
template<>
int N0::x1<int>;
```
According to [dcl.meaning.general] p3.3:
> - If the _declarator_ declares an explicit instantiation or a partial
or explicit specialization, the _declarator_ does not bind a name. If it
declares a class member, the terminal name of the _declarator-id_ is not
looked up; otherwise, **only those lookup results that are nominable in
`S` are considered when identifying any function template specialization
being declared**.
In particular, the requirement for lookup results to be nominal in the
lookup context of the terminal name of the _declarator-id_ only applies
to function template specializations -- not variable template
specializations. We currently reject the above declaration, but we do
(correctly) accept it if the using-directive is replaced with a `using`
declaration naming `N0::N1::x1`. This patch makes it so the above
specialization is (correctly) accepted.
- Sema::isSimpleTypeSpecifier return true for _Bool in c99 (currently
returns false for _Bool, regardless of C dialect). (Fixes#72203)
- replace the logic with a check for simple types and a proper check for
a valid keyword in the appropriate dialect
Co-authored-by: Carl Peto <CPeto@becrypt.com>
According to [[dcl.type.elab]
p2](http://eel.is/c++draft/dcl.type.elab#2):
> If an
[elaborated-type-specifier](http://eel.is/c++draft/dcl.type.elab#nt:elaborated-type-specifier)
is the sole constituent of a declaration, the declaration is ill-formed
unless it is an explicit specialization, an explicit instantiation or it
has one of the following forms [...]
Consider the following:
```cpp
template<typename T>
struct A
{
template<typename U>
struct B;
};
template<>
template<typename U>
struct A<int>::B; // #1
```
The _elaborated-type-specifier_ at `#1` declares an explicit
specialization (which is itself a template). We currently (incorrectly)
reject this, and this PR fixes that.
I moved the point at which _elaborated-type-specifiers_ with
_nested-name-specifiers_ are diagnosed from `ParsedFreeStandingDeclSpec`
to `ActOnTag` for two reasons: `ActOnTag` isn't called for explicit
instantiations and partial/explicit specializations, and because it's
where we determine if a member specialization is being declared.
With respect to diagnostics, I am currently issuing the diagnostic
without marking the declaration as invalid or returning early, which
results in more diagnostics that I think is necessary. I would like
feedback regarding what the "correct" behavior should be here.
`OpaqueValueExpr` doesn't necessarily contain a source expression.
Particularly, after #78041, it is used to carry the type and the value
kind of a non-type template argument of floating-point type or referring
to a subobject (those are so called `StructuralValue` arguments).
This fixes#79575.
Implements https://isocpp.org/files/papers/P2662R3.pdf
The feature is exposed as an extension in older language modes.
Mangling is not yet supported and that is something we will have to do before release.
