[Clang] Fix __has_cpp_attribute and C++11 attributes with arguments in C++03 (#83065)

The values for `__has_cpp_attribute` don't have to be guarded behind
`LangOpts.CPlusPlus` because `__has_cpp_at

[Clang] Fix __has_cpp_attribute and C++11 attributes with arguments in C++03 (#83065)

The values for `__has_cpp_attribute` don't have to be guarded behind
`LangOpts.CPlusPlus` because `__has_cpp_attribute` isn't available if
Clang isn't in a C++ mode.

Fixes #82995

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[clang] Fix several issues in the generated AttrHasAttributeImpl.inc

1. The generated file contained a lot of duplicate switch cases, e.g.:
```
switch (Syntax) {
case AttributeCommonInfo::Syntax::AS

[clang] Fix several issues in the generated AttrHasAttributeImpl.inc

1. The generated file contained a lot of duplicate switch cases, e.g.:
```
switch (Syntax) {
case AttributeCommonInfo::Syntax::AS_GNU:
return llvm::StringSwitch<int>(Name)
...
.Case("error", 1)
.Case("warning", 1)
.Case("error", 1)
.Case("warning", 1)
```

2. Some attributes were listed in wrong places, e.g.:
```
case AttributeCommonInfo::Syntax::AS_CXX11: {
if (ScopeName == "") {
return llvm::StringSwitch<int>(Name)
...
.Case("warn_unused_result", LangOpts.CPlusPlus11 ? 201907 : 0)
```

`warn_unused_result` is a non-standard attribute and should not be
available as [[warn_unused_result]].

3. Some attributes had the wrong version, e.g.:
```
case AttributeCommonInfo::Syntax::AS_CXX11: {
} else if (ScopeName == "gnu") {
return llvm::StringSwitch<int>(Name)
...
.Case("fallthrough", LangOpts.CPlusPlus11 ? 201603 : 0)
```

[[gnu::fallthrough]] is a non-standard spelling and should not have the
standard version. Instead, __has_cpp_attribute should return 1 for it.

There is another issue with attributes that share spellings, e.g.:
```
.Case("interrupt", true && (T.getArch() == llvm::Triple::arm || ...) ? 1 : 0)
.Case("interrupt", true && (T.getArch() == llvm::Triple::avr) ? 1 : 0)
...
.Case("interrupt", true && (T.getArch() == llvm::Triple::riscv32 || ...) ? 1 : 0)
```
As can be seen, __has_attribute(interrupt) would only return true for
ARM targets. This patch does not address this issue.

Differential Revision: https://reviews.llvm.org/D159393

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Recommit "Implement [[msvc::no_unique_address]] (#65675)" (#67199)

This implements the [[msvc::no_unique_address]] attribute.

There is not ABI compatibility in this patch because the attribute is

Recommit "Implement [[msvc::no_unique_address]] (#65675)" (#67199)

This implements the [[msvc::no_unique_address]] attribute.

There is not ABI compatibility in this patch because the attribute is
relatively new and there's still some uncertainty in the MSVC version.

The recommit changes the attribute definitions so that instead of making
two separate attributes for no_unique_address
and msvc::no_unique_address, it modifies the attributes tablegen emitter
to allow spellings to be target-specific.

This reverts commit 71f9e7695b87298f9855d8890f0e6a3b89381eb5.

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Revert "Implement [[msvc::no_unique_address]] (#65675)" (#67198)

This reverts commit 4a55d426967b9c70f5dea7b3a389e11393a4f4c4.

Reverting because this breaks sphinx documentation, and even with it

Revert "Implement [[msvc::no_unique_address]] (#65675)" (#67198)

This reverts commit 4a55d426967b9c70f5dea7b3a389e11393a4f4c4.

Reverting because this breaks sphinx documentation, and even with it
fixed the format of the attribute makes the no_unique_address
documentation show up twice.

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Implement [[msvc::no_unique_address]] (#65675)

This implements the [[msvc::no_unique_address]] attribute.

There is not ABI compatibility in this patch because the attribute is
relatively new and

Implement [[msvc::no_unique_address]] (#65675)

This implements the [[msvc::no_unique_address]] attribute.

There is not ABI compatibility in this patch because the attribute is
relatively new and there's still some uncertainty in the MSVC version.

Bug: https://github.com/llvm/llvm-project/issues/49358

Also see https://reviews.llvm.org/D157762.

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Lex arguments for __has_cpp_attribute and friends as expanded tokens

The C and C++ standards require the argument to __has_cpp_attribute and
__has_c_attribute to be expanded ([cpp.cond]p5). It would

Lex arguments for __has_cpp_attribute and friends as expanded tokens

The C and C++ standards require the argument to __has_cpp_attribute and
__has_c_attribute to be expanded ([cpp.cond]p5). It would make little sense
to expand the argument to those operators but not expand the argument to
__has_attribute and __has_declspec, so those were both also changed in this
patch.

Note that it might make sense for the other builtins to also expand their
argument, but it wasn't as clear to me whether the behavior would be correct
there, and so they were left for a future revision.

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[Sema, CodeGen] Implement [[likely]] and [[unlikely]] in SwitchStmt

This implements the likelihood attribute for the switch statement. Based on the
discussion in D85091 and D86559 it only handles th

[Sema, CodeGen] Implement [[likely]] and [[unlikely]] in SwitchStmt

This implements the likelihood attribute for the switch statement. Based on the
discussion in D85091 and D86559 it only handles the attribute when placed on
the case labels or the default labels.

It also marks the likelihood attribute as feature complete. There are more QoI
patches in the pipeline.

Differential Revision: https://reviews.llvm.org/D89210

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Implements [[likely]] and [[unlikely]] in IfStmt.

This is the initial part of the implementation of the C++20 likelihood
attributes. It handles the attributes in an if statement.

Differential Revis

Implements [[likely]] and [[unlikely]] in IfStmt.

This is the initial part of the implementation of the C++20 likelihood
attributes. It handles the attributes in an if statement.

Differential Revision: https://reviews.llvm.org/D85091

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Allow standards-based attributes to have leading and trailing underscores.

This gives library implementers a way to use standards-based attributes that do not conflict with user-defined macros of th

Allow standards-based attributes to have leading and trailing underscores.

This gives library implementers a way to use standards-based attributes that do not conflict with user-defined macros of the same name. Attributes in C2x require this behavior normatively (C2x 6.7.11p4), but there's no reason to not have the same behavior in C++, especially given that such attributes may be used by a C library consumed by a C++ compilation.

llvm-svn: 369033

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Implement P1771

As passed in the Cologne meeting and treated by Core as a DR,
[[nodiscard]] was applied to constructors so that they can be diagnosed
in cases where the user forgets a variable name

Implement P1771

As passed in the Cologne meeting and treated by Core as a DR,
[[nodiscard]] was applied to constructors so that they can be diagnosed
in cases where the user forgets a variable name for a type.

The intent is to enable the library to start using this on the
constructors of scope_guard/lock_guard.

Differential Revision: https://reviews.llvm.org/D64914

llvm-svn: 367027

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Revert the change to the [[nodiscard]] feature test macro value.

This value only gets bumped once both P1301 and P1771 are implemented.

llvm-svn: 366682

Implement P1301R4, which allows specifying an optional message on the [[nodiscard]] attribute.

This also bumps the attribute feature test value and introduces the notion of a C++2a extension warning

Implement P1301R4, which allows specifying an optional message on the [[nodiscard]] attribute.

This also bumps the attribute feature test value and introduces the notion of a C++2a extension warning.

llvm-svn: 366626

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Fix has_attribute.cpp test on Windows after r364102

llvm-svn: 364108

Fix __has_cpp_attribute expansion to produce trailing L and (where
necessary) leading whitespace.

Simplify unit test and extend to cover no_unique_address attribute.

llvm-svn: 364102

Introduce the _Clang scoped attribute token.

Currently, we only accept clang as the scoped attribute identifier for double square bracket attributes provided by Clang, but this has the potential to

Introduce the _Clang scoped attribute token.

Currently, we only accept clang as the scoped attribute identifier for double square bracket attributes provided by Clang, but this has the potential to conflict with user-defined macros. To help alleviate these concerns, this introduces the _Clang scoped attribute identifier as an alias for clang. It also introduces a warning with a fixit on the off chance someone attempts to use __clang__ as the scoped attribute (which is a predefined compiler identification macro).

llvm-svn: 346521

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Support accepting __gnu__ as a scoped attribute namespace that aliases to gnu.

This is useful in libstdc++ to avoid clashes with identifiers in the user's namespace.

llvm-svn: 345132

Define __has_cpp_attribute(fallthrough) to a more reasonable value. (What year is it?!)

llvm-svn: 262887

Added a new preprocessor macro: __has_declspec_attribute. This can be used as a way to determine whether Clang supports a __declspec spelling for a given attribute, similar to __has_attribute and __

Added a new preprocessor macro: __has_declspec_attribute. This can be used as a way to determine whether Clang supports a __declspec spelling for a given attribute, similar to __has_attribute and __has_cpp_attribute.

llvm-svn: 223467

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Convert CR+LF -> LF in a test file

llvm-svn: 222429

Avoid earlier test interfering with later one.

llvm-svn: 222403

Complete support for the SD-6 standing document (based off N4200) with support for __has_cpp_attribute.

llvm-svn: 221991