[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

In D151683#4566907 , @eaeltsin wrote:

> Hi,
>
> Is it a known issue, that clang doesn't compile `void foo(char *argv[] 
> [[maybe_unused]]) {}` ? The error is `error: 'maybe_unused' attribute cannot 
> be applied to types`.
>
> https://godbolt.org/z/r9E81cWxh - clang fails, but gcc doesn't.
>
> It looks like there is a lot of oss code of the form `void foo(char *argv[] 
> ATTRIBUTE_UNUSED)`, where `ATTRIBUTE_UNUSED` was configured to 
> `__attribute__((unused))` before this change (thus compiled ok) and to 
> `[[maybe_unused]]` after this change (thus started to break).

https://eel.is/c++draft/dcl.array#3.sentence-2 -- an attribute in that position 
appertains to the array type and `maybe_unused` cannot be applied to types in 
that way, so I believe Clang's behavior is correct. So I think the C++ 
attribute behavior is expected, but the change between `__attribute__` and 
`[[]]` may be catching folks off-guard.


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Evgeny Eltsin via Phabricator via cfe-commits]

eaeltsin added a comment.

Hi,

Is it a known issue, that clang doesn't compile `void foo(char *argv[] 
[[maybe_unused]]) {}` ?

https://godbolt.org/z/r9E81cWxh - clang fails, but gcc doesn't.

It looks like there is a lot of oss code of the form `void foo(char *argv[] 
ATTRIBUTE_UNUSED)`, where `ATTRIBUTE_UNUSED` was configured to 
`__attribute__((unused))` before this change (thus compiled ok) and to 
`[[maybe_unused]]` after this change (thus started to break).


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG874217f99b99: [clang] Enable C++11-style attributes in all 
language modes (authored by philnik).

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Files:
  clang/docs/LanguageExtensions.rst
  clang/docs/ReleaseNotes.rst
  clang/include/clang/Basic/DiagnosticParseKinds.td
  clang/include/clang/Basic/Features.def
  clang/include/clang/Driver/Options.td
  clang/include/clang/Parse/Parser.h
  clang/lib/Basic/Attributes.cpp
  clang/lib/Lex/Lexer.cpp
  clang/lib/Parse/ParseDeclCXX.cpp
  clang/test/AST/ast-dump-attr.m
  clang/test/AST/ast-dump-c-attr.c
  clang/test/AST/attr-annotate-type.c
  clang/test/CodeGen/attr-btf_type_tag-func.c
  clang/test/CodeGen/attr-btf_type_tag-var.c
  clang/test/Frontend/noderef.c
  clang/test/OpenMP/assumes_messages_attr.c
  clang/test/OpenMP/openmp_attribute_compat.cpp
  clang/test/Parser/asm.c
  clang/test/Parser/c2x-attributes.c
  clang/test/Parser/c2x-attributes.m
  clang/test/Parser/cxx-decl.cpp
  clang/test/Parser/objc-attr.m
  clang/test/ParserHLSL/group_shared.hlsl
  clang/test/Preprocessor/has_c_attribute.c
  clang/test/Sema/annotate-type.c
  clang/test/Sema/annotate.c
  clang/test/Sema/attr-availability-square-brackets.c
  clang/test/Sema/attr-external-source-symbol-cxx.cpp
  clang/test/Sema/attr-external-source-symbol.c
  clang/test/Sema/attr-likelihood.c
  clang/test/Sema/attr-objc-bridge-related.m
  clang/test/Sema/attr-regparm.c
  clang/test/Sema/attr-type-safety.c
  clang/test/Sema/c2x-attr.c
  clang/test/Sema/c2x-noreturn.c
  clang/test/Sema/internal_linkage.c
  clang/test/Sema/matrix-type-builtins.c
  clang/test/Sema/neon-vector-types.c
  clang/test/Sema/overload-arm-mve.c
  clang/test/Sema/overloadable.c
  clang/test/Sema/vector-gcc-compat.c
  clang/test/SemaCXX/attr-cxx-disabled.cpp
  clang/test/SemaCXX/cxx98-compat.cpp
  clang/test/SemaCXX/warn-c++11-extensions.cpp
  clang/test/SemaObjC/attr-objc-gc.m
  clang/unittests/AST/AttrTest.cpp
  clang/utils/TableGen/ClangAttrEmitter.cpp
  lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
===
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -575,7 +575,6 @@
 // FIXME: We should ask the driver for the appropriate default flags.
 lang_opts.GNUMode = true;
 lang_opts.GNUKeywords = true;
-lang_opts.DoubleSquareBracketAttributes = true;
 lang_opts.CPlusPlus11 = true;
 
 // The Darwin libc expects this macro to be set.
Index: clang/utils/TableGen/ClangAttrEmitter.cpp
===
--- clang/utils/TableGen/ClangAttrEmitter.cpp
+++ clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3394,14 +3394,10 @@
   // If this is the C++11 variety, also add in the LangOpts test.
   if (Variety == "CXX11")
 Test += " && LangOpts.CPlusPlus11";
-  else if (Variety == "C2x")
-Test += " && LangOpts.DoubleSquareBracketAttributes";
 } else if (Variety == "CXX11")
   // C++11 mode should be checked against LangOpts, which is presumed to be
   // present in the caller.
   Test = "LangOpts.CPlusPlus11";
-else if (Variety == "C2x")
-  Test = "LangOpts.DoubleSquareBracketAttributes";
 
 std::string TestStr = !Test.empty()
   ? Test + " ? " + llvm::itostr(Version) + " : 0"
Index: clang/unittests/AST/AttrTest.cpp
===
--- clang/unittests/AST/AttrTest.cpp
+++ clang/unittests/AST/AttrTest.cpp
@@ -157,7 +157,7 @@
   AST = buildASTFromCodeWithArgs(R"c(
 __auto_type [[clang::annotate_type("auto")]] auto_var = 1;
   )c",
- {"-fdouble-square-bracket-attributes"},
+ {},
  "input.c");
 
   {
Index: clang/test/SemaObjC/attr-objc-gc.m
===
--- clang/test/SemaObjC/attr-objc-gc.m
+++ clang/test/SemaObjC/attr-objc-gc.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -fdouble-square-bracket-attributes -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify %s
 static id __attribute((objc_gc(weak))) a;
 static id __attribute((objc_gc(strong))) b;
 
Index: clang/test/SemaCXX/warn-c++11-extensions.cpp
===
--- clang/test/SemaCXX/warn-c++11-extensions.cpp
+++ clang/test/SemaCXX/warn-c++11-extensions.cpp
@@ -7,3 +7,5 @@
 
 enum struct E1 { A, B }; // expected-warning {{scoped 

[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman accepted this revision.
aaron.ballman added a comment.

LGTM!


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik updated this revision to Diff 542743.
philnik added a comment.

- Address comments
- Try to fix CI
- Rebased


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Files:
  clang/docs/LanguageExtensions.rst
  clang/docs/ReleaseNotes.rst
  clang/include/clang/Basic/DiagnosticParseKinds.td
  clang/include/clang/Basic/Features.def
  clang/include/clang/Driver/Options.td
  clang/include/clang/Parse/Parser.h
  clang/lib/Basic/Attributes.cpp
  clang/lib/Lex/Lexer.cpp
  clang/lib/Parse/ParseDeclCXX.cpp
  clang/test/AST/ast-dump-attr.m
  clang/test/AST/ast-dump-c-attr.c
  clang/test/AST/attr-annotate-type.c
  clang/test/CodeGen/attr-btf_type_tag-func.c
  clang/test/CodeGen/attr-btf_type_tag-var.c
  clang/test/Frontend/noderef.c
  clang/test/OpenMP/assumes_messages_attr.c
  clang/test/OpenMP/openmp_attribute_compat.cpp
  clang/test/Parser/asm.c
  clang/test/Parser/c2x-attributes.c
  clang/test/Parser/c2x-attributes.m
  clang/test/Parser/cxx-decl.cpp
  clang/test/Parser/objc-attr.m
  clang/test/ParserHLSL/group_shared.hlsl
  clang/test/Preprocessor/has_c_attribute.c
  clang/test/Sema/annotate-type.c
  clang/test/Sema/annotate.c
  clang/test/Sema/attr-availability-square-brackets.c
  clang/test/Sema/attr-external-source-symbol-cxx.cpp
  clang/test/Sema/attr-external-source-symbol.c
  clang/test/Sema/attr-likelihood.c
  clang/test/Sema/attr-objc-bridge-related.m
  clang/test/Sema/attr-regparm.c
  clang/test/Sema/attr-type-safety.c
  clang/test/Sema/c2x-attr.c
  clang/test/Sema/c2x-noreturn.c
  clang/test/Sema/internal_linkage.c
  clang/test/Sema/matrix-type-builtins.c
  clang/test/Sema/neon-vector-types.c
  clang/test/Sema/overload-arm-mve.c
  clang/test/Sema/overloadable.c
  clang/test/Sema/vector-gcc-compat.c
  clang/test/SemaCXX/attr-cxx-disabled.cpp
  clang/test/SemaCXX/cxx98-compat.cpp
  clang/test/SemaCXX/warn-c++11-extensions.cpp
  clang/test/SemaObjC/attr-objc-gc.m
  clang/unittests/AST/AttrTest.cpp
  clang/utils/TableGen/ClangAttrEmitter.cpp
  lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
===
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -575,7 +575,6 @@
 // FIXME: We should ask the driver for the appropriate default flags.
 lang_opts.GNUMode = true;
 lang_opts.GNUKeywords = true;
-lang_opts.DoubleSquareBracketAttributes = true;
 lang_opts.CPlusPlus11 = true;
 
 // The Darwin libc expects this macro to be set.
Index: clang/utils/TableGen/ClangAttrEmitter.cpp
===
--- clang/utils/TableGen/ClangAttrEmitter.cpp
+++ clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3394,14 +3394,10 @@
   // If this is the C++11 variety, also add in the LangOpts test.
   if (Variety == "CXX11")
 Test += " && LangOpts.CPlusPlus11";
-  else if (Variety == "C2x")
-Test += " && LangOpts.DoubleSquareBracketAttributes";
 } else if (Variety == "CXX11")
   // C++11 mode should be checked against LangOpts, which is presumed to be
   // present in the caller.
   Test = "LangOpts.CPlusPlus11";
-else if (Variety == "C2x")
-  Test = "LangOpts.DoubleSquareBracketAttributes";
 
 std::string TestStr = !Test.empty()
   ? Test + " ? " + llvm::itostr(Version) + " : 0"
Index: clang/unittests/AST/AttrTest.cpp
===
--- clang/unittests/AST/AttrTest.cpp
+++ clang/unittests/AST/AttrTest.cpp
@@ -157,7 +157,7 @@
   AST = buildASTFromCodeWithArgs(R"c(
 __auto_type [[clang::annotate_type("auto")]] auto_var = 1;
   )c",
- {"-fdouble-square-bracket-attributes"},
+ {},
  "input.c");
 
   {
Index: clang/test/SemaObjC/attr-objc-gc.m
===
--- clang/test/SemaObjC/attr-objc-gc.m
+++ clang/test/SemaObjC/attr-objc-gc.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -fdouble-square-bracket-attributes -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify %s
 static id __attribute((objc_gc(weak))) a;
 static id __attribute((objc_gc(strong))) b;
 
Index: clang/test/SemaCXX/warn-c++11-extensions.cpp
===
--- clang/test/SemaCXX/warn-c++11-extensions.cpp
+++ clang/test/SemaCXX/warn-c++11-extensions.cpp
@@ -7,3 +7,5 @@
 
 enum struct E1 { A, B }; // expected-warning {{scoped enumerations are a C++11 extension}}
 enum class E2 { C, D }; // expected-warning {{scoped enumerations are a C++11 extension}}
+
+[[]] void 

[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik added a comment.

In D151683#4508209 , @MaskRay wrote:

> Reverse ping @philnik :)
>
> The `release/17.x` branch will be created soon 
> (https://discourse.llvm.org/t/llvm-17-0-0-release-planning-and-update/71762).

I know. I just didn't have the time yet. If you want to make sure it's in 17 
feel free to commandeer and fix the last bits.


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added a comment.

Reverse ping @philnik :)

The `release/17.x` branch will be created soon 
(https://discourse.llvm.org/t/llvm-17-0-0-release-planning-and-update/71762).


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added a comment.

In D151683#4486321 , @aaron.ballman 
wrote:

> Aside from the failing precommit CI test case in C, I think this LGTM. I've 
> added @MaskRay as the code owner for the command line option changes in case 
> he's got concerns regarding the deprecation/removal plans.



  - ``-fdouble-square-bracket-attributes`` has been deprecated. It is ignored 
now
and will be removed in CLang 18.

sounds good. (Minor case typo in `CLang`). As you said in

https://discourse.llvm.org/t/rfc-enable-c-11-c2x-attributes-in-all-standard-modes-as-an-extension-and-remove-fdouble-square-bracket-attributes/71268/2

> I’m in support of this idea. I think we should enable the extension 
> unconditionally for Clang 17 with a release note mentioning that 
> -fdouble-square-bracket-attributes will be removed in Clang 18 just as a 
> kindness to users with proprietary code bases that might be using it.

I think a clear summary/commit message should mention that this patch makes 
`[[...]]`` available to C++03 and C17 with no warning by default.

It's also worth calling out that GCC since 10 supports `[[]]` in all C language 
modes (AFAICT there is no warning even with `gcc -std=c89 -c a.c`) (there is a 
warning `-pedantic`).

  % g++ -c a.cc -std=c++03
  a.cc:2:1: error: expected unqualified-id before ‘[’ token
  2 | [[nodiscard]] int without_underscores(void);
| ^
  % myclang++ -c a.cc -std=c++03  # no warning with this patch


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a reviewer: MaskRay.
aaron.ballman added a comment.

Aside from the failing precommit CI test case in C, I think this LGTM. I've 
added @MaskRay as the code owner for the command line option changes in case 
he's got concerns regarding the deprecation/removal plans.


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik updated this revision to Diff 536623.
philnik edited the summary of this revision.
philnik added a comment.

Try to fix CI


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Files:
  clang/docs/LanguageExtensions.rst
  clang/docs/ReleaseNotes.rst
  clang/include/clang/Basic/DiagnosticParseKinds.td
  clang/include/clang/Basic/Features.def
  clang/include/clang/Driver/Options.td
  clang/include/clang/Parse/Parser.h
  clang/lib/Basic/Attributes.cpp
  clang/lib/Lex/Lexer.cpp
  clang/lib/Parse/ParseDeclCXX.cpp
  clang/test/AST/ast-dump-attr.m
  clang/test/AST/ast-dump-c-attr.c
  clang/test/AST/attr-annotate-type.c
  clang/test/CodeGen/attr-btf_type_tag-func.c
  clang/test/CodeGen/attr-btf_type_tag-var.c
  clang/test/Frontend/noderef.c
  clang/test/OpenMP/assumes_messages_attr.c
  clang/test/OpenMP/openmp_attribute_compat.cpp
  clang/test/Parser/asm.c
  clang/test/Parser/c2x-attributes.c
  clang/test/Parser/c2x-attributes.m
  clang/test/Parser/cxx-decl.cpp
  clang/test/Parser/objc-attr.m
  clang/test/ParserHLSL/group_shared.hlsl
  clang/test/Preprocessor/has_c_attribute.c
  clang/test/Sema/annotate-type.c
  clang/test/Sema/annotate.c
  clang/test/Sema/attr-availability-square-brackets.c
  clang/test/Sema/attr-external-source-symbol-cxx.cpp
  clang/test/Sema/attr-external-source-symbol.c
  clang/test/Sema/attr-likelihood.c
  clang/test/Sema/attr-objc-bridge-related.m
  clang/test/Sema/attr-regparm.c
  clang/test/Sema/attr-type-safety.c
  clang/test/Sema/c2x-attr.c
  clang/test/Sema/c2x-noreturn.c
  clang/test/Sema/internal_linkage.c
  clang/test/Sema/matrix-type-builtins.c
  clang/test/Sema/neon-vector-types.c
  clang/test/Sema/overload-arm-mve.c
  clang/test/Sema/overloadable.c
  clang/test/Sema/vector-gcc-compat.c
  clang/test/SemaCXX/attr-cxx-disabled.cpp
  clang/test/SemaCXX/cxx98-compat.cpp
  clang/test/SemaCXX/warn-c++11-extensions.cpp
  clang/test/SemaObjC/attr-objc-gc.m
  clang/unittests/AST/AttrTest.cpp
  clang/utils/TableGen/ClangAttrEmitter.cpp
  lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
===
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -575,7 +575,6 @@
 // FIXME: We should ask the driver for the appropriate default flags.
 lang_opts.GNUMode = true;
 lang_opts.GNUKeywords = true;
-lang_opts.DoubleSquareBracketAttributes = true;
 lang_opts.CPlusPlus11 = true;
 
 // The Darwin libc expects this macro to be set.
Index: clang/utils/TableGen/ClangAttrEmitter.cpp
===
--- clang/utils/TableGen/ClangAttrEmitter.cpp
+++ clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3394,14 +3394,10 @@
   // If this is the C++11 variety, also add in the LangOpts test.
   if (Variety == "CXX11")
 Test += " && LangOpts.CPlusPlus11";
-  else if (Variety == "C2x")
-Test += " && LangOpts.DoubleSquareBracketAttributes";
 } else if (Variety == "CXX11")
   // C++11 mode should be checked against LangOpts, which is presumed to be
   // present in the caller.
   Test = "LangOpts.CPlusPlus11";
-else if (Variety == "C2x")
-  Test = "LangOpts.DoubleSquareBracketAttributes";
 
 std::string TestStr = !Test.empty()
   ? Test + " ? " + llvm::itostr(Version) + " : 0"
Index: clang/unittests/AST/AttrTest.cpp
===
--- clang/unittests/AST/AttrTest.cpp
+++ clang/unittests/AST/AttrTest.cpp
@@ -157,7 +157,7 @@
   AST = buildASTFromCodeWithArgs(R"c(
 __auto_type [[clang::annotate_type("auto")]] auto_var = 1;
   )c",
- {"-fdouble-square-bracket-attributes"},
+ {},
  "input.c");
 
   {
Index: clang/test/SemaObjC/attr-objc-gc.m
===
--- clang/test/SemaObjC/attr-objc-gc.m
+++ clang/test/SemaObjC/attr-objc-gc.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -fdouble-square-bracket-attributes -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify %s
 static id __attribute((objc_gc(weak))) a;
 static id __attribute((objc_gc(strong))) b;
 
Index: clang/test/SemaCXX/warn-c++11-extensions.cpp
===
--- clang/test/SemaCXX/warn-c++11-extensions.cpp
+++ clang/test/SemaCXX/warn-c++11-extensions.cpp
@@ -7,3 +7,5 @@
 
 enum struct E1 { A, B }; // expected-warning {{scoped enumerations are a C++11 extension}}
 enum class E2 { C, D }; // expected-warning {{scoped enumerations are a C++11 

[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik updated this revision to Diff 536620.
philnik marked 16 inline comments as done.
philnik added a comment.

Address comments


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Files:
  clang/docs/LanguageExtensions.rst
  clang/docs/ReleaseNotes.rst
  clang/include/clang/Basic/DiagnosticParseKinds.td
  clang/include/clang/Basic/Features.def
  clang/include/clang/Driver/Options.td
  clang/include/clang/Parse/Parser.h
  clang/lib/Basic/Attributes.cpp
  clang/lib/Lex/Lexer.cpp
  clang/lib/Parse/ParseDeclCXX.cpp
  clang/test/AST/ast-dump-attr.m
  clang/test/AST/ast-dump-c-attr.c
  clang/test/AST/attr-annotate-type.c
  clang/test/CodeGen/attr-btf_type_tag-func.c
  clang/test/CodeGen/attr-btf_type_tag-var.c
  clang/test/Frontend/noderef.c
  clang/test/OpenMP/assumes_messages_attr.c
  clang/test/OpenMP/openmp_attribute_compat.cpp
  clang/test/Parser/asm.c
  clang/test/Parser/c2x-attributes.c
  clang/test/Parser/c2x-attributes.m
  clang/test/Parser/cxx-decl.cpp
  clang/test/Parser/objc-attr.m
  clang/test/ParserHLSL/group_shared.hlsl
  clang/test/Preprocessor/has_c_attribute.c
  clang/test/Sema/annotate-type.c
  clang/test/Sema/annotate.c
  clang/test/Sema/attr-availability-square-brackets.c
  clang/test/Sema/attr-external-source-symbol-cxx.cpp
  clang/test/Sema/attr-external-source-symbol.c
  clang/test/Sema/attr-likelihood.c
  clang/test/Sema/attr-objc-bridge-related.m
  clang/test/Sema/attr-regparm.c
  clang/test/Sema/attr-type-safety.c
  clang/test/Sema/c2x-attr.c
  clang/test/Sema/c2x-noreturn.c
  clang/test/Sema/internal_linkage.c
  clang/test/Sema/matrix-type-builtins.c
  clang/test/Sema/neon-vector-types.c
  clang/test/Sema/overload-arm-mve.c
  clang/test/Sema/overloadable.c
  clang/test/Sema/vector-gcc-compat.c
  clang/test/SemaCXX/attr-cxx-disabled.cpp
  clang/test/SemaCXX/cxx98-compat.cpp
  clang/test/SemaCXX/warn-c++11-extensions.cpp
  clang/test/SemaObjC/attr-objc-gc.m
  clang/unittests/AST/AttrTest.cpp
  clang/utils/TableGen/ClangAttrEmitter.cpp
  lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
===
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -575,7 +575,6 @@
 // FIXME: We should ask the driver for the appropriate default flags.
 lang_opts.GNUMode = true;
 lang_opts.GNUKeywords = true;
-lang_opts.DoubleSquareBracketAttributes = true;
 lang_opts.CPlusPlus11 = true;
 
 // The Darwin libc expects this macro to be set.
Index: clang/utils/TableGen/ClangAttrEmitter.cpp
===
--- clang/utils/TableGen/ClangAttrEmitter.cpp
+++ clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3394,14 +3394,10 @@
   // If this is the C++11 variety, also add in the LangOpts test.
   if (Variety == "CXX11")
 Test += " && LangOpts.CPlusPlus11";
-  else if (Variety == "C2x")
-Test += " && LangOpts.DoubleSquareBracketAttributes";
 } else if (Variety == "CXX11")
   // C++11 mode should be checked against LangOpts, which is presumed to be
   // present in the caller.
   Test = "LangOpts.CPlusPlus11";
-else if (Variety == "C2x")
-  Test = "LangOpts.DoubleSquareBracketAttributes";
 
 std::string TestStr = !Test.empty()
   ? Test + " ? " + llvm::itostr(Version) + " : 0"
Index: clang/unittests/AST/AttrTest.cpp
===
--- clang/unittests/AST/AttrTest.cpp
+++ clang/unittests/AST/AttrTest.cpp
@@ -157,7 +157,7 @@
   AST = buildASTFromCodeWithArgs(R"c(
 __auto_type [[clang::annotate_type("auto")]] auto_var = 1;
   )c",
- {"-fdouble-square-bracket-attributes"},
+ {},
  "input.c");
 
   {
Index: clang/test/SemaObjC/attr-objc-gc.m
===
--- clang/test/SemaObjC/attr-objc-gc.m
+++ clang/test/SemaObjC/attr-objc-gc.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -fdouble-square-bracket-attributes -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify %s
 static id __attribute((objc_gc(weak))) a;
 static id __attribute((objc_gc(strong))) b;
 
Index: clang/test/SemaCXX/warn-c++11-extensions.cpp
===
--- clang/test/SemaCXX/warn-c++11-extensions.cpp
+++ clang/test/SemaCXX/warn-c++11-extensions.cpp
@@ -7,3 +7,5 @@
 
 enum struct E1 { A, B }; // expected-warning {{scoped enumerations are a C++11 extension}}
 enum class E2 { C, D }; // expected-warning {{scoped enumerations are a C++11 

[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added a comment.

In D151683#4409633 , @aaron.ballman 
wrote:

> In D151683#4384017 , @erichkeane 
> wrote:
>
>> In D151683#4382408 , @philnik 
>> wrote:
>>
>>> No. I guess, since you are asking I should write one for this? Only for the 
>>> removal of `-fdouble-square-bracket-attributes`, or also for back porting 
>>> this?
>>
>> The RFC I would expect for "allow C/C++ style attributes as an extension in 
>> previous modes".  This is a pretty significant feature to allow as an 
>> extension, particularly since our two main alternative compilers (G++/MSVC) 
>> don't have this as an extension. I'd be curious how the other C compilers do 
>> this as well.
>
> I think this does warrant an RFC because it impacts both C++ and C, but I'm 
> hoping the RFC is uncontroversial. It's mostly to establish what the use 
> cases are for needing the extension. The feature is conforming as an 
> extension to both languages, and I don't know of any breakage that would come 
> from enabling it by default. I'm not certain whether we want to remove the 
> feature flag immediately or whether we'd like to give one release of warning 
> about it being removed (I'll defer to whatever @MaskRay thinks is reasonable) 
> -- that search is compelling for why it's safe to remove the option, but 
> there's plenty of proprietary code which we don't know about, so it's 
> possible the option is still used. I'd be especially curious to know if 
> anyone is using `-fno-double-square-bracket-attributes` to disable the 
> feature in a mode where it would otherwise be enabled. I'm adding the 
> `clang-vendors` group as a subscriber as an early warning that removing the 
> command line option could be a potentially breaking change.
>
> In terms of implementation work, there's still some minor stuff to address. 
> Also, please be sure to also add a release note about the changes, and a 
> potentially breaking entry for removing the command line option (assuming we 
> elect to go that route).

If allowing the extension in older language modes deems good, removing 
`-fno-double-square-bracket-attributes` seems fine if (and thanks for CCing the 
`clang-vendors` group).
If we want to play safely, we can default `-fdouble-square-bracket-attributes` 
to true in this patch and remove the option in a follow-up change possibly 
after some time.


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Chris Bieneman via Phabricator via cfe-commits]

beanz added inline comments.



Comment at: clang/test/ParserHLSL/group_shared.hlsl:14
-// expected-error@+1 {{expected expression}}
 float groupshared [[]] i = 12;
 

philnik wrote:
> beanz wrote:
> > aaron.ballman wrote:
> > > philnik wrote:
> > > > Should this also get an extension warning/should attributes be disabled 
> > > > for HLSL?
> > > CC @beanz 
> > > 
> > > I was wondering the same thing. :-)
> > By bug rather than design DXC allows C++ attribute syntax in some places 
> > for HLSL.
> > 
> > I'm totally fine with (and prefer) following the rest of the languages here 
> > and having HLSL in Clang always allow C++ attributes regardless of language 
> > version.
> Would you like some sort of warning?
Since DXC accepts the syntax without a warning/error I think we're fine without 
one here. There won't be any portability issues with code that use C++ 
attributes in HLSL unless they go back to the _extremely_ old compiler that we 
don't really support anyways.


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik added inline comments.



Comment at: clang/test/Parser/cxx-decl.cpp:316
 #if __cplusplus >= 201103L
-// expected-error@+3 {{expected}}
+// expected-error@+2 {{expected}}
 // expected-error@-3 {{expected ';' after top level declarator}}

aaron.ballman wrote:
> Huh... I wasn't expecting to see a change here because there's no attribute 
> nearby. Probably fine, but still a bit curious.
This is probably because of the whitespace trim below.



Comment at: clang/test/ParserHLSL/group_shared.hlsl:14
-// expected-error@+1 {{expected expression}}
 float groupshared [[]] i = 12;
 

beanz wrote:
> aaron.ballman wrote:
> > philnik wrote:
> > > Should this also get an extension warning/should attributes be disabled 
> > > for HLSL?
> > CC @beanz 
> > 
> > I was wondering the same thing. :-)
> By bug rather than design DXC allows C++ attribute syntax in some places for 
> HLSL.
> 
> I'm totally fine with (and prefer) following the rest of the languages here 
> and having HLSL in Clang always allow C++ attributes regardless of language 
> version.
Would you like some sort of warning?


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Chris Bieneman via Phabricator via cfe-commits]

beanz added inline comments.



Comment at: clang/test/ParserHLSL/group_shared.hlsl:14
-// expected-error@+1 {{expected expression}}
 float groupshared [[]] i = 12;
 

aaron.ballman wrote:
> philnik wrote:
> > Should this also get an extension warning/should attributes be disabled for 
> > HLSL?
> CC @beanz 
> 
> I was wondering the same thing. :-)
By bug rather than design DXC allows C++ attribute syntax in some places for 
HLSL.

I'm totally fine with (and prefer) following the rest of the languages here and 
having HLSL in Clang always allow C++ attributes regardless of language version.


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added subscribers: beanz, clang-vendors.
aaron.ballman added a comment.

In D151683#4384017 , @erichkeane 
wrote:

> In D151683#4382408 , @philnik wrote:
>
>> No. I guess, since you are asking I should write one for this? Only for the 
>> removal of `-fdouble-square-bracket-attributes`, or also for back porting 
>> this?
>
> The RFC I would expect for "allow C/C++ style attributes as an extension in 
> previous modes".  This is a pretty significant feature to allow as an 
> extension, particularly since our two main alternative compilers (G++/MSVC) 
> don't have this as an extension. I'd be curious how the other C compilers do 
> this as well.

I think this does warrant an RFC because it impacts both C++ and C, but I'm 
hoping the RFC is uncontroversial. It's mostly to establish what the use cases 
are for needing the extension. The feature is conforming as an extension to 
both languages, and I don't know of any breakage that would come from enabling 
it by default. I'm not certain whether we want to remove the feature flag 
immediately or whether we'd like to give one release of warning about it being 
removed (I'll defer to whatever @MaskRay thinks is reasonable) -- that search 
is compelling for why it's safe to remove the option, but there's plenty of 
proprietary code which we don't know about, so it's possible the option is 
still used. I'd be especially curious to know if anyone is using 
`-fno-double-square-bracket-attributes` to disable the feature in a mode where 
it would otherwise be enabled. I'm adding the `clang-vendors` group as a 
subscriber as an early warning that removing the command line option could be a 
potentially breaking change.

In terms of implementation work, there's still some minor stuff to address. 
Also, please be sure to also add a release note about the changes, and a 
potentially breaking entry for removing the command line option (assuming we 
elect to go that route).




Comment at: clang/docs/LanguageExtensions.rst:1434
 Designated initializers (N494)  C99
   C89
 Array & element qualification (N2607)   C2x
   C89
+==  
= =

You need to add an entry here as well, as this also extends C.



Comment at: clang/include/clang/Basic/DiagnosticParseKinds.td:553
 def err_while_loop_outside_of_a_function : Error<
-  "while loop outside of a function">; 
+  "while loop outside of a function">;
 def err_brackets_go_after_unqualified_id : Error<

Spurious whitespace change.



Comment at: clang/include/clang/Driver/Options.td:3530
   Values<"none,cf,cf-nochecks">;
-def mcpu_EQ : Joined<["-"], "mcpu=">, Group, 
+def mcpu_EQ : Joined<["-"], "mcpu=">, Group,
   HelpText<"For a list of available CPUs for the target use '-mcpu=help'">;

Spurious whitespace change.



Comment at: clang/lib/Driver/ToolChains/Clang.cpp:1196
   // Add include/gpu-none-libc/* to our system include path. This lets us 
use
-  // GPU-specific system headers first. 
+  // GPU-specific system headers first.
   // TODO: We need to find a way to make these headers compatible with the

Spurious whitespace change.



Comment at: clang/lib/Parse/ParseDeclCXX.cpp:4477
   SourceLocation OpenLoc = Tok.getLocation();
-  Diag(OpenLoc, diag::warn_cxx98_compat_attribute);
+  Diag(OpenLoc, getLangOpts().CPlusPlus11 ? diag::warn_cxx98_compat_attribute
+: getLangOpts().CPlusPlus ? diag::warn_ext_cxx11_attributes

Missing the same "not compatible with standards before C2x" warning as for C++ 
(might want to reword the C++ warning at the same time to fit the newer style)



Comment at: clang/test/OpenMP/assumes_messages_attr.c:57
 [[omp::directive(begin assumes ext_abc)]];
-

Spurious removal.



Comment at: clang/test/Parser/asm.c:14
   asm("foo" : "=r" (a)); // expected-error {{use of undeclared identifier 'a'}}
-  asm("foo" : : "r" (b)); // expected-error {{use of undeclared identifier 
'b'}} 
+  asm("foo" : : "r" (b)); // expected-error {{use of undeclared identifier 
'b'}}
 

Spurious whitespace change



Comment at: clang/test/Parser/cxx-decl.cpp:316
 #if __cplusplus >= 201103L
-// expected-error@+3 {{expected}}
+// expected-error@+2 {{expected}}
 // expected-error@-3 {{expected ';' after top level declarator}}

Huh... I wasn't expecting to see a change here because there's no attribute 
nearby. Probably fine, but still a bit curious.



Comment at: clang/test/Parser/cxx-decl.cpp:322
 #endif
-

Spurious change.

[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Erich Keane via Phabricator via cfe-commits]

erichkeane added a comment.

In D151683#4382408 , @philnik wrote:

> In D151683#4380877 , @erichkeane 
> wrote:
>
>> What is the justification for this?
>
> What exactly are you asking for? Why I'd like to back port it? This would 
> make quite a bit of code in libc++ simpler and avoids pit-falls where an 
> attribute works in some place in some version but not in another.
>
>> Do other compilers do this?
>
> ICC and NVC++ support this: https://godbolt.org/z/TeMnGdGsY
>
>> Was there an RFC?
>
> No. I guess, since you are asking I should write one for this? Only for the 
> removal of `-fdouble-square-bracket-attributes`, or also for back porting 
> this?

The RFC I would expect for "allow C/C++ style attributes as an extension in 
previous modes".  This is a pretty significant feature to allow as an 
extension, particularly since our two main alternative compilers (G++/MSVC) 
don't have this as an extension. I'd be curious how the other C compilers do 
this as well.


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik added a comment.

In D151683#4380877 , @erichkeane 
wrote:

> What is the justification for this?

What exactly are you asking for? Why I'd like to back port it? This would make 
quite a bit of code in libc++ simpler and avoids pit-falls where an attribute 
works in some place in some version but not in another.

> Do other compilers do this?

ICC and NVC++ support this: https://godbolt.org/z/TeMnGdGsY

> Was there an RFC?

No. I guess, since you are asking I should write one for this? Only for the 
removal of `-fdouble-square-bracket-attributes`, or also for back porting this?


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Erich Keane via Phabricator via cfe-commits]

erichkeane added a comment.

What is the justification for this?  Do other compilers do this?  Was there an 
RFC?


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik added inline comments.
Herald added subscribers: Michael137, JDevlieghere.



Comment at: clang/test/ParserHLSL/group_shared.hlsl:14
-// expected-error@+1 {{expected expression}}
 float groupshared [[]] i = 12;
 

Should this also get an extension warning/should attributes be disabled for 
HLSL?


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[PATCH] D151683: [clang] Enable C++11-style attributes in all language modes

[Nikolas Klauser via Phabricator via cfe-commits]

philnik created this revision.
philnik added reviewers: aaron.ballman, erichkeane.
Herald added subscribers: wlei, wenlei, jdoerfert, dmgreen.
Herald added a project: All.
philnik requested review of this revision.
Herald added subscribers: lldb-commits, cfe-commits, jplehr, sstefan1, MaskRay.
Herald added a reviewer: jdoerfert.
Herald added projects: clang, LLDB.

This also removes the `-fdouble-square-bracket-attributes` command line flag, 
which seems to not be used anywhere. At least a code search exclusively found 
mentions of it in documentation: 
https://sourcegraph.com/search?q=context:global+-fdouble-square-bracket-attributes+-file:clang/*+-file:test/Sema/*+-file:test/Parser/*+-file:test/AST/*+-file:test/Preprocessor/*+-file:test/Misc/*+archived:yes=standard=0=repo


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Files:
  clang/docs/LanguageExtensions.rst
  clang/include/clang/Basic/DiagnosticParseKinds.td
  clang/include/clang/Basic/LangOptions.def
  clang/include/clang/Driver/Options.td
  clang/include/clang/Parse/Parser.h
  clang/lib/Basic/Attributes.cpp
  clang/lib/Driver/ToolChains/Clang.cpp
  clang/lib/Lex/Lexer.cpp
  clang/lib/Parse/ParseDecl.cpp
  clang/lib/Parse/ParseDeclCXX.cpp
  clang/test/AST/ast-dump-attr.m
  clang/test/AST/ast-dump-c-attr.c
  clang/test/AST/attr-annotate-type.c
  clang/test/CodeGen/attr-btf_type_tag-func.c
  clang/test/CodeGen/attr-btf_type_tag-var.c
  clang/test/Frontend/noderef.c
  clang/test/OpenMP/assumes_messages_attr.c
  clang/test/OpenMP/openmp_attribute_compat.cpp
  clang/test/Parser/asm.c
  clang/test/Parser/c2x-attributes.c
  clang/test/Parser/c2x-attributes.m
  clang/test/Parser/cxx-decl.cpp
  clang/test/Parser/objc-attr.m
  clang/test/ParserHLSL/group_shared.hlsl
  clang/test/Preprocessor/has_c_attribute.c
  clang/test/Sema/annotate-type.c
  clang/test/Sema/annotate.c
  clang/test/Sema/attr-availability-square-brackets.c
  clang/test/Sema/attr-external-source-symbol-cxx.cpp
  clang/test/Sema/attr-external-source-symbol.c
  clang/test/Sema/attr-likelihood.c
  clang/test/Sema/attr-objc-bridge-related.m
  clang/test/Sema/attr-regparm.c
  clang/test/Sema/attr-type-safety.c
  clang/test/Sema/c2x-noreturn.c
  clang/test/Sema/internal_linkage.c
  clang/test/Sema/matrix-type-builtins.c
  clang/test/Sema/neon-vector-types.c
  clang/test/Sema/overload-arm-mve.c
  clang/test/Sema/overloadable.c
  clang/test/Sema/vector-gcc-compat.c
  clang/test/SemaCXX/attr-cxx-disabled.cpp
  clang/test/SemaObjC/attr-objc-gc.m
  clang/unittests/AST/AttrTest.cpp
  clang/utils/TableGen/ClangAttrEmitter.cpp
  lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
===
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -575,7 +575,6 @@
 // FIXME: We should ask the driver for the appropriate default flags.
 lang_opts.GNUMode = true;
 lang_opts.GNUKeywords = true;
-lang_opts.DoubleSquareBracketAttributes = true;
 lang_opts.CPlusPlus11 = true;
 
 // The Darwin libc expects this macro to be set.
Index: clang/utils/TableGen/ClangAttrEmitter.cpp
===
--- clang/utils/TableGen/ClangAttrEmitter.cpp
+++ clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3387,14 +3387,10 @@
   // If this is the C++11 variety, also add in the LangOpts test.
   if (Variety == "CXX11")
 Test += " && LangOpts.CPlusPlus11";
-  else if (Variety == "C2x")
-Test += " && LangOpts.DoubleSquareBracketAttributes";
 } else if (Variety == "CXX11")
   // C++11 mode should be checked against LangOpts, which is presumed to be
   // present in the caller.
   Test = "LangOpts.CPlusPlus11";
-else if (Variety == "C2x")
-  Test = "LangOpts.DoubleSquareBracketAttributes";
 
 std::string TestStr = !Test.empty()
   ? Test + " ? " + llvm::itostr(Version) + " : 0"
Index: clang/unittests/AST/AttrTest.cpp
===
--- clang/unittests/AST/AttrTest.cpp
+++ clang/unittests/AST/AttrTest.cpp
@@ -157,7 +157,7 @@
   AST = buildASTFromCodeWithArgs(R"c(
 __auto_type [[clang::annotate_type("auto")]] auto_var = 1;
   )c",
- {"-fdouble-square-bracket-attributes"},
+ {},
  "input.c");
 
   {
Index: clang/test/SemaObjC/attr-objc-gc.m
===
--- clang/test/SemaObjC/attr-objc-gc.m
+++ clang/test/SemaObjC/attr-objc-gc.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -fdouble-square-bracket-attributes -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only