https://github.com/zebullax updated
https://github.com/llvm/llvm-project/pull/148090
>From 11909560ed6cb4e56192fbbfe4d8b1cdf58e1cb1 Mon Sep 17 00:00:00 2001
From: zebullax <zebul...@gmail.com>
Date: Fri, 11 Jul 2025 09:12:44 +0900
Subject: [PATCH 1/6] Build argument string for clang::warn_unused_result
Preserve the argument-clause for `warn-unused-result` when under clang:: scope.
We are not touching gnu:: scope for now as it's an error for GCC to have that
string. Personally I think it would be ok to relax it here too as we are not
introducing breakage to currently passing code, but feedback is to go slowly
about it.
---
clang/lib/Sema/SemaDeclAttr.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 7ebb53318702c..221197b3849e0 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2902,7 +2902,8 @@ static void handleWarnUnusedResult(Sema &S, Decl *D,
const ParsedAttr &AL) {
}
StringRef Str;
- if (AL.isStandardAttributeSyntax() && !AL.getScopeName()) {
+ if (AL.isStandardAttributeSyntax()
+ && (!AL.getScopeName() || AL.isClangScope())) {
// The standard attribute cannot be applied to variable declarations such
// as a function pointer.
if (isa<VarDecl>(D))
>From 7d1b223472514fa09574fb4ee49518f912353494 Mon Sep 17 00:00:00 2001
From: zebullax <zebul...@gmail.com>
Date: Fri, 11 Jul 2025 15:51:22 +0900
Subject: [PATCH 2/6] Add unit test to check reason string on clang scope
Signed-off-by: zebullax <zebul...@gmail.com>
Fix scope in UT
Signed-off-by: zebullax <zebul...@gmail.com>
Fix UT
Signed-off-by: zebullax <zebul...@gmail.com>
Remove warn on attaching clang scoped to var decl
Signed-off-by: zebullax <zebul...@gmail.com>
Fix EOL
Signed-off-by: zebullax <zebul...@gmail.com>
---
clang/lib/Sema/SemaDeclAttr.cpp | 2 +-
clang/test/SemaCXX/warn-unused-result.cpp | 18 ++++++++++++++++++
2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 221197b3849e0..c9822369e8652 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2906,7 +2906,7 @@ static void handleWarnUnusedResult(Sema &S, Decl *D,
const ParsedAttr &AL) {
&& (!AL.getScopeName() || AL.isClangScope())) {
// The standard attribute cannot be applied to variable declarations such
// as a function pointer.
- if (isa<VarDecl>(D))
+ if (!AL.isClangScope() && isa<VarDecl>(D))
S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type)
<< AL << AL.isRegularKeywordAttribute()
<< ExpectedFunctionOrClassOrEnum;
diff --git a/clang/test/SemaCXX/warn-unused-result.cpp
b/clang/test/SemaCXX/warn-unused-result.cpp
index fa7540c116e67..fe7d5ea79e9a7 100644
--- a/clang/test/SemaCXX/warn-unused-result.cpp
+++ b/clang/test/SemaCXX/warn-unused-result.cpp
@@ -364,3 +364,21 @@ void id_print_name() {
((int(*)())f)();
}
} // namespace GH117975
+
+namespace BuildStringOnClangScope {
+
+[[clang::warn_unused_result("Discarded result")]]
+bool makeClangTrue() { return true; }
+
+[[gnu::warn_unused_result("Discarded result")]]
+bool makeGccTrue() { return true; }
+
+void doClangThings() {
+ makeClangTrue(); // expected-warning {{ignoring return value of function
declared with 'clang::warn_unused_result' attribute: Discarded result}}
+}
+
+void doGccThings() {
+ makeGccTrue(); // expected-warning {{ignoring return value of function
declared with 'gnu::warn_unused_result' attribute}}
+}
+
+}
>From b110d634b6b64b8d96d63e0a43e3283809e46af0 Mon Sep 17 00:00:00 2001
From: zebullax <zebul...@gmail.com>
Date: Fri, 11 Jul 2025 18:02:53 +0900
Subject: [PATCH 3/6] Update release notes
Signed-off-by: zebullax <zebul...@gmail.com>
---
clang/docs/ReleaseNotes.rst | 3 +++
1 file changed, 3 insertions(+)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9e16613826a77..7797b14e49f55 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -464,6 +464,9 @@ related warnings within the method body.
- Clang now disallows the use of attributes applied before an
``extern template`` declaration (#GH79893).
+- Clang will print the "reason" string argument passed on to
+ `[[clang::warn_unused_result("reason")]]` as part of the warning diagnostic
+
Improvements to Clang's diagnostics
-----------------------------------
>From 0cbcc955ccc9d9be8e15cbc094a8eaa3235e0bfd Mon Sep 17 00:00:00 2001
From: zebullax <zebul...@gmail.com>
Date: Fri, 11 Jul 2025 20:36:53 +0900
Subject: [PATCH 4/6] Update clang/docs/ReleaseNotes.rst
Co-authored-by: Aaron Ballman <aa...@aaronballman.com>
---
clang/docs/ReleaseNotes.rst | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7797b14e49f55..edad96c15ca9f 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -465,7 +465,7 @@ related warnings within the method body.
``extern template`` declaration (#GH79893).
- Clang will print the "reason" string argument passed on to
- `[[clang::warn_unused_result("reason")]]` as part of the warning diagnostic
+ ``[[clang::warn_unused_result("reason")]]`` as part of the warning
diagnostic.
Improvements to Clang's diagnostics
-----------------------------------
>From 04c46dab4a249d018632b0bba04c1224c0b93096 Mon Sep 17 00:00:00 2001
From: zebullax <zebul...@gmail.com>
Date: Fri, 11 Jul 2025 20:37:24 +0900
Subject: [PATCH 5/6] Fix format
Signed-off-by: zebullax <zebul...@gmail.com>
---
clang/lib/Sema/SemaDeclAttr.cpp | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index c9822369e8652..f4b0f9fa74b77 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2902,8 +2902,8 @@ static void handleWarnUnusedResult(Sema &S, Decl *D,
const ParsedAttr &AL) {
}
StringRef Str;
- if (AL.isStandardAttributeSyntax()
- && (!AL.getScopeName() || AL.isClangScope())) {
+ if (AL.isStandardAttributeSyntax() &&
+ (!AL.getScopeName() || AL.isClangScope())) {
// The standard attribute cannot be applied to variable declarations such
// as a function pointer.
if (!AL.isClangScope() && isa<VarDecl>(D))
>From e70bba4cdf1093a7c80463833d0dbf99916aa8b8 Mon Sep 17 00:00:00 2001
From: zebullax <zebul...@gmail.com>
Date: Fri, 11 Jul 2025 22:14:21 +0900
Subject: [PATCH 6/6] Extract the clang scope branch to bypass cxx17,20
standard verification
Signed-off-by: zebullax <zebul...@gmail.com>
---
clang/lib/Sema/SemaDeclAttr.cpp | 60 +++++++++++++++++++--------------
1 file changed, 34 insertions(+), 26 deletions(-)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index f4b0f9fa74b77..f28ecc9738fc6 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -2902,33 +2902,41 @@ static void handleWarnUnusedResult(Sema &S, Decl *D,
const ParsedAttr &AL) {
}
StringRef Str;
- if (AL.isStandardAttributeSyntax() &&
- (!AL.getScopeName() || AL.isClangScope())) {
- // The standard attribute cannot be applied to variable declarations such
- // as a function pointer.
- if (!AL.isClangScope() && isa<VarDecl>(D))
- S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type)
- << AL << AL.isRegularKeywordAttribute()
- << ExpectedFunctionOrClassOrEnum;
-
- // If this is spelled as the standard C++17 attribute, but not in C++17,
- // warn about using it as an extension. If there are attribute arguments,
- // then claim it's a C++20 extension instead.
- // FIXME: If WG14 does not seem likely to adopt the same feature, add an
- // extension warning for C23 mode.
- const LangOptions &LO = S.getLangOpts();
- if (AL.getNumArgs() == 1) {
- if (LO.CPlusPlus && !LO.CPlusPlus20)
- S.Diag(AL.getLoc(), diag::ext_cxx20_attr) << AL;
-
- // Since this is spelled [[nodiscard]], get the optional string
- // literal. If in C++ mode, but not in C++20 mode, diagnose as an
- // extension.
- // FIXME: C23 should support this feature as well, even as an extension.
- if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, nullptr))
+ if (AL.isStandardAttributeSyntax()) {
+ // If this is spelled [[clang::warn_unused_result]] we look for an optional
+ // string literal. This is not gated behind any specific version of the
+ // standard.
+ if (AL.isClangScope()) {
+ if (AL.getNumArgs() == 1 &&
+ !S.checkStringLiteralArgumentAttr(AL, 0, Str, nullptr))
return;
- } else if (LO.CPlusPlus && !LO.CPlusPlus17)
- S.Diag(AL.getLoc(), diag::ext_cxx17_attr) << AL;
+ } else if (!AL.getScopeName()) {
+ // The standard attribute cannot be applied to variable declarations such
+ // as a function pointer.
+ if (isa<VarDecl>(D))
+ S.Diag(AL.getLoc(), diag::warn_attribute_wrong_decl_type)
+ << AL << AL.isRegularKeywordAttribute()
+ << ExpectedFunctionOrClassOrEnum;
+
+ // If this is spelled as the standard C++17 attribute, but not in C++17,
+ // warn about using it as an extension. If there are attribute arguments,
+ // then claim it's a C++20 extension instead.
+ // FIXME: If WG14 does not seem likely to adopt the same feature, add an
+ // extension warning for C23 mode.
+ const LangOptions &LO = S.getLangOpts();
+ if (AL.getNumArgs() == 1) {
+ if (LO.CPlusPlus && !LO.CPlusPlus20)
+ S.Diag(AL.getLoc(), diag::ext_cxx20_attr) << AL;
+
+ // Since this is spelled [[nodiscard]], get the optional string
+ // literal. If in C++ mode, but not in C++20 mode, diagnose as an
+ // extension.
+ // FIXME: C23 should support this feature as well, even as an
extension.
+ if (!S.checkStringLiteralArgumentAttr(AL, 0, Str, nullptr))
+ return;
+ } else if (LO.CPlusPlus && !LO.CPlusPlus17)
+ S.Diag(AL.getLoc(), diag::ext_cxx17_attr) << AL;
+ }
}
if ((!AL.isGNUAttribute() &&
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