================
@@ -2902,28 +2902,41 @@ static void handleWarnUnusedResult(Sema &S, Decl *D,
const ParsedAttr &AL) {
}
StringRef Str;
- if (AL.isStandardAttributeSyntax() && !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. C23 supports this attribute
- // with the message; no extension warning is needed there beyond the one
- // already issued for accepting attributes in older modes.
- const LangOptions &LO = S.getLangOpts();
- if (AL.getNumArgs() == 1) {
- if (LO.CPlusPlus && !LO.CPlusPlus20)
- S.Diag(AL.getLoc(), diag::ext_cxx20_attr) << AL;
-
- 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.
----------------
AaronBallman wrote:
```suggestion
```
As part of that change, I dropped this comment entirely.
https://github.com/llvm/llvm-project/pull/148090
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