================
@@ -1880,16 +1880,70 @@ Sema::ConditionResult
Parser::ParseCXXCondition(StmtResult *InitStmt,
return Sema::ConditionError();
}
+ if (!getLangOpts().CPlusPlus && Tok.is(tok::kw___extension__)) {
+ // In C, the first clause of a condition may be a declaration used as an
+ // init-statement (C2y), and that declaration may be prefixed by one or
more
+ // __extension__ markers. Consume them up front -- mirroring
block-statement
+ // parsing -- so the disambiguation below sees the real start of the
+ // declaration. The markers also silence extension diagnostics for the rest
+ // of the condition, including the diagnostic for the init-statement
+ // extension itself.
+ std::optional<ExtensionRAIIObject> ExtensionGuard;
+ ExtensionGuard.emplace(Diags);
+ while (TryConsumeToken(tok::kw___extension__))
+ ;
+ }
+
ParsedAttributes attrs(AttrFactory);
- MaybeParseCXX11Attributes(attrs);
+ bool ParsedAttrs = MaybeParseCXX11Attributes(attrs);
+ if (!getLangOpts().CPlusPlus)
+ ParsedAttrs = MaybeParseGNUAttributes(attrs) || ParsedAttrs;
const auto WarnOnInit = [this, &CK] {
- Diag(Tok.getLocation(), getLangOpts().CPlusPlus17
- ? diag::warn_cxx14_compat_init_statement
- : diag::ext_init_statement)
- << (CK == Sema::ConditionKind::Switch);
+ if (getLangOpts().CPlusPlus)
+ Diag(Tok.getLocation(), getLangOpts().CPlusPlus17
+ ? diag::warn_cxx14_compat_init_statement
+ : diag::ext_init_statement)
+ << (CK == Sema::ConditionKind::Switch);
+ else
+ Diag(Tok.getLocation(), getLangOpts().C2y
+ ? diag::warn_c2y_compat_decl_statement
+ : diag::ext_c2y_decl_statement)
+ << (CK == Sema::ConditionKind::Switch);
};
+ if (!getLangOpts().CPlusPlus) {
+ if (isDeclarationStatement() && !isCXXSimpleDeclaration(false)) {
+ // Accept a C2y declaration, *only* if it's not a simple declaration.
+ WarnOnInit();
+ DeclGroupPtrTy DG;
+ SourceLocation DeclStart = Tok.getLocation(), DeclEnd;
+ ParsedAttributes DeclSpecAttrs(AttrFactory);
+ // C2y replaces the init-statement in C++17 to be a declaration instead.
+ DG = ParseDeclaration(DeclaratorContext::SelectionInit, DeclEnd, attrs,
+ DeclSpecAttrs);
+ StmtResult DeclStmt = Actions.ActOnDeclStmt(DG, DeclStart, DeclEnd);
+ if (InitStmt == nullptr)
+ Diag(DeclStmt.get()->getBeginLoc(), diag::err_expected_expression)
----------------
AaronBallman wrote:
`ActOnDeclStmt` can return unusable results, so this needs to handle the case
where the decl statement is unusable (I think we're missing test coverage
because I'd have expected a crash here in that case).
https://github.com/llvm/llvm-project/pull/198244
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