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[C] static_assert in a for loop is not an extension (#151955)

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The original wording can be squinted at to pretend this was always
allowed. GCC squints at it that way, so we're doing the same and no
longer issuing an extension diagnostic for use of static_assert in the
condition-1 of a for loop in C.

Fixes #149633

(cherry picked from commit cb50d78a0063244434d883d89ddda7f74abbffc9)
This commit is contained in:
Aaron Ballman 2025-08-04 12:46:53 -04:00 committed by Tobias Hieta
parent 1d46440e9f
commit d502822e68
2 changed files with 6 additions and 3 deletions
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6
clang/lib/Sema/SemaStmt.cpp
View File

@ -2287,7 +2287,11 @@ StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
// we can diagnose if we don't see any variable declarations. This // we can diagnose if we don't see any variable declarations. This
// covers a case like declaring a typedef, function, or structure // covers a case like declaring a typedef, function, or structure
// type rather than a variable. // type rather than a variable.
NonVarSeen = DI; //
// Note, _Static_assert is acceptable because it does not declare an
// identifier at all, so "for object having" does not apply.
if (!isa<StaticAssertDecl>(DI))
NonVarSeen = DI;
} }
} }
// Diagnose if we saw a non-variable declaration but no variable // Diagnose if we saw a non-variable declaration but no variable

3
clang/test/Sema/for.c
View File

@ -26,6 +26,5 @@ void b11 (void) { for (static _Thread_local struct { int i; } s;s.i;); } /* c11-
#endif #endif
void b12(void) { void b12(void) {
for(_Static_assert(1, "");;) {} /* c11-warning {{non-variable declaration in 'for' loop is a C23 extension}} for(_Static_assert(1, "");;) {} /* okay, _Static_assert declares *no* identifiers */
c23-warning {{non-variable declaration in 'for' loop is incompatible with C standards before C23}} */
} }