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

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Merged
merged 1 commit into from
Aug 4, 2025
Merged

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

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6 changes: 5 additions & 1 deletion clang/lib/Sema/SemaStmt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2284,7 +2284,11 @@ StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
// we can diagnose if we don't see any variable declarations. This
// covers a case like declaring a typedef, function, or structure
// 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
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3 changes: 1 addition & 2 deletions clang/test/Sema/for.c
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Expand Up @@ -26,6 +26,5 @@ void b11 (void) { for (static _Thread_local struct { int i; } s;s.i;); } /* c11-
#endif

void b12(void) {
for(_Static_assert(1, "");;) {} /* c11-warning {{non-variable declaration in 'for' loop is a C23 extension}}
c23-warning {{non-variable declaration in 'for' loop is incompatible with C standards before C23}} */
for(_Static_assert(1, "");;) {} /* okay, _Static_assert declares *no* identifiers */
}