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[clang] Call ActOnCaseExpr even if the 'case' is missing #166326

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Merged
merged 1 commit into from
Nov 5, 2025
Merged

[clang] Call ActOnCaseExpr even if the 'case' is missing #166326

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2 changes: 1 addition & 1 deletion clang/lib/Parse/ParseStmt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -813,7 +813,7 @@ StmtResult Parser::ParseCaseStatement(ParsedStmtContext StmtCtx,
return StmtError();
}
} else {
LHS = Expr;
LHS = Actions.ActOnCaseExpr(CaseLoc, Expr);
MissingCase = false;
}

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6 changes: 6 additions & 0 deletions clang/test/SemaCXX/constant-expression-cxx14.cpp
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Expand Up @@ -1450,3 +1450,9 @@ namespace GH149500 {
unsigned int * p = &(*(unsigned int *)0x400);
static const void *q = &(*(const struct sysrq_key_op *)0);
}

constexpr bool missingCase() {
switch (1) {
1u: return false; // expected-error {{expected 'case' keyword before expression}}
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@AaronBallman AaronBallman Nov 4, 2025

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I'm a bit confused; we already emit this diagnostic today without your changes: https://godbolt.org/z/4379s9zGf

You mention this is about getting the usual conversions to happen, but those only need to happen for well-formed code, right?

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@tbaederr tbaederr Nov 4, 2025

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It's not about the diagnostic, it's about clang crashing in constant evaluation because the type of the case stmt expression is wrong: #165555 (the second example further down).

I don't know if the conversions only need to happen for well-formed code or not. If not, we should instead mark the case stmt as having errors I guess, but just letting it through like that trips up a couple of places

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@AaronBallman AaronBallman Nov 4, 2025

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Ah, I see now that my godbolt link does show the issue with an asserts build, that makes more sense now. Thank you!

}
}