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[clang] Remove hasValue() check in RecordExprEvaluator::VisitCXXConstructExpr() #154610

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Merged
merged 1 commit into from
Aug 23, 2025
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[clang] Remove hasValue() check in RecordExprEvaluator::VisitCXXConstructExpr() #154610

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4 changes: 0 additions & 4 deletions clang/lib/AST/ExprConstant.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11045,10 +11045,6 @@ bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,

bool ZeroInit = E->requiresZeroInitialization();
if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) {
// If we've already performed zero-initialization, we're already done.
if (Result.hasValue())
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@shafik shafik Aug 25, 2025

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Was this code do nothing then? It looks like this check came in with e637cbe

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@efriedma-quic efriedma-quic Aug 25, 2025

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When it's working correctly, it allows skipping work zero-initializing something that's already zero-initialized, I think. But that assumes we maintain an invariant about exactly when values are absent, vs. uninitialized. We don't maintain that invariant for anonymous structs. (We probably could, but it's a little tricky to implement correctly for nested anonymous structs.)

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@shafik shafik Aug 25, 2025

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Makes sense, maybe worth a FIXME, probably not a huge win though.

return true;

if (ZeroInit)
return ZeroInitialization(E, T);

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16 changes: 16 additions & 0 deletions clang/test/SemaCXX/constant-expression-cxx11.cpp
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Expand Up @@ -2645,3 +2645,19 @@ namespace GH150709 {
static_assert((e2[0].*mp)() == 1, ""); // expected-error {{constant expression}}
static_assert((g.*mp)() == 1, ""); // expected-error {{constant expression}}
}

namespace GH154567 {
struct T {
int i;
};

struct S {
struct { // expected-warning {{GNU extension}}
T val;
};
constexpr S() : val() {}
};

constexpr S s{};
static_assert(s.val.i == 0, "");
}