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[clang] Avoid inheriting [[noreturn]] in explicit function template specializations #150003

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Merged
merged 4 commits into from
Jul 24, 2025
Merged

[clang] Avoid inheriting [[noreturn]] in explicit function template specializations #150003

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ff5dfd4
[Sema] Avoid attaching 'noreturn' attribute to explicit function temp…
snarang181 Jul 22, 2025
eba957a
Add LIT test
snarang181 Jul 22, 2025
0228989
Update test case
snarang181 Jul 22, 2025
4db6e19
Elaborate comments on why we skip explicit specializations
snarang181 Jul 22, 2025
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8 changes: 8 additions & 0 deletions clang/lib/Sema/SemaDecl.cpp
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Expand Up @@ -3267,6 +3267,14 @@ void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
if (isa<UsedAttr>(I) || isa<RetainAttr>(I))
continue;

if (isa<InferredNoReturnAttr>(I)) {
if (auto *FD = dyn_cast<FunctionDecl>(New)) {
if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
continue; // Don't propagate inferred noreturn attributes to explicit
// specializations.
}
}

if (mergeDeclAttribute(*this, New, I, LocalAMK))
foundAny = true;
}
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3 changes: 3 additions & 0 deletions clang/lib/Sema/SemaDeclAttr.cpp
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Expand Up @@ -1970,6 +1970,9 @@ void clang::inferNoReturnAttr(Sema &S, const Decl *D) {
if (!FD)
return;

if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
return; // Don't infer noreturn for explicit specializations.

auto *NonConstFD = const_cast<FunctionDecl *>(FD);
DiagnosticsEngine &Diags = S.getDiagnostics();
if (Diags.isIgnored(diag::warn_falloff_nonvoid, FD->getLocation()) &&
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15 changes: 15 additions & 0 deletions clang/test/SemaCXX/wreturn-always-throws.cpp
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Expand Up @@ -44,3 +44,18 @@ void testTemplates() {
throwErrorTemplate("ERROR");
(void)ensureZeroTemplate(42);
}

// Ensure that explicit specialization of a member function does not inherit
// the warning from the primary template.

template<typename T>
struct S {
void f();
};

template<typename T>
void S<T>::f() { throw 0; }
template<>
void S<int>::f() {} // expected-no-diagnostics