[clang] Avoid inheriting [[noreturn]] in explicit function template specializations #150003
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…late specializations
snarang181
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@llvm/pr-subscribers-clang Author: Samarth Narang (snarang181) ChangesThis patch fixes incorrect behavior in Clang where [[noreturn]] (either spelled or inferred) was being inherited by explicit specializations of function templates or member function templates, even when those specializations returned normally. Follow up on #145166 Full diff: https://github.com/llvm/llvm-project/pull/150003.diff 3 Files Affected:
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 14403e65e8f42..bb412ef6788e7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -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;
}
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 78f4804202ddc..a61d10c166578 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -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()) &&
diff --git a/clang/test/SemaCXX/wreturn-always-throws.cpp b/clang/test/SemaCXX/wreturn-always-throws.cpp
index addcadd1183dc..c307bc675c14b 100644
--- a/clang/test/SemaCXX/wreturn-always-throws.cpp
+++ b/clang/test/SemaCXX/wreturn-always-throws.cpp
@@ -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
+
+
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zwuis
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Jul 22, 2025
zwuis
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I think we need to test partial specialization as well. |
Add -Winvalid-noreturn diagnostic in LIT test
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alexfh
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Jul 24, 2025
There was a problem hiding this comment.
The fix looks good now.
We might still want to revisit the original patch though (#145166 (comment)).
mahesh-attarde
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Jul 28, 2025
…pecializations (llvm#150003) This patch fixes incorrect behavior in Clang where [[noreturn]] (either spelled or inferred) was being inherited by explicit specializations of function templates or member function templates, even when those specializations returned normally. Follow up on llvm#145166
|
This fixes cases that are broken on the 21.x release branch - see #151742. Therefore, this should probably be backported there. |
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/cherry-pick 22fef00 |
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/pull-request #151752 |
cor3ntin
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Aug 2, 2025
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… specializations. (#151815) Addressing #150003 (comment)
llvm-sync bot
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Aug 4, 2025
…in explicit specializations. (#151815) Addressing llvm/llvm-project#150003 (comment)
tru
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Aug 5, 2025
…pecializations (llvm#150003) This patch fixes incorrect behavior in Clang where [[noreturn]] (either spelled or inferred) was being inherited by explicit specializations of function templates or member function templates, even when those specializations returned normally. Follow up on llvm#145166 (cherry picked from commit 22fef00)
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This patch fixes incorrect behavior in Clang where [[noreturn]] (either spelled or inferred) was being inherited by explicit specializations of function templates or member function templates, even when those specializations returned normally.
Follow up on #145166