diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 5708e691d0849..5a39fe32f7585 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -353,6 +353,10 @@ Improvements to Clang's time-trace Bug Fixes in This Version ------------------------- +- Clang's ``-Wundefined-func-template`` no longer warns on pure virtual + functions. + (`#74016 `_) + - Fixed missing warnings when comparing mismatched enumeration constants in C (`#29217 `). diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index bd221763b319d..45acbf197ea6b 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -18982,8 +18982,10 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func, // Note that we skip the implicit instantiation of templates that are only // used in unused default arguments or by recursive calls to themselves. // This is formally non-conforming, but seems reasonable in practice. - bool NeedDefinition = !IsRecursiveCall && (OdrUse == OdrUseContext::Used || - NeededForConstantEvaluation); + bool NeedDefinition = + !IsRecursiveCall && + (OdrUse == OdrUseContext::Used || + (NeededForConstantEvaluation && !Func->isPureVirtual())); // C++14 [temp.expl.spec]p6: // If a template [...] is explicitly specialized then that specialization diff --git a/clang/test/SemaTemplate/instantiate-pure-virtual-function.cpp b/clang/test/SemaTemplate/instantiate-pure-virtual-function.cpp new file mode 100644 index 0000000000000..caec42b6b77f9 --- /dev/null +++ b/clang/test/SemaTemplate/instantiate-pure-virtual-function.cpp @@ -0,0 +1,67 @@ +// RUN: %clang_cc1 -fsyntax-only -verify -Wundefined-func-template %s + +namespace GH74016 { + template class B { + public: + constexpr void foo(const T &) { bar(1); } + virtual constexpr void bar(unsigned int) = 0; + }; + + template class D : public B { + public: + constexpr void bar(unsigned int) override {} + }; + + void test() { + auto t = D(); + t.foo(0); + } +}; + +namespace call_pure_virtual_function_from_virtual { + template class B { + public: + const void foo(const T &) { B::bar(1); } // expected-warning {{instantiation of function 'call_pure_virtual_function_from_virtual::B::bar' required here, but no definition is available}} + // expected-note@-1 {{add an explicit instantiation declaration to suppress this warning if 'call_pure_virtual_function_from_virtual::B::bar' is explicitly instantiated in another translation unit}} + virtual const void bar(unsigned int) = 0; // expected-note {{forward declaration of template entity is here}} + }; + + template class D : public B { + public: + const void bar(unsigned int) override {} + }; + + void test() { + auto t = D(); + t.foo(0); // expected-note {{in instantiation of member function 'call_pure_virtual_function_from_virtual::B::foo' requested here}} + } +}; + +namespace non_pure_virtual_function { + template class B { + public: + constexpr void foo(const T &) { bar(1); } + + virtual constexpr void bar(unsigned int); // expected-warning {{inline function 'non_pure_virtual_function::B::bar' is not defined}} + // expected-note@-1 {{forward declaration of template entity is here}} + // expected-note@-2 {{forward declaration of template entity is here}} + // expected-note@-3 {{forward declaration of template entity is here}} + }; + + template class D : public B { // expected-warning {{instantiation of function 'non_pure_virtual_function::B::bar' required here, but no definition is available}} +// expected-warning@-1 {{instantiation of function 'non_pure_virtual_function::B::bar' required here, but no definition is available}} +// expected-warning@-2 {{instantiation of function 'non_pure_virtual_function::B::bar' required here, but no definition is available}} +// expected-note@-3 {{add an explicit instantiation declaration to suppress this warning if 'non_pure_virtual_function::B::bar' is explicitly instantiated in another translation unit}} +// expected-note@-4 {{add an explicit instantiation declaration to suppress this warning if 'non_pure_virtual_function::B::bar' is explicitly instantiated in another translation unit}} +// expected-note@-5 {{add an explicit instantiation declaration to suppress this warning if 'non_pure_virtual_function::B::bar' is explicitly instantiated in another translation unit}} +// expected-note@-6 {{used here}} + + public: + constexpr void bar(unsigned int) override { } + }; + + void test() { + auto t = D(); + t.foo(0); + } +};