diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 2d0e663d93e46f..55e1670b7e2fa0 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -63,6 +63,12 @@ ABI Changes in This Version MSVC uses a different mangling for these objects, compatibility is not affected. (#GH85423). +- Fixed Microsoft calling convention for returning certain classes with a + templated constructor. If a class has a templated constructor, it should + be returned indirectly even if it meets all the other requirements for + returning a class in a register. This affects some uses of std::pair. + (#GH86384). + AST Dumping Potentially Breaking Changes ---------------------------------------- diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp index d38a26940a3cb6..d47927745759e1 100644 --- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp +++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp @@ -1131,9 +1131,15 @@ static bool isTrivialForMSVC(const CXXRecordDecl *RD, QualType Ty, return false; if (RD->hasNonTrivialCopyAssignment()) return false; - for (const CXXConstructorDecl *Ctor : RD->ctors()) - if (Ctor->isUserProvided()) - return false; + for (const Decl *D : RD->decls()) { + if (auto *Ctor = dyn_cast(D)) { + if (Ctor->isUserProvided()) + return false; + } else if (auto *Template = dyn_cast(D)) { + if (isa(Template->getTemplatedDecl())) + return false; + } + } if (RD->hasNonTrivialDestructor()) return false; return true; diff --git a/clang/test/CodeGen/arm64-microsoft-arguments.cpp b/clang/test/CodeGen/arm64-microsoft-arguments.cpp index e8309888dcfe21..85472645acb3b3 100644 --- a/clang/test/CodeGen/arm64-microsoft-arguments.cpp +++ b/clang/test/CodeGen/arm64-microsoft-arguments.cpp @@ -201,3 +201,18 @@ S11 f11() { S11 x; return func11(x); } + +// GH86384 +// Pass and return object with template constructor (pass directly, +// return indirectly). +// CHECK: define dso_local void @"?f12@@YA?AUS12@@XZ"(ptr dead_on_unwind inreg noalias writable sret(%struct.S12) align 4 {{.*}}) +// CHECK: call void @"?func12@@YA?AUS12@@U1@@Z"(ptr dead_on_unwind inreg writable sret(%struct.S12) align 4 {{.*}}, i64 {{.*}}) +struct S12 { + template S12(T*) {} + int x; +}; +S12 func12(S12 x); +S12 f12() { + S12 x((int*)0); + return func12(x); +}