diff --git a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp index 0602d07c6b9b0d..1bf82b31def977 100644 --- a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp +++ b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp @@ -69,8 +69,8 @@ class ExtractTypeForDeductionGuide ExtractTypeForDeductionGuide( Sema &SemaRef, llvm::SmallVectorImpl &MaterializedTypedefs, - ClassTemplateDecl *NestedPattern, - const MultiLevelTemplateArgumentList *OuterInstantiationArgs) + ClassTemplateDecl *NestedPattern = nullptr, + const MultiLevelTemplateArgumentList *OuterInstantiationArgs = nullptr) : Base(SemaRef), MaterializedTypedefs(MaterializedTypedefs), NestedPattern(NestedPattern), OuterInstantiationArgs(OuterInstantiationArgs) { @@ -1263,10 +1263,25 @@ FunctionTemplateDecl *DeclareAggregateDeductionGuideForTypeAlias( getRHSTemplateDeclAndArgs(SemaRef, AliasTemplate).first; if (!RHSTemplate) return nullptr; + + llvm::SmallVector TypedefDecls; + llvm::SmallVector NewParamTypes; + ExtractTypeForDeductionGuide TypeAliasTransformer(SemaRef, TypedefDecls); + for (QualType P : ParamTypes) { + QualType Type = TypeAliasTransformer.TransformType(P); + if (Type.isNull()) + return nullptr; + NewParamTypes.push_back(Type); + } + auto *RHSDeductionGuide = SemaRef.DeclareAggregateDeductionGuideFromInitList( - RHSTemplate, ParamTypes, Loc); + RHSTemplate, NewParamTypes, Loc); if (!RHSDeductionGuide) return nullptr; + + for (TypedefNameDecl *TD : TypedefDecls) + TD->setDeclContext(RHSDeductionGuide->getTemplatedDecl()); + return BuildDeductionGuideForTypeAlias(SemaRef, AliasTemplate, RHSDeductionGuide, Loc); } diff --git a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp index 5392573fcdb9d5..675c32a81f1ae8 100644 --- a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp +++ b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp @@ -481,3 +481,16 @@ struct Out { Out::B out(100); // deduced to Out::A; static_assert(__is_same(decltype(out), Out::A)); } + +namespace GH111508 { + +template struct S { + using T = V; + T Data; +}; + +template using Alias = S; + +Alias A(42); + +} // namespace GH111508