release/19.x: [Clang] Instantiate Typedefs referenced by type alias deduction guides (#111804) #112293
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llvm#111804) TypedefNameDecl referenced by a synthesized CTAD guide for type aliases was not transformed previously, resulting in a substitution failure in BuildDeductionGuideForTypeAlias() when substituting into the right-hand-side deduction guide. This patch fixes it in the way we have been doing since https://reviews.llvm.org/D80743. We transform all the function parameters, parenting referenced TypedefNameDecls with the CXXDeductionGuideDecl. Then we instantiate these declarations in FindInstantiatedDecl() as we build up the eventual deduction guide, using the mechanism introduced in D80743 Fixes llvm#111508 (cherry picked from commit 0bc02b9)
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@erichkeane What do you think about merging this PR to the release branch? |
llvmbot
added
clang
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@llvm/pr-subscribers-clang Author: None (llvmbot) ChangesBackport 0bc02b9 Requested by: @zyn0217 Full diff: https://github.com/llvm/llvm-project/pull/112293.diff 2 Files Affected:
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<TypedefNameDecl *> &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<TypedefNameDecl *> TypedefDecls;
+ llvm::SmallVector<QualType> 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<float>::B out(100); // deduced to Out<float>::A<float>;
static_assert(__is_same(decltype(out), Out<float>::A<float>));
}
+
+namespace GH111508 {
+
+template <typename V> struct S {
+ using T = V;
+ T Data;
+};
+
+template <typename V> using Alias = S<V>;
+
+Alias A(42);
+
+} // namespace GH111508
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erichkeane
approved these changes
Oct 15, 2024
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Backport 0bc02b9
Requested by: @zyn0217