https://github.com/zyn0217 updated
https://github.com/llvm/llvm-project/pull/132669
>From 2894090c356438867c182fd76c9b89354c0bafee Mon Sep 17 00:00:00 2001
From: Younan Zhang <zyn7...@gmail.com>
Date: Mon, 24 Mar 2025 12:43:17 +0800
Subject: [PATCH 1/2] [Clang] Fix the assertion condition after b8d1f3d6
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Thanks to the example provided by @MagentaTreehouse, I realized the
assertion I added didn't cover all valid cases like, when inheriting
from a class template specialization, the source of a synthesized
template parameter might be an implicit specialization, whose inner
function template is thus living at depth 0, for which we don’t want
it to overflow too.
---
clang/lib/Sema/SemaTemplateDeductionGuide.cpp | 10 ++--
clang/test/SemaTemplate/deduction-guide.cpp | 48 +++++++++++++++++++
2 files changed, 52 insertions(+), 6 deletions(-)
diff --git a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
index 9cfdb7596b660..6685fdd60dc09 100644
--- a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
+++ b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
@@ -376,12 +376,10 @@ struct ConvertConstructorToDeductionGuideTransform {
if (NestedPattern)
Args.addOuterRetainedLevels(NestedPattern->getTemplateDepth());
auto [Depth, Index] = getDepthAndIndex(Param);
- // Depth can still be 0 if FTD belongs to an explicit class template
- // specialization with an empty template parameter list. In that case,
- // we don't want the NewDepth to overflow, and it should remain 0.
- assert(Depth ||
- cast<ClassTemplateSpecializationDecl>(FTD->getDeclContext())
- ->isExplicitSpecialization());
+ // Depth can be 0 if FTD belongs to a non-template class/a class
+ // template specialization with an empty template parameter list. In
+ // that case, we don't want the NewDepth to overflow, and it should
+ // remain 0.
NamedDecl *NewParam = transformTemplateParameter(
SemaRef, DC, Param, Args, Index + Depth1IndexAdjustment,
Depth ? Depth - 1 : 0);
diff --git a/clang/test/SemaTemplate/deduction-guide.cpp
b/clang/test/SemaTemplate/deduction-guide.cpp
index ecd152abebd74..6db132ca37c7e 100644
--- a/clang/test/SemaTemplate/deduction-guide.cpp
+++ b/clang/test/SemaTemplate/deduction-guide.cpp
@@ -723,3 +723,51 @@ void test() { NewDeleteAllocator abc(42); } //
expected-error {{no viable constr
// CHECK-NEXT: `-ParmVarDecl {{.+}} 'T'
} // namespace GH128691
+
+namespace GH132616_DeductionGuide {
+
+template <class T> struct A {
+ template <class U>
+ A(U);
+};
+
+template <typename>
+struct B : A<int> {
+ using A::A;
+};
+
+template <class T>
+B(T) -> B<T>;
+
+B b(24);
+
+// CHECK-LABEL: Dumping GH132616_DeductionGuide::<deduction guide for B>:
+// CHECK-NEXT: FunctionTemplateDecl {{.+}} implicit <deduction guide for B>
+// CHECK-NEXT: |-TemplateTypeParmDecl {{.+}} typename depth 0 index 0
+// CHECK-NEXT: |-TemplateTypeParmDecl {{.+}} class depth 0 index 1 U
+// CHECK-NEXT: `-CXXDeductionGuideDecl {{.+}} implicit <deduction guide for B>
'auto (U) -> B<type-parameter-0-0>'
+// CHECK-NEXT: `-ParmVarDecl {{.+}} 'U'
+
+struct C {
+ template <class U>
+ C(U);
+};
+
+template <typename>
+struct D : C {
+ using C::C;
+};
+
+template <class T>
+D(T) -> D<T>;
+
+D d(24);
+
+// CHECK-LABEL: Dumping GH132616_DeductionGuide::<deduction guide for D>:
+// CHECK-NEXT: FunctionTemplateDecl {{.+}} implicit <deduction guide for D>
+// CHECK-NEXT: |-TemplateTypeParmDecl {{.+}} typename depth 0 index 0
+// CHECK-NEXT: |-TemplateTypeParmDecl {{.+}} class depth 0 index 1 U
+// CHECK-NEXT: `-CXXDeductionGuideDecl {{.+}} implicit <deduction guide for D>
'auto (U) -> D<type-parameter-0-0>'
+// CHECK-NEXT: `-ParmVarDecl {{.+}} 'U'
+
+} // namespace GH132616_DeductionGuide
>From b7bef605503bc566dd0624b338d7ce6bec856fd3 Mon Sep 17 00:00:00 2001
From: Younan Zhang <zyn7...@gmail.com>
Date: Mon, 24 Mar 2025 13:16:15 +0800
Subject: [PATCH 2/2] Drive-by fix for
https://github.com/llvm/llvm-project/pull/132061#discussion_r2008756718
---
clang/lib/Sema/SemaTemplateDeductionGuide.cpp | 27 +++++++++----------
1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
index 6685fdd60dc09..3b2129e0df815 100644
--- a/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
+++ b/clang/lib/Sema/SemaTemplateDeductionGuide.cpp
@@ -968,6 +968,19 @@ getRHSTemplateDeclAndArgs(Sema &SemaRef,
TypeAliasTemplateDecl *AliasTemplate) {
return {Template, AliasRhsTemplateArgs};
}
+bool IsNonDeducedArgument(const TemplateArgument &TA) {
+ // The following cases indicate the template argument is non-deducible:
+ // 1. The result is null. E.g. When it comes from a default template
+ // argument that doesn't appear in the alias declaration.
+ // 2. The template parameter is a pack and that cannot be deduced from
+ // the arguments within the alias declaration.
+ // Non-deducible template parameters will persist in the transformed
+ // deduction guide.
+ return TA.isNull() ||
+ (TA.getKind() == TemplateArgument::Pack &&
+ llvm::any_of(TA.pack_elements(), IsNonDeducedArgument));
+}
+
// Build deduction guides for a type alias template from the given underlying
// deduction guide F.
FunctionTemplateDecl *
@@ -1031,20 +1044,6 @@ BuildDeductionGuideForTypeAlias(Sema &SemaRef,
AliasRhsTemplateArgs, TDeduceInfo, DeduceResults,
/*NumberOfArgumentsMustMatch=*/false);
- static std::function<bool(const TemplateArgument &TA)> IsNonDeducedArgument =
- [](const TemplateArgument &TA) {
- // The following cases indicate the template argument is non-deducible:
- // 1. The result is null. E.g. When it comes from a default template
- // argument that doesn't appear in the alias declaration.
- // 2. The template parameter is a pack and that cannot be deduced
from
- // the arguments within the alias declaration.
- // Non-deducible template parameters will persist in the transformed
- // deduction guide.
- return TA.isNull() ||
- (TA.getKind() == TemplateArgument::Pack &&
- llvm::any_of(TA.pack_elements(), IsNonDeducedArgument));
- };
-
SmallVector<TemplateArgument> DeducedArgs;
SmallVector<unsigned> NonDeducedTemplateParamsInFIndex;
// !!NOTE: DeduceResults respects the sequence of template parameters of
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