[clang] 801c78d - Revert "Reland "[clang][Sema] Use original template pattern when declaring implicit deduction guides for nested template classes" (#69676)"

[Antonio Abbatangelo via cfe-commits]

Author: Antonio Abbatangelo
Date: 2023-11-01T18:10:02-04:00
New Revision: 801c78d5b474c2319aa8ead44db7ba8cacac4714

URL: https://github.com/llvm/llvm-project/commit/801c78d5b474c2319aa8ead44db7ba8cacac4714
DIFF: https://github.com/llvm/llvm-project/commit/801c78d5b474c2319aa8ead44db7ba8cacac4714.diff

LOG: Revert "Reland "[clang][Sema] Use original template pattern when declaring implicit deduction guides for nested template classes" (#69676)"

This reverts commit f418319730341e9d41ce8ead6fbfe5603c343985.

Failing test case: https://github.com/llvm/llvm-project/pull/69676#issuecomment-1789255366

Added: 
    

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Sema/SemaTemplate.cpp
    clang/test/SemaTemplate/nested-deduction-guides.cpp

Removed: 
    clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3198d6bfe75a2e8..4696836b3a00caa 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -665,11 +665,6 @@ Bug Fixes to C++ Support
   declaration definition. Fixes:
   (`#61763 <https://github.com/llvm/llvm-project/issues/61763>`_)
 
-- Fix a bug where implicit deduction guides are not correctly generated for nested template
-  classes. Fixes:
-  (`#46200 <https://github.com/llvm/llvm-project/issues/46200>`_)
-  (`#57812 <https://github.com/llvm/llvm-project/issues/57812>`_)
-
 - Diagnose use of a variable-length array in a coroutine. The design of
   coroutines is such that it is not possible to support VLA use. Fixes:
   (`#65858 <https://github.com/llvm/llvm-project/issues/65858>`_)

diff  --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 59721c8dc664aa9..9044400fbb1f3f3 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -2253,7 +2253,6 @@ struct ConvertConstructorToDeductionGuideTransform {
 
   Sema &SemaRef;
   ClassTemplateDecl *Template;
-  ClassTemplateDecl *NestedPattern = nullptr;
 
   DeclContext *DC = Template->getDeclContext();
   CXXRecordDecl *Primary = Template->getTemplatedDecl();
@@ -2333,9 +2332,6 @@ struct ConvertConstructorToDeductionGuideTransform {
       Args.addOuterRetainedLevel();
     }
 
-    if (NestedPattern)
-      Args.addOuterRetainedLevels(NestedPattern->getTemplateDepth());
-
     FunctionProtoTypeLoc FPTL = CD->getTypeSourceInfo()->getTypeLoc()
                                    .getAsAdjusted<FunctionProtoTypeLoc>();
     assert(FPTL && "no prototype for constructor declaration");
@@ -2445,17 +2441,10 @@ struct ConvertConstructorToDeductionGuideTransform {
     SmallVector<QualType, 4> ParamTypes;
     const FunctionProtoType *T = TL.getTypePtr();
 
-    MultiLevelTemplateArgumentList OuterInstantiationArgs;
-    if (NestedPattern)
-      OuterInstantiationArgs = SemaRef.getTemplateInstantiationArgs(Template);
-
     //    -- The types of the function parameters are those of the constructor.
     for (auto *OldParam : TL.getParams()) {
       ParmVarDecl *NewParam =
           transformFunctionTypeParam(OldParam, Args, MaterializedTypedefs);
-      if (NestedPattern && NewParam)
-        NewParam = transformFunctionTypeParam(NewParam, OuterInstantiationArgs,
-                                              MaterializedTypedefs);
       if (!NewParam)
         return QualType();
       ParamTypes.push_back(NewParam->getType());
@@ -2661,24 +2650,13 @@ void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,
   if (BuildingDeductionGuides.isInvalid())
     return;
 
-  // If the template is nested, then we need to use the original
-  // pattern to iterate over the constructors.
-  ClassTemplateDecl *Pattern = Transform.Template;
-  while (Pattern->getInstantiatedFromMemberTemplate()) {
-    if (Pattern->isMemberSpecialization())
-      break;
-    Pattern = Pattern->getInstantiatedFromMemberTemplate();
-    Transform.NestedPattern = Pattern;
-  }
-
   // Convert declared constructors into deduction guide templates.
   // FIXME: Skip constructors for which deduction must necessarily fail (those
   // for which some class template parameter without a default argument never
   // appears in a deduced context).
-  ContextRAII SavedContext(*this, Pattern->getTemplatedDecl());
   llvm::SmallPtrSet<NamedDecl *, 8> ProcessedCtors;
   bool AddedAny = false;
-  for (NamedDecl *D : LookupConstructors(Pattern->getTemplatedDecl())) {
+  for (NamedDecl *D : LookupConstructors(Transform.Primary)) {
     D = D->getUnderlyingDecl();
     if (D->isInvalidDecl() || D->isImplicit())
       continue;
@@ -2724,8 +2702,6 @@ void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,
           Transform.buildSimpleDeductionGuide(Transform.DeducedType))
           ->getTemplatedDecl())
       ->setDeductionCandidateKind(DeductionCandidate::Copy);
-
-  SavedContext.pop();
 }
 
 /// Diagnose the presence of a default template argument on a

diff  --git a/clang/test/SemaTemplate/nested-deduction-guides.cpp b/clang/test/SemaTemplate/nested-deduction-guides.cpp
index 38410b93ead3b97..2c5dda456a138a8 100644
--- a/clang/test/SemaTemplate/nested-deduction-guides.cpp
+++ b/clang/test/SemaTemplate/nested-deduction-guides.cpp
@@ -4,15 +4,10 @@
 template<typename T> struct A {
   template<typename U> struct B {
     B(...);
-    B(const B &) = default;
   };
   template<typename U> B(U) -> B<U>;
 };
 A<void>::B b = 123;
-A<void>::B copy = b;
 
 using T = decltype(b);
 using T = A<void>::B<int>;
-
-using Copy = decltype(copy);
-using Copy = A<void>::B<int>;

diff  --git a/clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp b/clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp
deleted file mode 100644
index 10b70f9c8c4f357..000000000000000
--- a/clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp
+++ /dev/null
@@ -1,15 +0,0 @@
-// RUN: %clang_cc1 -std=c++17 -verify %s
-// expected-no-diagnostics
-
-template<class T> struct S {
-    template<class U> struct N {
-        N(T) {}
-        N(T, U) {}
-        template<class V> N(V, U) {}
-    };
-};
-
-S<int>::N x{"a", 1};
-
-using T = decltype(x);
-using T = S<int>::N<int>;