[clang] Revert "[clang] Fix CTAD for aggregates for nested template classes" (PR #78541)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: None (antangelo)

<details>
<summary>Changes</summary>

Reverts llvm/llvm-project#<!-- -->78387

The added tests are failing on several build bots.

---
Full diff: https://github.com/llvm/llvm-project/pull/78541.diff


4 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (-3) 
- (modified) clang/lib/Sema/SemaInit.cpp (+1-8) 
- (modified) clang/lib/Sema/SemaTemplate.cpp (+4-17) 
- (modified) clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp (+1-18) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index d70d6dfd5df9fe3..cf52c1e66b91b42 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -972,9 +972,6 @@ Bug Fixes to C++ Support
   (`#57410 <https://github.com/llvm/llvm-project/issues/57410>`_) and
   (`#76604 <https://github.com/llvm/llvm-project/issues/57410>`_)
 
-- Fixes CTAD for aggregates on nested template classes. Fixes:
-  (`#77599 <https://github.com/llvm/llvm-project/issues/77599>`_)
-
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 - Fixed an import failure of recursive friend class template.
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 48235941f62aa23..408ee5f775804b6 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -10718,14 +10718,7 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
     bool HasAnyDeductionGuide = false;
 
     auto SynthesizeAggrGuide = [&](InitListExpr *ListInit) {
-      auto *Pattern = Template;
-      while (Pattern->getInstantiatedFromMemberTemplate()) {
-        if (Pattern->isMemberSpecialization())
-          break;
-        Pattern = Pattern->getInstantiatedFromMemberTemplate();
-      }
-
-      auto *RD = cast<CXXRecordDecl>(Pattern->getTemplatedDecl());
+      auto *RD = cast<CXXRecordDecl>(Template->getTemplatedDecl());
       if (!(RD->getDefinition() && RD->isAggregate()))
         return;
       QualType Ty = Context.getRecordType(RD);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 839d508b911f063..0655d3633520676 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -2418,9 +2418,6 @@ struct ConvertConstructorToDeductionGuideTransform {
     QualType Result = SemaRef.BuildFunctionType(DeducedType, ParamTypes, Loc,
                                                 DeductionGuideName, EPI);
     TypeSourceInfo *TSI = SemaRef.Context.getTrivialTypeSourceInfo(Result, Loc);
-    if (NestedPattern)
-      TSI = SemaRef.SubstType(TSI, OuterInstantiationArgs, Loc,
-                              DeductionGuideName);
 
     FunctionProtoTypeLoc FPTL =
         TSI->getTypeLoc().castAs<FunctionProtoTypeLoc>();
@@ -2428,13 +2425,9 @@ struct ConvertConstructorToDeductionGuideTransform {
     // Build the parameters, needed during deduction / substitution.
     SmallVector<ParmVarDecl*, 4> Params;
     for (auto T : ParamTypes) {
-      auto *TSI = SemaRef.Context.getTrivialTypeSourceInfo(T, Loc);
-      if (NestedPattern)
-        TSI = SemaRef.SubstType(TSI, OuterInstantiationArgs, Loc,
-                                DeclarationName());
-      ParmVarDecl *NewParam =
-          ParmVarDecl::Create(SemaRef.Context, DC, Loc, Loc, nullptr,
-                              TSI->getType(), TSI, SC_None, nullptr);
+      ParmVarDecl *NewParam = ParmVarDecl::Create(
+          SemaRef.Context, DC, Loc, Loc, nullptr, T,
+          SemaRef.Context.getTrivialTypeSourceInfo(T, Loc), SC_None, nullptr);
       NewParam->setScopeInfo(0, Params.size());
       FPTL.setParam(Params.size(), NewParam);
       Params.push_back(NewParam);
@@ -2677,14 +2670,8 @@ FunctionTemplateDecl *Sema::DeclareImplicitDeductionGuideFromInitList(
   if (BuildingDeductionGuides.isInvalid())
     return nullptr;
 
-  ClassTemplateDecl *Pattern =
-      Transform.NestedPattern ? Transform.NestedPattern : Transform.Template;
-  ContextRAII SavedContext(*this, Pattern->getTemplatedDecl());
-
-  auto *DG = cast<FunctionTemplateDecl>(
+  return cast<FunctionTemplateDecl>(
       Transform.buildSimpleDeductionGuide(ParamTypes));
-  SavedContext.pop();
-  return DG;
 }
 
 void Sema::DeclareImplicitDeductionGuides(TemplateDecl *Template,
diff --git a/clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp b/clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp
index f3af6e8d6c17da0..c44ec6918c7afb1 100644
--- a/clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp
+++ b/clang/test/SemaTemplate/nested-implicit-deduction-guides.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -std=c++20 -verify %s
+// expected-no-diagnostics
 
 template<class T> struct S {
     template<class U> struct N {
@@ -57,21 +58,3 @@ template<class X> struct requires_clause {
 requires_clause<int>::B req(1, 2);
 using RC = decltype(req);
 using RC = requires_clause<int>::B<int>;
-
-template<typename X> struct nested_init_list {
-    template<C<X> Y>
-    struct B { // #INIT_LIST_INNER
-        X x;
-        Y y;
-    };
-};
-
-nested_init_list<int>::B nil {1, 2};
-using NIL = decltype(nil);
-using NIL = nested_init_list<int>::B<int>;
-
-// expected-error at +1 {{no viable constructor or deduction guide for deduction of template arguments of 'B'}}
-nested_init_list<int>::B nil_invalid {1, ""};
-// expected-note@#INIT_LIST_INNER {{candidate template ignored: substitution failure [with Y = const char *]: constraints not satisfied for class template 'B' [with Y = const char *]}}
-// expected-note@#INIT_LIST_INNER {{candidate function template not viable: requires 1 argument, but 2 were provided}}
-// expected-note@#INIT_LIST_INNER {{candidate function template not viable: requires 0 arguments, but 2 were provided}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/78541