Revert "[clang] fix P3310 overload resolution flag propagation" (llvm#125710)

DavidSpickett · Icohedron · commit 9dccc290f48c · 2025-02-11T23:34:36.000Z
Reverts llvm#125372 due to lldb builds failing: https://lab.llvm.org/buildbot/#/builders/59/builds/12223 We need to decide how to update LLDB's code.
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
@@ -1841,23 +1841,15 @@ class ClassTemplateSpecializationDecl : public CXXRecordDecl,
   LLVM_PREFERRED_TYPE(TemplateSpecializationKind)
   unsigned SpecializationKind : 3;
 
-  /// Indicate that we have matched a parameter pack with a non pack
-  /// argument, when the opposite match is also allowed (strict pack match).
-  /// This needs to be cached as deduction is performed during declaration,
-  /// and we need the information to be preserved so that it is consistent
-  /// during instantiation.
-  bool MatchedPackOnParmToNonPackOnArg : 1;
-
 protected:
   ClassTemplateSpecializationDecl(ASTContext &Context, Kind DK, TagKind TK,
                                   DeclContext *DC, SourceLocation StartLoc,
                                   SourceLocation IdLoc,
                                   ClassTemplateDecl *SpecializedTemplate,
                                   ArrayRef<TemplateArgument> Args,
-                                  bool MatchedPackOnParmToNonPackOnArg,
                                   ClassTemplateSpecializationDecl *PrevDecl);
 
-  ClassTemplateSpecializationDecl(ASTContext &C, Kind DK);
+  explicit ClassTemplateSpecializationDecl(ASTContext &C, Kind DK);
 
 public:
   friend class ASTDeclReader;
@@ -1867,7 +1859,7 @@ class ClassTemplateSpecializationDecl : public CXXRecordDecl,
   Create(ASTContext &Context, TagKind TK, DeclContext *DC,
          SourceLocation StartLoc, SourceLocation IdLoc,
          ClassTemplateDecl *SpecializedTemplate,
-         ArrayRef<TemplateArgument> Args, bool MatchedPackOnParmToNonPackOnArg,
+         ArrayRef<TemplateArgument> Args,
          ClassTemplateSpecializationDecl *PrevDecl);
   static ClassTemplateSpecializationDecl *CreateDeserialized(ASTContext &C,
                                                              GlobalDeclID ID);
@@ -1938,10 +1930,6 @@ class ClassTemplateSpecializationDecl : public CXXRecordDecl,
     SpecializationKind = TSK;
   }
 
-  bool hasMatchedPackOnParmToNonPackOnArg() const {
-    return MatchedPackOnParmToNonPackOnArg;
-  }
-
   /// Get the point of instantiation (if any), or null if none.
   SourceLocation getPointOfInstantiation() const {
     return PointOfInstantiation;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
@@ -13499,8 +13499,8 @@ class Sema final : public SemaBase {
   bool InstantiateClassTemplateSpecialization(
       SourceLocation PointOfInstantiation,
       ClassTemplateSpecializationDecl *ClassTemplateSpec,
-      TemplateSpecializationKind TSK, bool Complain,
-      bool PrimaryHasMatchedPackOnParmToNonPackOnArg);
+      TemplateSpecializationKind TSK, bool Complain = true,
+      bool PrimaryHasMatchedPackOnParmToNonPackOnArg = false);
 
   /// Instantiates the definitions of all of the member
   /// of the given class, which is an instantiation of a class template
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
@@ -6321,9 +6321,9 @@ ExpectedDecl ASTNodeImporter::VisitClassTemplateSpecializationDecl(
     updateLookupTableForTemplateParameters(*ToTPList);
   } else { // Not a partial specialization.
     if (GetImportedOrCreateDecl(
-            D2, D, Importer.getToContext(), D->getTagKind(), DC, *BeginLocOrErr,
-            *IdLocOrErr, ClassTemplate, TemplateArgs,
-            D->hasMatchedPackOnParmToNonPackOnArg(), PrevDecl))
+            D2, D, Importer.getToContext(), D->getTagKind(), DC,
+            *BeginLocOrErr, *IdLocOrErr, ClassTemplate, TemplateArgs,
+            PrevDecl))
       return D2;
 
     // Update InsertPos, because preceding import calls may have invalidated
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
@@ -957,20 +957,18 @@ FunctionTemplateSpecializationInfo *FunctionTemplateSpecializationInfo::Create(
 // ClassTemplateSpecializationDecl Implementation
 //===----------------------------------------------------------------------===//
 
-ClassTemplateSpecializationDecl::ClassTemplateSpecializationDecl(
-    ASTContext &Context, Kind DK, TagKind TK, DeclContext *DC,
-    SourceLocation StartLoc, SourceLocation IdLoc,
-    ClassTemplateDecl *SpecializedTemplate, ArrayRef<TemplateArgument> Args,
-    bool MatchedPackOnParmToNonPackOnArg,
-    ClassTemplateSpecializationDecl *PrevDecl)
+ClassTemplateSpecializationDecl::
+ClassTemplateSpecializationDecl(ASTContext &Context, Kind DK, TagKind TK,
+                                DeclContext *DC, SourceLocation StartLoc,
+                                SourceLocation IdLoc,
+                                ClassTemplateDecl *SpecializedTemplate,
+                                ArrayRef<TemplateArgument> Args,
+                                ClassTemplateSpecializationDecl *PrevDecl)
     : CXXRecordDecl(DK, TK, Context, DC, StartLoc, IdLoc,
                     SpecializedTemplate->getIdentifier(), PrevDecl),
-      SpecializedTemplate(SpecializedTemplate),
-      TemplateArgs(TemplateArgumentList::CreateCopy(Context, Args)),
-      SpecializationKind(TSK_Undeclared),
-      MatchedPackOnParmToNonPackOnArg(MatchedPackOnParmToNonPackOnArg) {
-  assert(DK == Kind::ClassTemplateSpecialization ||
-         MatchedPackOnParmToNonPackOnArg == false);
+    SpecializedTemplate(SpecializedTemplate),
+    TemplateArgs(TemplateArgumentList::CreateCopy(Context, Args)),
+    SpecializationKind(TSK_Undeclared) {
 }
 
 ClassTemplateSpecializationDecl::ClassTemplateSpecializationDecl(ASTContext &C,
@@ -979,14 +977,18 @@ ClassTemplateSpecializationDecl::ClassTemplateSpecializationDecl(ASTContext &C,
                     SourceLocation(), nullptr, nullptr),
       SpecializationKind(TSK_Undeclared) {}
 
-ClassTemplateSpecializationDecl *ClassTemplateSpecializationDecl::Create(
-    ASTContext &Context, TagKind TK, DeclContext *DC, SourceLocation StartLoc,
-    SourceLocation IdLoc, ClassTemplateDecl *SpecializedTemplate,
-    ArrayRef<TemplateArgument> Args, bool MatchedPackOnParmToNonPackOnArg,
-    ClassTemplateSpecializationDecl *PrevDecl) {
-  auto *Result = new (Context, DC) ClassTemplateSpecializationDecl(
-      Context, ClassTemplateSpecialization, TK, DC, StartLoc, IdLoc,
-      SpecializedTemplate, Args, MatchedPackOnParmToNonPackOnArg, PrevDecl);
+ClassTemplateSpecializationDecl *
+ClassTemplateSpecializationDecl::Create(ASTContext &Context, TagKind TK,
+                                        DeclContext *DC,
+                                        SourceLocation StartLoc,
+                                        SourceLocation IdLoc,
+                                        ClassTemplateDecl *SpecializedTemplate,
+                                        ArrayRef<TemplateArgument> Args,
+                                   ClassTemplateSpecializationDecl *PrevDecl) {
+  auto *Result =
+      new (Context, DC) ClassTemplateSpecializationDecl(
+          Context, ClassTemplateSpecialization, TK, DC, StartLoc, IdLoc,
+          SpecializedTemplate, Args, PrevDecl);
   Result->setMayHaveOutOfDateDef(false);
 
   // If the template decl is incomplete, copy the external lexical storage from
@@ -1173,10 +1175,7 @@ ClassTemplatePartialSpecializationDecl::ClassTemplatePartialSpecializationDecl(
     ClassTemplatePartialSpecializationDecl *PrevDecl)
     : ClassTemplateSpecializationDecl(
           Context, ClassTemplatePartialSpecialization, TK, DC, StartLoc, IdLoc,
-          // Tracking MatchedPackOnParmToNonPackOnArg for Partial
-          // Specializations is not needed.
-          SpecializedTemplate, Args, /*MatchedPackOnParmToNonPackOnArg=*/false,
-          PrevDecl),
+          SpecializedTemplate, Args, PrevDecl),
       TemplateParams(Params), InstantiatedFromMember(nullptr, false) {
   if (AdoptTemplateParameterList(Params, this))
     setInvalidDecl();
diff --git a/clang/lib/AST/JSONNodeDumper.cpp b/clang/lib/AST/JSONNodeDumper.cpp
@@ -1003,11 +1003,6 @@ void JSONNodeDumper::VisitRecordDecl(const RecordDecl *RD) {
 void JSONNodeDumper::VisitCXXRecordDecl(const CXXRecordDecl *RD) {
   VisitRecordDecl(RD);
 
-  if (const auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(RD)) {
-    if (CTSD->hasMatchedPackOnParmToNonPackOnArg())
-      JOS.attribute("strict-pack-match", true);
-  }
-
   // All other information requires a complete definition.
   if (!RD->isCompleteDefinition())
     return;
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
@@ -2525,11 +2525,8 @@ void TextNodeDumper::VisitCXXRecordDecl(const CXXRecordDecl *D) {
     OS << " instantiated_from";
     dumpPointer(Instance);
   }
-  if (const auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(D)) {
+  if (const auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(D))
     dumpTemplateSpecializationKind(CTSD->getSpecializationKind());
-    if (CTSD->hasMatchedPackOnParmToNonPackOnArg())
-      OS << " strict-pack-match";
-  }
 
   dumpNestedNameSpecifier(D->getQualifier());
 
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
@@ -3651,7 +3651,7 @@ QualType Sema::CheckTemplateIdType(TemplateName Name,
           ClassTemplate->getDeclContext(),
           ClassTemplate->getTemplatedDecl()->getBeginLoc(),
           ClassTemplate->getLocation(), ClassTemplate, CTAI.CanonicalConverted,
-          CTAI.MatchedPackOnParmToNonPackOnArg, nullptr);
+          nullptr);
       ClassTemplate->AddSpecialization(Decl, InsertPos);
       if (ClassTemplate->isOutOfLine())
         Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
@@ -8526,8 +8526,7 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
     // this explicit specialization or friend declaration.
     Specialization = ClassTemplateSpecializationDecl::Create(
         Context, Kind, DC, KWLoc, TemplateNameLoc, ClassTemplate,
-        CTAI.CanonicalConverted, CTAI.MatchedPackOnParmToNonPackOnArg,
-        PrevDecl);
+        CTAI.CanonicalConverted, PrevDecl);
     Specialization->setTemplateArgsAsWritten(TemplateArgs);
     SetNestedNameSpecifier(*this, Specialization, SS);
     if (TemplateParameterLists.size() > 0) {
@@ -9870,8 +9869,7 @@ DeclResult Sema::ActOnExplicitInstantiation(
     // this explicit specialization.
     Specialization = ClassTemplateSpecializationDecl::Create(
         Context, Kind, ClassTemplate->getDeclContext(), KWLoc, TemplateNameLoc,
-        ClassTemplate, CTAI.CanonicalConverted,
-        CTAI.MatchedPackOnParmToNonPackOnArg, PrevDecl);
+        ClassTemplate, CTAI.CanonicalConverted, PrevDecl);
     SetNestedNameSpecifier(*this, Specialization, SS);
 
     // A MSInheritanceAttr attached to the previous declaration must be
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -3341,6 +3341,8 @@ FinishTemplateArgumentDeduction(
     return ConstraintsNotSatisfied
                ? TemplateDeductionResult::ConstraintsNotSatisfied
                : TemplateDeductionResult::SubstitutionFailure;
+  if (InstCTAI.MatchedPackOnParmToNonPackOnArg)
+    Info.setMatchedPackOnParmToNonPackOnArg();
 
   TemplateParameterList *TemplateParams = Template->getTemplateParameters();
   for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -4038,7 +4038,7 @@ TemplateDeclInstantiator::VisitClassTemplateSpecializationDecl(
       ClassTemplateSpecializationDecl::Create(
           SemaRef.Context, D->getTagKind(), Owner, D->getBeginLoc(),
           D->getLocation(), InstClassTemplate, CTAI.CanonicalConverted,
-          CTAI.MatchedPackOnParmToNonPackOnArg, PrevDecl);
+          PrevDecl);
   InstD->setTemplateArgsAsWritten(InstTemplateArgs);
 
   // Add this partial specialization to the set of class template partial
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
@@ -9399,8 +9399,7 @@ bool Sema::RequireCompleteTypeImpl(SourceLocation Loc, QualType T,
         runWithSufficientStackSpace(Loc, [&] {
           Diagnosed = InstantiateClassTemplateSpecialization(
               Loc, ClassTemplateSpec, TSK_ImplicitInstantiation,
-              /*Complain=*/Diagnoser,
-              ClassTemplateSpec->hasMatchedPackOnParmToNonPackOnArg());
+              /*Complain=*/Diagnoser);
         });
         Instantiated = true;
       }
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2532,7 +2532,6 @@ RedeclarableResult ASTDeclReader::VisitClassTemplateSpecializationDeclImpl(
   D->TemplateArgs = TemplateArgumentList::CreateCopy(C, TemplArgs);
   D->PointOfInstantiation = readSourceLocation();
   D->SpecializationKind = (TemplateSpecializationKind)Record.readInt();
-  D->MatchedPackOnParmToNonPackOnArg = Record.readBool();
 
   bool writtenAsCanonicalDecl = Record.readInt();
   if (writtenAsCanonicalDecl) {
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -1843,7 +1843,6 @@ void ASTDeclWriter::VisitClassTemplateSpecializationDecl(
   Record.AddTemplateArgumentList(&D->getTemplateArgs());
   Record.AddSourceLocation(D->getPointOfInstantiation());
   Record.push_back(D->getSpecializationKind());
-  Record.push_back(D->hasMatchedPackOnParmToNonPackOnArg());
   Record.push_back(D->isCanonicalDecl());
 
   if (D->isCanonicalDecl()) {
diff --git a/clang/test/AST/ast-dump-templates.cpp b/clang/test/AST/ast-dump-templates.cpp
diff --git a/clang/test/AST/gen_ast_dump_json_test.py b/clang/test/AST/gen_ast_dump_json_test.py
diff --git a/clang/test/SemaTemplate/cwg2398.cpp b/clang/test/SemaTemplate/cwg2398.cpp
