Revert "[clang][modules] Add support for merging lifetime-extended te…

…mporaries"

This reverts commit 85c7438.

clang/include/clang/AST/DeclCXX.h

@@ -3041,9 +3041,7 @@ class NamespaceAliasDecl : public NamedDecl,
 
 /// Implicit declaration of a temporary that was materialized by
 /// a MaterializeTemporaryExpr and lifetime-extended by a declaration
-class LifetimeExtendedTemporaryDecl final
-    : public Decl,
-      public Mergeable<LifetimeExtendedTemporaryDecl> {
+class LifetimeExtendedTemporaryDecl final : public Decl {
   friend class MaterializeTemporaryExpr;
   friend class ASTDeclReader;
 

clang/include/clang/AST/TextNodeDumper.h

@@ -346,8 +346,6 @@ class TextNodeDumper
   void VisitObjCPropertyImplDecl(const ObjCPropertyImplDecl *D);
   void VisitBlockDecl(const BlockDecl *D);
   void VisitConceptDecl(const ConceptDecl *D);
-  void
-  VisitLifetimeExtendedTemporaryDecl(const LifetimeExtendedTemporaryDecl *D);
 };
 
 } // namespace clang

clang/include/clang/Serialization/ASTReader.h

@@ -551,14 +551,6 @@ class ASTReader
   llvm::DenseMap<Decl*, llvm::SmallVector<NamedDecl*, 2>>
     AnonymousDeclarationsForMerging;
 
-  /// Key used to identify LifetimeExtendedTemporaryDecl for merging,
-  /// containing the lifetime-extending declaration and the mangling number.
-  using LETemporaryKey = std::pair<Decl *, unsigned>;
-
-  /// Map of already deserialiazed temporaries.
-  llvm::DenseMap<LETemporaryKey, LifetimeExtendedTemporaryDecl *>
-      LETemporaryForMerging;
-
   struct FileDeclsInfo {
     ModuleFile *Mod = nullptr;
     ArrayRef<serialization::LocalDeclID> Decls;

clang/lib/AST/TextNodeDumper.cpp

@@ -1338,17 +1338,6 @@ void TextNodeDumper::VisitFunctionDecl(const FunctionDecl *D) {
     OS << " <<<NULL params x " << D->getNumParams() << ">>>";
 }
 
-void TextNodeDumper::VisitLifetimeExtendedTemporaryDecl(
-    const LifetimeExtendedTemporaryDecl *D) {
-  OS << " extended by ";
-  dumpBareDeclRef(D->getExtendingDecl());
-  OS << " mangling ";
-  {
-    ColorScope Color(OS, ShowColors, ValueColor);
-    OS << D->getManglingNumber();
-  }
-}
-
 void TextNodeDumper::VisitFieldDecl(const FieldDecl *D) {
   dumpName(D);
   dumpType(D->getType());

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -424,8 +424,6 @@ namespace clang {
     template<typename T>
     void mergeMergeable(Mergeable<T> *D);
 
-    void mergeMergeable(LifetimeExtendedTemporaryDecl *D);
-
     void mergeTemplatePattern(RedeclarableTemplateDecl *D,
                               RedeclarableTemplateDecl *Existing,
                               DeclID DsID, bool IsKeyDecl);
@@ -2360,7 +2358,6 @@ void ASTDeclReader::VisitLifetimeExtendedTemporaryDecl(
   if (Record.readInt())
     D->Value = new (D->getASTContext()) APValue(Record.readAPValue());
   D->ManglingNumber = Record.readInt();
-  mergeMergeable(D);
 }
 
 std::pair<uint64_t, uint64_t>
@@ -2558,25 +2555,6 @@ static bool allowODRLikeMergeInC(NamedDecl *ND) {
   return false;
 }
 
-/// Attempts to merge LifetimeExtendedTemporaryDecl with
-/// identical class definitions from two different modules.
-void ASTDeclReader::mergeMergeable(LifetimeExtendedTemporaryDecl *D) {
-  // If modules are not available, there is no reason to perform this merge.
-  if (!Reader.getContext().getLangOpts().Modules)
-    return;
-
-  LifetimeExtendedTemporaryDecl *LETDecl = D;
-
-  LifetimeExtendedTemporaryDecl *&LookupResult =
-      Reader.LETemporaryForMerging[std::make_pair(
-          LETDecl->getExtendingDecl(), LETDecl->getManglingNumber())];
-  if (LookupResult)
-    Reader.getContext().setPrimaryMergedDecl(LETDecl,
-                                             LookupResult->getCanonicalDecl());
-  else
-    LookupResult = LETDecl;
-}
-
 /// Attempts to merge the given declaration (D) with another declaration
 /// of the same entity, for the case where the entity is not actually
 /// redeclarable. This happens, for instance, when merging the fields of