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

This reverts commit 3c7f6b4396.

clang/include/clang/AST/DeclCXX.h

@@ -3041,9 +3041,7 @@ public:
 
 /// 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 @@ public:
   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 @@ private:
   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

@@ -424,9 +424,6 @@ namespace clang {
     template<typename T>
     void mergeMergeable(Mergeable<T> *D);
 
-    template <>
-    void mergeMergeable(Mergeable<LifetimeExtendedTemporaryDecl> *D);
-
     void mergeTemplatePattern(RedeclarableTemplateDecl *D,
                               RedeclarableTemplateDecl *Existing,
                               DeclID DsID, bool IsKeyDecl);
@@ -2361,7 +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>
@@ -2559,28 +2555,6 @@ static bool allowODRLikeMergeInC(NamedDecl *ND) {
   return false;
 }
 
-/// Attempts to merge LifetimeExtendedTemporaryDecl with
-/// identical class definitions from two different modules.
-template<>
-void ASTDeclReader::mergeMergeable(
-    Mergeable<LifetimeExtendedTemporaryDecl> *D) {
-  // If modules are not available, there is no reason to perform this merge.
-  if (!Reader.getContext().getLangOpts().Modules)
-    return;
-
-  LifetimeExtendedTemporaryDecl *LETDecl =
-      static_cast<LifetimeExtendedTemporaryDecl *>(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

clang/test/Modules/Inputs/merge-lifetime-extended-temporary/a.h

@@ -1,2 +0,0 @@
-
-constexpr const int& LETemp = 0;

clang/test/Modules/Inputs/merge-lifetime-extended-temporary/b.h

@@ -1,4 +0,0 @@
-
-#include "a.h"
-
-constexpr const int* PtrTemp1 = &LETemp;

clang/test/Modules/Inputs/merge-lifetime-extended-temporary/c.h

@@ -1,4 +0,0 @@
-
-#include "a.h"
-
-constexpr const int* PtrTemp2 = &LETemp;

clang/test/Modules/Inputs/merge-lifetime-extended-temporary/module.modulemap

@@ -1,14 +0,0 @@
-module "a" {
-  export *
-  header "a.h"
-}
-
-module "b" {
-  export *
-  header "b.h"
-}
-
-module "c" {
-  export *
-  header "c.h"
-}

clang/test/Modules/merge-lifetime-extended-temporary.cpp

@@ -1,14 +0,0 @@
-// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -x c++ -I%S/Inputs/merge-lifetime-extended-temporary -verify -std=c++11 %s -DORDER=1
-// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -x c++ -I%S/Inputs/merge-lifetime-extended-temporary -verify -std=c++11 %s -DORDER=2
-
-// expected-no-diagnostics
-#if ORDER == 1
-#include "c.h"
-#include "b.h"
-#else
-#include "b.h"
-#include "c.h"
-#endif
-
-static_assert(PtrTemp1 == &LETemp, "");
-static_assert(PtrTemp1 == PtrTemp2, "");