1 files changed, 43 insertions, 35 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 78c44d17887..930b651f9ef 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3316,16 +3316,6 @@ ASTReader::ReadASTBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
       break;
     }
         
-    case MERGED_DECLARATIONS: {
-      for (unsigned Idx = 0; Idx < Record.size(); /* increment in loop */) {
-        GlobalDeclID CanonID = getGlobalDeclID(F, Record[Idx++]);
-        SmallVectorImpl<GlobalDeclID> &Decls = StoredMergedDecls[CanonID];
-        for (unsigned N = Record[Idx++]; N > 0; --N)
-          Decls.push_back(getGlobalDeclID(F, Record[Idx++]));
-      }
-      break;
-    }
-
     case MACRO_OFFSET: {
       if (F.LocalNumMacros != 0) {
         Error("duplicate MACRO_OFFSET record in AST file");
@@ -6227,6 +6217,10 @@ ASTReader::getGlobalDeclID(ModuleFile &F, LocalDeclID LocalID) const {
 
 bool ASTReader::isDeclIDFromModule(serialization::GlobalDeclID ID,
                                    ModuleFile &M) const {
+  // Predefined decls aren't from any module.
+  if (ID < NUM_PREDEF_DECL_IDS)
+    return false;
+
   GlobalDeclMapType::const_iterator I = GlobalDeclMap.find(ID);
   assert(I != GlobalDeclMap.end() && "Corrupted global declaration map");
   return &M == I->second;
@@ -6259,39 +6253,51 @@ SourceLocation ASTReader::getSourceLocationForDeclID(GlobalDeclID ID) {
   return ReadSourceLocation(*Rec.F, RawLocation);
 }
 
-Decl *ASTReader::GetExistingDecl(DeclID ID) {
-  if (ID < NUM_PREDEF_DECL_IDS) {
-    switch ((PredefinedDeclIDs)ID) {
-    case PREDEF_DECL_NULL_ID:
-      return nullptr;
+static Decl *getPredefinedDecl(ASTContext &Context, PredefinedDeclIDs ID) {
+  switch (ID) {
+  case PREDEF_DECL_NULL_ID:
+    return nullptr;
 
-    case PREDEF_DECL_TRANSLATION_UNIT_ID:
-      return Context.getTranslationUnitDecl();
+  case PREDEF_DECL_TRANSLATION_UNIT_ID:
+    return Context.getTranslationUnitDecl();
 
-    case PREDEF_DECL_OBJC_ID_ID:
-      return Context.getObjCIdDecl();
+  case PREDEF_DECL_OBJC_ID_ID:
+    return Context.getObjCIdDecl();
 
-    case PREDEF_DECL_OBJC_SEL_ID:
-      return Context.getObjCSelDecl();
+  case PREDEF_DECL_OBJC_SEL_ID:
+    return Context.getObjCSelDecl();
 
-    case PREDEF_DECL_OBJC_CLASS_ID:
-      return Context.getObjCClassDecl();
+  case PREDEF_DECL_OBJC_CLASS_ID:
+    return Context.getObjCClassDecl();
 
-    case PREDEF_DECL_OBJC_PROTOCOL_ID:
-      return Context.getObjCProtocolDecl();
+  case PREDEF_DECL_OBJC_PROTOCOL_ID:
+    return Context.getObjCProtocolDecl();
 
-    case PREDEF_DECL_INT_128_ID:
-      return Context.getInt128Decl();
+  case PREDEF_DECL_INT_128_ID:
+    return Context.getInt128Decl();
 
-    case PREDEF_DECL_UNSIGNED_INT_128_ID:
-      return Context.getUInt128Decl();
+  case PREDEF_DECL_UNSIGNED_INT_128_ID:
+    return Context.getUInt128Decl();
 
-    case PREDEF_DECL_OBJC_INSTANCETYPE_ID:
-      return Context.getObjCInstanceTypeDecl();
+  case PREDEF_DECL_OBJC_INSTANCETYPE_ID:
+    return Context.getObjCInstanceTypeDecl();
+
+  case PREDEF_DECL_BUILTIN_VA_LIST_ID:
+    return Context.getBuiltinVaListDecl();
+  }
+}
 
-    case PREDEF_DECL_BUILTIN_VA_LIST_ID:
-      return Context.getBuiltinVaListDecl();
+Decl *ASTReader::GetExistingDecl(DeclID ID) {
+  if (ID < NUM_PREDEF_DECL_IDS) {
+    Decl *D = getPredefinedDecl(Context, (PredefinedDeclIDs)ID);
+    if (D) {
+      // Track that we have merged the declaration with ID \p ID into the
+      // pre-existing predefined declaration \p D.
+      auto &Merged = MergedDecls[D->getCanonicalDecl()];
+      if (Merged.empty())
+        Merged.push_back(ID);
     }
+    return D;
   }
 
   unsigned Index = ID - NUM_PREDEF_DECL_IDS;
@@ -8302,9 +8308,11 @@ void ASTReader::finishPendingActions() {
     PendingIncompleteDeclChains.clear();
 
     // Load pending declaration chains.
-    for (unsigned I = 0; I != PendingDeclChains.size(); ++I)
+    for (unsigned I = 0; I != PendingDeclChains.size(); ++I) {
       loadPendingDeclChain(PendingDeclChains[I]);
-    PendingDeclChainsKnown.clear();
+      PendingDeclChainsKnown.erase(PendingDeclChains[I]);
+    }
+    assert(PendingDeclChainsKnown.empty());
     PendingDeclChains.clear();
 
     // Make the most recent of the top-level declarations visible.