2 files changed, 41 insertions, 1 deletions
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index eb151ef16f6..f6d705af88c 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -5940,6 +5940,15 @@ Decl *ASTReader::GetExternalDecl(uint32_t ID) {
 }
 
 void ASTReader::CompleteRedeclChain(const Decl *D) {
+  if (NumCurrentElementsDeserializing) {
+    // We arrange to not care about the complete redeclaration chain while we're
+    // deserializing. Just remember that the AST has marked this one as complete
+    // but that it's not actually complete yet, so we know we still need to
+    // complete it later.
+    PendingIncompleteDeclChains.push_back(const_cast<Decl*>(D));
+    return;
+  }
+
   const DeclContext *DC = D->getDeclContext()->getRedeclContext();
 
   // Recursively ensure that the decl context itself is complete
@@ -7983,7 +7992,8 @@ std::string ASTReader::getOwningModuleNameForDiagnostic(const Decl *D) {
 }
 
 void ASTReader::finishPendingActions() {
-  while (!PendingIdentifierInfos.empty() || !PendingDeclChains.empty() ||
+  while (!PendingIdentifierInfos.empty() ||
+         !PendingIncompleteDeclChains.empty() || !PendingDeclChains.empty() ||
          !PendingMacroIDs.empty() || !PendingDeclContextInfos.empty() ||
          !PendingUpdateRecords.empty() || !PendingOdrMergeChecks.empty()) {
     // If any identifiers with corresponding top-level declarations have
@@ -8001,6 +8011,13 @@ void ASTReader::finishPendingActions() {
       SetGloballyVisibleDecls(II, DeclIDs, &TopLevelDecls[II]);
     }
 
+    // For each decl chain that we wanted to complete while deserializing, mark
+    // it as "still needs to be completed".
+    for (unsigned I = 0; I != PendingIncompleteDeclChains.size(); ++I) {
+      markIncompleteDeclChain(PendingIncompleteDeclChains[I]);
+    }
+    PendingIncompleteDeclChains.clear();
+
     // Load pending declaration chains.
     for (unsigned I = 0; I != PendingDeclChains.size(); ++I) {
       loadPendingDeclChain(PendingDeclChains[I]);
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 719d56edf2c..bb87632962e 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -208,6 +208,10 @@ namespace clang {
     static void attachLatestDeclImpl(...);
     static void attachLatestDecl(Decl *D, Decl *latest);
 
+    template <typename DeclT>
+    static void markIncompleteDeclChainImpl(Redeclarable<DeclT> *D);
+    static void markIncompleteDeclChainImpl(...);
+
     /// \brief Determine whether this declaration has a pending body.
     bool hasPendingBody() const { return HasPendingBody; }
 
@@ -2510,6 +2514,25 @@ void ASTDeclReader::attachLatestDecl(Decl *D, Decl *Latest) {
   }
 }
 
+template<typename DeclT>
+void ASTDeclReader::markIncompleteDeclChainImpl(Redeclarable<DeclT> *D) {
+  D->RedeclLink.markIncomplete();
+}
+void ASTDeclReader::markIncompleteDeclChainImpl(...) {
+  llvm_unreachable("markIncompleteDeclChain on non-redeclarable declaration");
+}
+
+void ASTReader::markIncompleteDeclChain(Decl *D) {
+  switch (D->getKind()) {
+#define ABSTRACT_DECL(TYPE)
+#define DECL(TYPE, BASE)                                             \
+  case Decl::TYPE:                                                   \
+    ASTDeclReader::markIncompleteDeclChainImpl(cast<TYPE##Decl>(D)); \
+    break;
+#include "clang/AST/DeclNodes.inc"
+  }
+}
+
 ASTReader::MergedDeclsMap::iterator
 ASTReader::combineStoredMergedDecls(Decl *Canon, GlobalDeclID CanonID) {
   // If we don't have any stored merged declarations, just look in the