1 files changed, 23 insertions, 3 deletions
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index a00d40659f..53fa21f9aa 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -457,6 +457,16 @@ ASTIdentifierLookupTraitBase::ReadKey(const unsigned char* d, unsigned n) {
   return StringRef((const char*) d, n-1);
 }
 
+/// \brief Whether the given identifier is "interesting".
+static bool isInterestingIdentifier(IdentifierInfo &II) {
+  return II.isPoisoned() ||
+         II.isExtensionToken() ||
+         II.getObjCOrBuiltinID() ||
+         II.hasRevertedTokenIDToIdentifier() ||
+         II.hadMacroDefinition() ||
+         II.getFETokenInfo<void>();
+}
+
 IdentifierInfo *ASTIdentifierLookupTrait::ReadData(const internal_key_type& k,
                                                    const unsigned char* d,
                                                    unsigned DataLen) {
@@ -477,8 +487,13 @@ IdentifierInfo *ASTIdentifierLookupTrait::ReadData(const internal_key_type& k,
       KnownII = II;
     }
     Reader.SetIdentifierInfo(ID, II);
-    II->setIsFromAST();
-    Reader.markIdentifierUpToDate(II);    
+    if (!II->isFromAST()) {
+      bool WasInteresting = isInterestingIdentifier(*II);
+      II->setIsFromAST();
+      if (WasInteresting)
+        II->setChangedSinceDeserialization();
+    }
+    Reader.markIdentifierUpToDate(II);
     return II;
   }
 
@@ -506,7 +521,12 @@ IdentifierInfo *ASTIdentifierLookupTrait::ReadData(const internal_key_type& k,
     KnownII = II;
   }
   Reader.markIdentifierUpToDate(II);
-  II->setIsFromAST();
+  if (!II->isFromAST()) {
+    bool WasInteresting = isInterestingIdentifier(*II);
+    II->setIsFromAST();
+    if (WasInteresting)
+      II->setChangedSinceDeserialization();
+  }
 
   // Set or check the various bits in the IdentifierInfo structure.
   // Token IDs are read-only.