[modules] When we merge redecl chains or mark a decl used with an update

record, mark all subsequent decls as 'used' too, to maintain the AST invariant
that getPreviousDecl()->Used implies this->Used.

llvm-svn: 211050

1 files changed, 4 insertions, 1 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index e8db122445e..0c9f263faf1 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -8088,7 +8088,10 @@ void ASTReader::finishPendingActions() {
     }
 
     // Perform any pending declaration updates.
-    while (!PendingUpdateRecords.empty()) {
+    //
+    // Don't do this if we have known-incomplete redecl chains: it relies on
+    // being able to walk redeclaration chains.
+    while (PendingDeclChains.empty() && !PendingUpdateRecords.empty()) {
       auto Update = PendingUpdateRecords.pop_back_val();
       ReadingKindTracker ReadingKind(Read_Decl, *this);
       loadDeclUpdateRecords(Update.first, Update.second);