[modules] Teach the ASTWriter to ignore mutations coming from the ASTReader.

Processing update records (and loading a module, in general) might trigger
unexpected calls to the ASTWriter (being a mutation listener). Now we have a
mechanism to suppress those calls to the ASTWriter but notify other possible
mutation listeners.

Fixes https://llvm.org/bugs/show_bug.cgi?id=28332

Patch by Cristina Cristescu and me.

Reviewed by Richard Smith (D21800).

llvm-svn: 276473

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 6bfae07b82b..27b7048f375 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -8644,6 +8644,7 @@ void ASTReader::FinishedDeserializing() {
       auto Updates = std::move(PendingExceptionSpecUpdates);
       PendingExceptionSpecUpdates.clear();
       for (auto Update : Updates) {
+        ProcessingUpdatesRAIIObj ProcessingUpdates(*this);
         auto *FPT = Update.second->getType()->castAs<FunctionProtoType>();
         auto ESI = FPT->getExtProtoInfo().ExceptionSpec;
         if (auto *Listener = Context.getASTMutationListener())
@@ -8714,6 +8715,7 @@ ASTReader::ASTReader(
       AllowConfigurationMismatch(AllowConfigurationMismatch),
       ValidateSystemInputs(ValidateSystemInputs),
       UseGlobalIndex(UseGlobalIndex), TriedLoadingGlobalIndex(false),
+      ProcessingUpdateRecords(false),
       CurrSwitchCaseStmts(&SwitchCaseStmts), NumSLocEntriesRead(0),
       TotalNumSLocEntries(0), NumStatementsRead(0), TotalNumStatements(0),
       NumMacrosRead(0), TotalNumMacros(0), NumIdentifierLookups(0),