Fix use-after-free found by address-san on -r322028.

r322028 attempted to remove something from the "Manglings"
list when it was no longer valid, and did so with 'erase'.

However, StringRefs to these were stored, so these became
dangling references.  This patch changes to using 'remove' instead
of 'erase' to keep the strings valid.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@322052 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CodeGenModule.cpp

@@ -813,7 +813,11 @@ void CodeGenModule::UpdateMultiVersionNames(GlobalDecl GD,
     // This is so that if the initial version was already the 'default'
     // version, we don't try to update it.
     if (OtherName != NonTargetName) {
-      Manglings.erase(NonTargetName);
+      // Remove instead of erase, since others may have stored the StringRef
+      // to this.
+      const auto ExistingRecord = Manglings.find(NonTargetName);
+      if (ExistingRecord != std::end(Manglings))
+        Manglings.remove(&(*ExistingRecord));
       auto Result = Manglings.insert(std::make_pair(OtherName, OtherGD));
       MangledDeclNames[OtherGD.getCanonicalDecl()] = Result.first->first();
       if (llvm::GlobalValue *Entry = GetGlobalValue(NonTargetName))