Add a FIXME for mutation of the common pointer of a RedeclarableTemplateDecl. It is not clear that it's worth delaying the allocation of said pointer

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148182 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 32432c0..bf2200d 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -1237,9 +1237,11 @@
 
 template <typename T>
 void ASTDeclWriter::VisitRedeclarable(Redeclarable<T> *D) {
+  T *First = D->getFirstDeclaration();
+  Writer.AddDeclRef(First);
+  
   enum { FirstDeclaration = 0, FirstInFile, PointsToPrevious };
   T *Prev = D->getPreviousDeclaration();
-  T *First = D->getFirstDeclaration();
   
   if (!Prev) {
     Record.push_back(FirstDeclaration);