Add VarDecl::isThisDeclarationADefinition(), which properly encapsulates the logic for when a variable declaration is a (possibly tentativ) definition. Add a few functions building on this, and shift C tentative definition handling over to this new functionality. This shift also kills the Sema::TentativeDefinitions map and instead simply stores all declarations in the renamed list. The correct handling for multiple tentative definitions is instead shifted to the final walk of the list.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94968 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 9909c95..caf1ce4 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -1960,13 +1960,11 @@
   }
 
   // Build a record containing all of the tentative definitions in this file, in
-  // TentativeDefinitionList order.  Generally, this record will be empty for
+  // TentativeDefinitions order.  Generally, this record will be empty for
   // headers.
   RecordData TentativeDefinitions;
-  for (unsigned i = 0, e = SemaRef.TentativeDefinitionList.size(); i != e; ++i){
-    VarDecl *VD =
-      SemaRef.TentativeDefinitions.lookup(SemaRef.TentativeDefinitionList[i]);
-    if (VD) AddDeclRef(VD, TentativeDefinitions);
+  for (unsigned i = 0, e = SemaRef.TentativeDefinitions.size(); i != e; ++i) {
+    AddDeclRef(SemaRef.TentativeDefinitions[i], TentativeDefinitions);
   }
 
   // Build a record containing all of the locally-scoped external