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.

llvm-svn: 94968
diff --git a/clang/lib/Frontend/PCHReader.cpp b/clang/lib/Frontend/PCHReader.cpp
index 2593551..bd93cf6 100644
--- a/clang/lib/Frontend/PCHReader.cpp
+++ b/clang/lib/Frontend/PCHReader.cpp
@@ -2464,11 +2464,10 @@
   PreloadedDecls.clear();
 
   // If there were any tentative definitions, deserialize them and add
-  // them to Sema's table of tentative definitions.
+  // them to Sema's list of tentative definitions.
   for (unsigned I = 0, N = TentativeDefinitions.size(); I != N; ++I) {
     VarDecl *Var = cast<VarDecl>(GetDecl(TentativeDefinitions[I]));
-    SemaObj->TentativeDefinitions[Var->getDeclName()] = Var;
-    SemaObj->TentativeDefinitionList.push_back(Var->getDeclName());
+    SemaObj->TentativeDefinitions.push_back(Var);
   }
 
   // If there were any locally-scoped external declarations,