Reapply 112850 and 112839 with a constructor for the BinaryOperatorData struct. Clang would zero out the enum and pointer in the struct in some conditions, but GCC would never zero out the values.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112909 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/BugReporterVisitors.cpp b/lib/Checker/BugReporterVisitors.cpp
index cddc86e..91cf349 100644
--- a/lib/Checker/BugReporterVisitors.cpp
+++ b/lib/Checker/BugReporterVisitors.cpp
@@ -419,3 +419,40 @@
 void clang::bugreporter::registerNilReceiverVisitor(BugReporterContext &BRC) {
   BRC.addVisitor(new NilReceiverVisitor());
 }
+
+// Registers every VarDecl inside a Stmt with a last store vistor.
+void clang::bugreporter::registerVarDeclsLastStore(BugReporterContext &BRC,
+                                                   const void *stmt,
+                                                   const ExplodedNode *N) {
+  const Stmt *S = static_cast<const Stmt *>(stmt);
+
+  std::deque<const Stmt *> WorkList;
+
+  WorkList.push_back(S);
+
+  while (!WorkList.empty()) {
+    const Stmt *Head = WorkList.front();
+    WorkList.pop_front();
+
+    GRStateManager &StateMgr = BRC.getStateManager();
+    const GRState *state = N->getState();
+
+    if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Head)) {
+      if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
+        const VarRegion *R =
+        StateMgr.getRegionManager().getVarRegion(VD, N->getLocationContext());
+
+        // What did we load?
+        SVal V = state->getSVal(S);
+
+        if (isa<loc::ConcreteInt>(V) || isa<nonloc::ConcreteInt>(V)) {
+          ::registerFindLastStore(BRC, R, V);
+        }
+      }
+    }
+
+    for (Stmt::const_child_iterator I = Head->child_begin();
+        I != Head->child_end(); ++I)
+      WorkList.push_back(*I);
+  }
+}