[analyzer] Tweak getDerefExpr more to track DeclRefExprs to references.

In the committed example, we now see a note that tells us when the pointer
was assumed to be null.

This is the only case in which getDerefExpr returned null (failed to get
the dereferenced expr) throughout our regression tests. (There were multiple
occurrences of this one.)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179736 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp b/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
index 9cf39d1e96..11fb1fcebd 100644
--- a/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
+++ b/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
@@ -41,7 +41,7 @@ bool bugreporter::isDeclRefExprToReference(const Expr *E) {
 }
 
 const Expr *bugreporter::getDerefExpr(const Stmt *S) {
-  // Pattern match for a few useful cases (do something smarter later):
+  // Pattern match for a few useful cases:
   //   a[0], p->f, *p
   const Expr *E = dyn_cast<Expr>(S);
   if (!E)
@@ -73,6 +73,9 @@ const Expr *bugreporter::getDerefExpr(const Stmt *S) {
     else if (const ArraySubscriptExpr *AE = dyn_cast<ArraySubscriptExpr>(E)) {
       return AE->getBase();
     }
+    else if (isDeclRefExprToReference(E)) {
+      return E;
+    }
     break;
   }