[analyzer] Be more forgiving about calling methods on struct rvalues.

The problem is that the value of 'this' in a C++ member function call
should always be a region (or NULL). However, if the object is an rvalue,
it has no associated region (only a conjured symbol or LazyCompoundVal).
For now, we handle this in two ways:

1) Actually respect MaterializeTemporaryExpr. Before, it was relying on
   CXXConstructExpr to create temporary regions for all struct values.
   Now it just does the right thing: if the value is not in a temporary
   region, create one.

2) Have CallEvent recognize the case where its 'this' pointer is a
   non-region, and just return UnknownVal to keep from confusing clients.

The long-term problem is being tracked internally in <rdar://problem/12137950>,
but this makes many test cases pass.

llvm-svn: 163220

1 files changed, 7 insertions, 9 deletions

diff --git a/clang/test/Analysis/reference.cpp b/clang/test/Analysis/reference.cpp
index 4a2cbb8..374f3f7 100644
--- a/clang/test/Analysis/reference.cpp
+++ b/clang/test/Analysis/reference.cpp
@@ -116,8 +116,13 @@ void testReferenceAddress(int &x) {
 
   struct S { int &x; };
 
-  extern S *getS();
-  clang_analyzer_eval(&getS()->x != 0); // expected-warning{{TRUE}}
+  // FIXME: Should be TRUE. Fields of return-by-value structs are not yet
+  // symbolicated. Tracked by <rdar://problem/12137950>.
+  extern S getS();
+  clang_analyzer_eval(&getS().x != 0); // expected-warning{{UNKNOWN}}
+
+  extern S *getSP();
+  clang_analyzer_eval(&getSP()->x != 0); // expected-warning{{TRUE}}
 }
 
 
@@ -150,10 +155,3 @@ namespace rdar11212286 {
     return *x; // should warn here!
   }
 }
-
-void testReferenceFieldAddress() {
-  struct S { int &x; };
-
-  extern S getS();
-  clang_analyzer_eval(&getS().x != 0); // expected-warning{{UNKNOWN}}
-}