[analyzer] Create a temporary region for rvalue structs when accessing fields

Struct rvalues are represented in the analyzer by CompoundVals,
LazyCompoundVals, or plain ConjuredSymbols -- none of which have associated
regions. If the entire structure is going to persist, this is not a
problem -- either the rvalue will be assigned to an existing region, or
a MaterializeTemporaryExpr will be present to create a temporary region.
However, if we just need a field from the struct, we need to create the
temporary region ourselves.

This is inspired by the way CodeGen handles calls to temporaries;
support for that in the analyzer is coming next.

Part of <rdar://problem/12137950>

llvm-svn: 164828

1 files changed, 1 insertions, 3 deletions

diff --git a/clang/test/Analysis/reference.cpp b/clang/test/Analysis/reference.cpp
index 374f3f7261c..ce0ee8ed57d 100644
--- a/clang/test/Analysis/reference.cpp
+++ b/clang/test/Analysis/reference.cpp
@@ -116,10 +116,8 @@ void testReferenceAddress(int &x) {
 
   struct S { int &x; };
 
-  // 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}}
+  clang_analyzer_eval(&getS().x != 0); // expected-warning{{TRUE}}
 
   extern S *getSP();
   clang_analyzer_eval(&getSP()->x != 0); // expected-warning{{TRUE}}