[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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@163220 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 3 deletions

diff --git a/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp b/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
index 84001d3a0c..d3d2837fe5 100644
--- a/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngineCXX.cpp
@@ -34,9 +34,10 @@ void ExprEngine::CreateCXXTemporaryObject(const MaterializeTemporaryExpr *ME,
   // the expression to the location of the object.
   SVal V = state->getSVal(tempExpr, LCtx);
 
-  // If the object is a record, the constructor will have already created
-  // a temporary object region. If it is not, we need to copy the value over.
-  if (!ME->getType()->isRecordType()) {
+  // If the value is already a CXXTempObjectRegion, it is fine as it is.
+  // Otherwise, create a new CXXTempObjectRegion, and copy the value into it.
+  const MemRegion *MR = V.getAsRegion();
+  if (!MR || !isa<CXXTempObjectRegion>(MR)) {
     const MemRegion *R =
       svalBuilder.getRegionManager().getCXXTempObjectRegion(ME, LCtx);