Reapply "[analyzer] Treat fields of unions as having symbolic offsets."

This time, actually uncomment the code that's supposed to fix the problem.

This reverts r165671 / 8ceb837585ed973dc36fba8dfc57ef60fc8f2735.

llvm-svn: 165676

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
index 7c66739558a..fab10cfd3d0 100644
--- a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -1168,8 +1168,12 @@ RegionOffset MemRegion::getAsOffset() const {
       R = FR->getSuperRegion();
 
       const RecordDecl *RD = FR->getDecl()->getParent();
-      if (!RD->isCompleteDefinition()) {
+      if (RD->isUnion() || !RD->isCompleteDefinition()) {
         // We cannot compute offset for incomplete type.
+        // For unions, we could treat everything as offset 0, but we'd rather
+        // treat each field as a symbolic offset so they aren't stored on top
+        // of each other, since we depend on things in typed regions actually
+        // matching their types.
         SymbolicOffsetBase = R;
       }