We can't emit an aggregate cast as its sub-expression in general just

because the result is ignored.  The particular example here is with
property l-values, but there could be all sorts of lovely casts that this
isn't safe for.  Sink the check into the one case that seems to actually
be capable of honoring this.

llvm-svn: 129397

2 files changed, 9 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 177d0a4be78..4315915c166 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -249,11 +249,6 @@ void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
 }
 
 void AggExprEmitter::VisitCastExpr(CastExpr *E) {
-  if (Dest.isIgnored() && E->getCastKind() != CK_Dynamic) {
-    Visit(E->getSubExpr());
-    return;
-  }
-
   switch (E->getCastKind()) {
   case CK_Dynamic: {
     assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
@@ -270,6 +265,8 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
   }
       
   case CK_ToUnion: {
+    if (Dest.isIgnored()) break;
+
     // GCC union extension
     QualType Ty = E->getSubExpr()->getType();
     QualType PtrTy = CGF.getContext().getPointerType(Ty);
diff --git a/clang/test/CodeGenObjC/property-agrr-getter.m b/clang/test/CodeGenObjC/property-agrr-getter.m
index 2dd32bb4f37..6d8f1d6b03a 100644
--- a/clang/test/CodeGenObjC/property-agrr-getter.m
+++ b/clang/test/CodeGenObjC/property-agrr-getter.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm -o %t %s
+// RUN: %clang_cc1 -emit-llvm-only %s
 
 typedef struct {
   unsigned f0;
@@ -36,3 +36,9 @@ float f ()
   AnObject* obj;
   return (obj.size).width;
 }
+
+// rdar://problem/9272392
+void test3(AnObject *obj) {
+  obj.size;
+  (void) obj.size;
+}