Drop ObjCIndirectCopyRestoreExprs during template instantiation.

It's a kind of implicit conversion, which we generally drop, but
more importantly it's got very specific placement requirements.

rdar://13617051

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179254 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 27 insertions, 10 deletions

diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index 835609585e..81e02f5596 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -8608,16 +8608,11 @@ TreeTransform<Derived>::TransformObjCEncodeExpr(ObjCEncodeExpr *E) {
 template<typename Derived>
 ExprResult TreeTransform<Derived>::
 TransformObjCIndirectCopyRestoreExpr(ObjCIndirectCopyRestoreExpr *E) {
-  ExprResult result = getDerived().TransformExpr(E->getSubExpr());
-  if (result.isInvalid()) return ExprError();
-  Expr *subExpr = result.take();
-
-  if (!getDerived().AlwaysRebuild() &&
-      subExpr == E->getSubExpr())
-    return SemaRef.Owned(E);
-
-  return SemaRef.Owned(new(SemaRef.Context)
-      ObjCIndirectCopyRestoreExpr(subExpr, E->getType(), E->shouldCopy()));
+  // This is a kind of implicit conversion, and it needs to get dropped
+  // and recomputed for the same general reasons that ImplicitCastExprs
+  // do, as well a more specific one: this expression is only valid when
+  // it appears *immediately* as an argument expression.
+  return getDerived().TransformExpr(E->getSubExpr());
 }
 
 template<typename Derived>
diff --git a/test/CodeGenObjCXX/arc.mm b/test/CodeGenObjCXX/arc.mm
index 1888dbe77d..e3e86a0b0d 100644
--- a/test/CodeGenObjCXX/arc.mm
+++ b/test/CodeGenObjCXX/arc.mm
@@ -275,3 +275,25 @@ id Test39::bar() { return 0; }
 // CHECK:    define i8* @_ZThn8_N6Test393barEv(
 // CHECK:      call i8* @_ZN6Test393barEv(
 // CHECK-NEXT: ret i8*
+
+// rdar://13617051
+// Just a basic sanity-check that IR-gen still works after instantiating
+// a non-dependent message send that requires writeback.
+@interface Test40
++ (void) foo:(id *)errorPtr;
+@end
+template <class T> void test40_helper() {
+  id x;
+  [Test40 foo: &x];
+};
+template void test40_helper<int>();
+// CHECK:    define weak_odr void @_Z13test40_helperIiEvv()
+// CHECK:      [[X:%.*]] = alloca i8*
+// CHECK-NEXT: [[TEMP:%.*]] = alloca i8*
+// CHECK-NEXT: store i8* null, i8** [[X]]
+// CHECK:      [[T0:%.*]] = load i8** [[X]]
+// CHECK-NEXT: store i8* [[T0]], i8** [[TEMP]]
+// CHECK:      @objc_msgSend
+// CHECK-NEXT: [[T0:%.*]] = load i8** [[TEMP]]
+// CHECK-NEXT: call i8* @objc_retain(i8* [[T0]])
+