[ARC][ObjC++] Use ObjC semantic rules for comparisons between a pointer and

an ObjC object pointer

When ARC is enabled in Objective-C++, comparisons between a pointer and
Objective-C object pointer typically result in errors like this:
"invalid operands to a binary expression". This error message can be quite
confusing as it doesn't provide a solution to the problem, unlike the non-C++
diagnostic: "implicit conversion of Objective-C pointer type 'id' to C pointer
type 'void *' requires a bridged cast" (it also provides fix-its). This commit
forces comparisons between pointers and Objective-C object pointers in ARC to
use the Objective-C semantic rules to ensure that a better diagnostic is
reported.

rdar://31103857

Differential Revision: https://reviews.llvm.org/D31177

llvm-svn: 299080

1 files changed, 4 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 6144b5ac457..62863c25ebd 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -9423,7 +9423,10 @@ QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
     //   If both operands are pointers, [...] bring them to their composite
     //   pointer type.
     if ((int)LHSType->isPointerType() + (int)RHSType->isPointerType() >=
-        (IsRelational ? 2 : 1)) {
+            (IsRelational ? 2 : 1) &&
+        (!LangOpts.ObjCAutoRefCount ||
+         !(LHSType->isObjCObjectPointerType() ||
+           RHSType->isObjCObjectPointerType()))) {
       if (convertPointersToCompositeType(*this, Loc, LHS, RHS))
         return QualType();
       else