From 04b6584405d0d5552c23babecfc2dd664bf93ee1 Mon Sep 17 00:00:00 2001
From: John McCall <rjmccall@apple.com>
Date: Sat, 7 Apr 2018 17:42:06 +0000
Subject: [PATCH] Allow equality comparisons between block pointers and
 block-pointer-compatible ObjC object pointer types.

Patch by Dustin Howett!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@329508 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaExpr.cpp          | 13 +++++++++
 test/SemaObjC/block-compare.mm | 51 ++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 test/SemaObjC/block-compare.mm

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 71cbd7f777..b8cadaf7ab 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -10029,6 +10029,19 @@ QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
         RHS = ImpCastExprToType(RHS.get(), LHSType, CK_BitCast);
       return ResultTy;
     }
+
+    if (!IsRelational && LHSType->isBlockPointerType() &&
+        RHSType->isBlockCompatibleObjCPointerType(Context)) {
+      LHS = ImpCastExprToType(LHS.get(), RHSType,
+                              CK_BlockPointerToObjCPointerCast);
+      return ResultTy;
+    } else if (!IsRelational &&
+               LHSType->isBlockCompatibleObjCPointerType(Context) &&
+               RHSType->isBlockPointerType()) {
+      RHS = ImpCastExprToType(RHS.get(), LHSType,
+                              CK_BlockPointerToObjCPointerCast);
+      return ResultTy;
+    }
   }
   if ((LHSType->isAnyPointerType() && RHSType->isIntegerType()) ||
       (LHSType->isIntegerType() && RHSType->isAnyPointerType())) {
diff --git a/test/SemaObjC/block-compare.mm b/test/SemaObjC/block-compare.mm
new file mode 100644
index 0000000000..c63f484a80
--- /dev/null
+++ b/test/SemaObjC/block-compare.mm
@@ -0,0 +1,51 @@
+// RUN: %clang_cc1 -S -o - -triple i686-windows -verify -fblocks \
+// RUN:     -Wno-unused-comparison %s
+
+#pragma clang diagnostic ignored "-Wunused-comparison"
+
+#define nil ((id)nullptr)
+
+@protocol NSObject
+@end
+
+@protocol NSCopying
+@end
+
+@protocol OtherProtocol
+@end
+
+__attribute__((objc_root_class))
+@interface NSObject <NSObject, NSCopying>
+@end
+
+__attribute__((objc_root_class))
+@interface Test
+@end
+
+int main() {
+  void (^block)() = ^{};
+  NSObject *object;
+  id<NSObject, NSCopying> qualifiedId;
+
+  id<OtherProtocol> poorlyQualified1;
+  Test *objectOfWrongType;
+
+  block == nil;
+  block == object;
+  block == qualifiedId;
+
+  nil == block;
+  object == block;
+  qualifiedId == block;
+
+  // these are still not valid: blocks must be compared with id, NSObject*, or a protocol-qualified id
+  // conforming to NSCopying or NSObject.
+
+  block == poorlyQualified1; // expected-error {{invalid operands to binary expression ('void (^)()' and 'id<OtherProtocol>')}}
+  block == objectOfWrongType; // expected-error {{invalid operands to binary expression ('void (^)()' and 'Test *')}}
+
+  poorlyQualified1 == block; // expected-error {{invalid operands to binary expression ('id<OtherProtocol>' and 'void (^)()')}}
+  objectOfWrongType == block; // expected-error {{invalid operands to binary expression ('Test *' and 'void (^)()')}}
+
+  return 0;
+}
-- 
2.40.0