[PATCH] D44580: Sema: allow comparison between blocks & block-compatible objc types

[Dustin L. Howett via Phabricator via cfe-commits]

DHowett-MSFT created this revision.
DHowett-MSFT added reviewers: theraven, rjmccall.
DHowett-MSFT added a project: clang.
Herald added a subscriber: cfe-commits.

This commit makes valid the following code:

  // objective-c++
  #define nil ((id)nullptr)
  ...
  void (^f)() = ^{};
  if (f == nil) {
  }
  …

Where it would previously fail with the error `invalid operands to binary expression ('void (^)()' and 'id')`.

Comparisons are now allowed between block types and `id`, `id<NSCopying>`, `id<NSObject>`, and `NSObject*`. No other comparisons are changed.


Repository:
  rC Clang

https://reviews.llvm.org/D44580

Files:
  lib/Sema/SemaExpr.cpp
  test/Sema/objc_block_compare.mm


Index: test/Sema/objc_block_compare.mm
===================================================================
--- /dev/null
+++ test/Sema/objc_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)
+
+ at protocol NSObject
+ at end
+
+ at protocol NSCopying
+ at end
+
+ at protocol OtherProtocol
+ at end
+
+__attribute__((objc_root_class))
+ at interface NSObject <NSObject, NSCopying>
+ at end
+
+__attribute__((objc_root_class))
+ at interface Test
+ at 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;
+}
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -7745,8 +7745,8 @@
       return IntToBlockPointer;
     }
 
-    // id -> T^
-    if (getLangOpts().ObjC1 && RHSType->isObjCIdType()) {
+    // id (or strictly compatible object type) -> T^
+    if (getLangOpts().ObjC1 && RHSType->isBlockCompatibleObjCPointerType(Context)) {
       Kind = CK_AnyPointerToBlockPointerCast;
       return Compatible;
     }
@@ -10028,6 +10028,18 @@
         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())) {


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