[ObjC] Fix type checking for qualified id block parameters.

When checking if block types are compatible, we are checking for
compatibility their return types and parameters' types. As these types
have different variance, we need to check them in different order.

rdar://problem/52788423

Reviewers: erik.pilkington, arphaman

Reviewed By: arphaman

Subscribers: jkorous, dexonsmith, ributzka, cfe-commits

Differential Revision: https://reviews.llvm.org/D66831



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@370130 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/ASTContext.cpp

@@ -8191,9 +8191,9 @@ bool ASTContext::canAssignObjCInterfacesInBlockPointer(
   }
 
   if (LHSOPT->isObjCQualifiedIdType() || RHSOPT->isObjCQualifiedIdType())
-    return finish(ObjCQualifiedIdTypesAreCompatible(QualType(LHSOPT,0),
-                                                    QualType(RHSOPT,0),
-                                                    false));
+    return finish(ObjCQualifiedIdTypesAreCompatible(
+        QualType(BlockReturnType ? LHSOPT : RHSOPT, 0),
+        QualType(BlockReturnType ? RHSOPT : LHSOPT, 0), false));
 
   const ObjCInterfaceType* LHS = LHSOPT->getInterfaceType();
   const ObjCInterfaceType* RHS = RHSOPT->getInterfaceType();

test/SemaObjC/block-type-safety.m

@@ -133,9 +133,20 @@ int test4 () {
 @end
 
 int test5() {
+    // Returned value is used outside of a block, so error on changing
+    // a return type to a more general than expected.
     NSAllArray *(^block)(id);
     id <Foo> (^genericBlock)(id);
     genericBlock = block;
+    block = genericBlock; // expected-error {{incompatible block pointer types assigning to 'NSAllArray *(^)(id)' from 'id<Foo> (^)(id)'}}
+
+    // A parameter is used inside a block, so error on changing a parameter type
+    // to a more specific than an argument type it will be called with.
+    // rdar://problem/52788423
+    void (^blockWithParam)(NSAllArray *);
+    void (^genericBlockWithParam)(id<Foo>);
+    genericBlockWithParam = blockWithParam; // expected-error {{incompatible block pointer types assigning to 'void (^)(id<Foo>)' from 'void (^)(NSAllArray *)'}}
+    blockWithParam = genericBlockWithParam;
     return 0;
 }