Merge pull request #6296 from rudkx/disable-any-penalty

Do not penalize binding or equality constraints involving Any.

Author: rudkx

lib/Sema/CSRanking.cpp

@@ -74,9 +74,6 @@ void ConstraintSystem::increaseScore(ScoreKind kind) {
     case SK_ScalarPointerConversion:
       log << "scalar-to-pointer conversion";
       break;
-    case SK_EmptyExistentialConversion:
-      log << "empty-existential conversion";
-      break;
     }
     log << ")\n";
   }

lib/Sema/CSSimplify.cpp

@@ -1356,12 +1356,7 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
         }
 
         assignFixedType(typeVar1, type2);
-        
-        // For symmetry with overload resolution, penalize conversions to empty
-        // existentials.
-        if (type2->isAny())
-          increaseScore(ScoreKind::SK_EmptyExistentialConversion);
-        
+
         return SolutionKind::Solved;
       }
 

lib/Sema/ConstraintSystem.h

@@ -406,10 +406,8 @@ enum ScoreKind {
   SK_ScalarPointerConversion,
   /// A conversion from an array to a pointer of matching element type.
   SK_ArrayPointerConversion,
-  /// A conversion to an empty existential type ('Any' or '{}').
-  SK_EmptyExistentialConversion,
 
-  SK_LastScoreKind = SK_EmptyExistentialConversion,
+  SK_LastScoreKind = SK_ArrayPointerConversion,
 };
 
 /// The number of score kinds.

test/Constraints/Inputs/overload.h

@@ -0,0 +1,4 @@
+@interface Rdar29374163Itf
+@property (nonnull, readonly, retain) id foo;
+- (_Nonnull id) fooWithRdar29374163Itf:(Rdar29374163Itf * _Nonnull) rdar29374163itf;
+@end

test/Constraints/diag_ambiguities.swift

@@ -28,3 +28,10 @@ C(g) // expected-error{{ambiguous use of 'g'}}
 
 func h<T>(_ x: T) -> () {}
 C(h) // expected-error{{ambiguous use of 'init'}}
+
+func rdar29691909_callee(_ o: AnyObject?) -> Any? { return o } // expected-note {{found this candidate}}
+func rdar29691909_callee(_ o: AnyObject) -> Any { return o } // expected-note {{found this candidate}}
+
+func rdar29691909(o: AnyObject) -> Any? {
+  return rdar29691909_callee(o) // expected-error{{ambiguous use of 'rdar29691909_callee'}}
+}

test/Constraints/imported-overload.swift

@@ -0,0 +1,11 @@
+// RUN: %target-typecheck-verify-swift -import-objc-header %S/Inputs/overload.h
+// REQUIRES: objc_interop
+protocol rdar29374163Proto {}
+
+class rdar29374163 {
+  init(_ itf: Rdar29374163Itf) { self.itf = itf }
+  var itf: Rdar29374163Itf
+  func bar() -> Int {
+    return itf.foo as! Int
+  }
+}