Merge pull request swiftlang#30440 from LucianoPAlmeida/SR-11540-ambiguos-closure-inference

[SR-11540] Fix ambiguos overload apply to argument for contextual closure

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -1685,6 +1685,7 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
         if (isSingleTupleParam(ctx, func2Params) &&
             canImplodeParams(func1Params)) {
           implodeParams(func1Params);
+          increaseScore(SK_FunctionConversion);
         } else if (!ctx.isSwiftVersionAtLeast(5) &&
                    isSingleTupleParam(ctx, func1Params) &&
                    canImplodeParams(func2Params)) {
@@ -1697,6 +1698,7 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
                isa<OverloadedDeclRefExpr>(simplified) ||
                isa<UnresolvedDeclRefExpr>(simplified))) {
             implodeParams(func2Params);
+            increaseScore(SK_FunctionConversion);
           }
         }
       } else if (last->getKind() == ConstraintLocator::PatternMatch &&
@@ -1724,9 +1726,11 @@ ConstraintSystem::matchFunctionTypes(FunctionType *func1, FunctionType *func2,
         if (isSingleTupleParam(ctx, func1Params) &&
             canImplodeParams(func2Params)) {
           implodeParams(func2Params);
+          increaseScore(SK_FunctionConversion);
         } else if (isSingleTupleParam(ctx, func2Params) &&
                    canImplodeParams(func1Params)) {
           implodeParams(func1Params);
+          increaseScore(SK_FunctionConversion);
         }
       }
     }

test/Constraints/diag_ambiguities.swift

@@ -18,16 +18,16 @@ func +++(d: Double, i: Int) {} // expected-note{{found this candidate}}
 1 +++ 2 // expected-error{{ambiguous use of operator '+++'}}
 
 class C {
-  init(_ action: (Int) -> ()) {} // expected-note{{found this candidate}}
-  init(_ action: (Int, Int) -> ()) {} // expected-note{{found this candidate}}
+  init(_ action: (Int) -> ()) {} 
+  init(_ action: (Int, Int) -> ()) {} 
 }
 
 func g(_ x: Int) -> () {} // expected-note{{found this candidate}}
 func g(_ x: Int, _ y: Int) -> () {} // expected-note{{found this candidate}}
 C(g) // expected-error{{ambiguous use of 'g'}}
 
 func h<T>(_ x: T) -> () {}
-C(h) // expected-error{{ambiguous use of 'init(_:)'}}
+_ = C(h) // OK - init(_: (Int) -> ())
 
 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}}

test/expr/closure/inference.swift

@@ -38,3 +38,16 @@ var nestedClosuresWithBrokenInference = { f: Int in {} }
     // expected-error@-2 {{consecutive statements on a line must be separated by ';'}} {{44-44=;}}
     // expected-error@-3 {{expected expression}}
     // expected-error@-4 {{use of unresolved identifier 'f'}}
+
+// SR-11540
+
+func SR11540<R>(action: () -> R) -> Void {}
+
+func SR11540<T, R>(action: (T) -> R) -> Void {}
+
+func SR11540_1<T, R>(action: (T) -> R) -> Void {} 
+
+SR11540(action: { return }) // Ok SR11540<R>(action: () -> R) was the selected overload.
+
+// In case that's the only possible overload, it's acceptable
+SR11540_1(action: { return }) // OK