Adding condition on repair to handle explicit coercion

Author: LucianoPAlmeida

lib/Sema/CSDiagnostics.cpp

@@ -956,8 +956,15 @@ bool NoEscapeFuncToTypeConversionFailure::diagnoseParameterUse() const {
 }
 
 bool MissingForcedDowncastFailure::diagnoseAsError() {
-  if (hasComplexLocator())
-    return false;
+  bool isExplicitCoercion =
+      getLocator()
+          ->isLastElement<
+              ConstraintLocator::PathElement::ExplicitTypeCoercion>();
+
+  if (!isExplicitCoercion) {
+    if (hasComplexLocator())
+      return false;
+  }
 
   auto *expr = getAnchor();
   if (auto *assignExpr = dyn_cast<AssignExpr>(expr))

lib/Sema/CSSimplify.cpp

@@ -2503,7 +2503,8 @@ bool ConstraintSystem::repairFailures(
                         });
   };
 
-  if (path.empty()) {
+  if (path.empty() ||
+      path.back().getKind() == ConstraintLocator::ExplicitTypeCoercion) {
     if (!anchor)
       return false;
 
@@ -3125,7 +3126,8 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
   if (!(desugar1->is<DependentMemberType>() &&
         desugar2->is<DependentMemberType>())) {
     if (desugar1->isEqual(desugar2)) {
-      if (kind >= ConstraintKind::Conversion) {
+      if (kind >= ConstraintKind::Conversion &&
+          !flags.contains(TMF_ApplyingFix)) {
         if (RemoveUnnecessaryCoercion::attempt(*this, type1, type2,
                                                getConstraintLocator(locator))) {
           return getTypeMatchFailure(locator);

test/Sema/suppress-argument-labels-in-types.swift

@@ -207,18 +207,18 @@ let _ = min(Int(3), Float(2.5)) // expected-error{{cannot convert value of type
 
 // SR-11429
 func testIntermediateCoercions() {
-  _ = (f1 as (Int, Int) -> Int)(a: 0, b: 1) // expected-error {{extraneous argument labels 'a:b:' in call}}
-  _ = (f1 as (Int, Int) -> Int)(0, 1)
+  _ = (f1 as (Int, Int) -> Int)(a: 0, b: 1) // expected-error {{extraneous argument labels 'a:b:' in call}} expected-warning {{redundant cast to '(Int, Int) -> Int' has no effect}}
+  _ = (f1 as (Int, Int) -> Int)(0, 1) // expected-warning {{redundant cast to '(Int, Int) -> Int' has no effect}}
 
   typealias Magic<T> = T
-  _ = (f1 as Magic)(a: 0, b: 1) // expected-error {{extraneous argument labels 'a:b:' in call}}
-  _ = (f1 as Magic)(0, 1)
+  _ = (f1 as Magic)(a: 0, b: 1) // expected-error {{extraneous argument labels 'a:b:' in call}} expected-warning {{redundant cast to '(Int, Int) -> Int' has no effect}}
+  _ = (f1 as Magic)(0, 1) // expected-warning {{redundant cast to '(Int, Int) -> Int' has no effect}}
 
   _ = (f4 as (Int, Int) -> Int)(0, 0)
   _ = (f4 as (Double, Double) -> Double)(0, 0)
 
   func iuoReturning() -> Int! {}
-  _ = (iuoReturning as () -> Int?)()
-  _ = (iuoReturning as Magic)()
+  _ = (iuoReturning as () -> Int?)() // expected-warning {{redundant cast to '() -> Int?' has no effect}}
+  _ = (iuoReturning as Magic)() // expected-warning {{redundant cast to '() -> Int?' has no effect}}
   _ = (iuoReturning as () -> Int)() // expected-error {{cannot convert value of type '() -> Int?' to type '() -> Int' in coercion}}
 }