Merge pull request #11089 from jckarter/quoted-subscript-identifier-4.0

[4.0] Don't consider KeyPathApplication operations when looking up non-SubscriptExprs.

Author: jckarter

lib/Sema/CSDiag.cpp

@@ -2845,6 +2845,11 @@ bool FailureDiagnosis::diagnoseGeneralConversionFailure(Constraint *constraint){
     fromType = sub->getType();
   }
 
+  // Bail on constraints that don't relate two types.
+  if (constraint->getKind() == ConstraintKind::Disjunction
+      || constraint->getKind() == ConstraintKind::BindOverload)
+    return false;
+
   fromType = fromType->getRValueType();
   auto toType = CS->simplifyType(constraint->getSecondType())
                   ->getWithoutImmediateLabel();

lib/Sema/CSSimplify.cpp

@@ -2891,7 +2891,9 @@ performMemberLookup(ConstraintKind constraintKind, DeclName memberName,
   result.OverallResult = MemberLookupResult::HasResults;
 
   // If we're looking for a subscript, consider key path operations.
-  if (memberName.isSimpleName(getASTContext().Id_subscript)) {
+  if (memberName.isSimpleName(getASTContext().Id_subscript)
+      && (isa<SubscriptExpr>(memberLocator->getAnchor())
+          || isa<KeyPathExpr>(memberLocator->getAnchor()))) {
     result.ViableCandidates.push_back(
         OverloadChoice(baseTy, OverloadChoiceKind::KeyPathApplication));
   }

lib/Sema/ConstraintGraph.cpp

@@ -641,7 +641,6 @@ static bool shouldContractEdge(ConstraintKind kind) {
   case ConstraintKind::BindParam:
   case ConstraintKind::BindToPointerType:
   case ConstraintKind::Equal:
-  case ConstraintKind::BindOverload:
 
   // We currently only allow subtype contractions for the purpose of 
   // parameter binding constraints.

test/decl/subscript/quoted-subscript-identifier.swift

@@ -0,0 +1,10 @@
+// RUN: %target-swift-frontend -typecheck -verify %s
+// SR-5513
+
+class OTTextView {
+  func `subscript`(_ sender: Any?) {}
+}
+
+class MyTextView: OTTextView {
+  override func `subscript`(_ sender: Any?) { super.`subscript`(sender) }
+}