Merge pull request #31412 from xedin/rdar-61911108

[ConstraintSystem] Don't attempt property wrapper fixes for key path …

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -2602,6 +2602,11 @@ static ConstraintFix *fixPropertyWrapperFailure(
     ConstraintSystem &cs, Type baseTy, ConstraintLocator *locator,
     llvm::function_ref<bool(SelectedOverload, VarDecl *, Type)> attemptFix,
     Optional<Type> toType = None) {
+  // Don't attempt this fix if this is a key path dynamic member
+  // lookup which produced no results. Unwrapping or wrapping
+  // the base type is not going to produce desired results.
+  if (locator->isForKeyPathDynamicMemberLookup())
+    return nullptr;
 
   Expr *baseExpr = nullptr;
   if (auto *anchor = getAsExpr(locator->getAnchor())) {

test/Constraints/sr12520.swift

@@ -0,0 +1,38 @@
+// RUN: %target-typecheck-verify-swift
+
+@propertyWrapper
+@dynamicMemberLookup
+struct Binding<Value> {
+  var wrappedValue: Value
+
+  subscript<Subject>(dynamicMember keyPath: WritableKeyPath<Value, Subject>) -> Binding<Subject> {
+    get { fatalError() }
+  }
+}
+
+@propertyWrapper
+struct Wrapper<Value> {
+  var wrappedValue: Value
+  var projectedValue: Binding<Value>
+}
+
+@dynamicMemberLookup class Foo {
+  struct State {
+    let value: Bool
+  }
+
+  let currentState: State = State(value: false)
+
+  subscript<U>(dynamicMember keyPath: KeyPath<State, U>) -> U {
+    return currentState[keyPath: keyPath]
+  }
+}
+
+struct Test {
+  @Wrapper var foo: Foo
+
+  func test() {
+    if foo.bar { // expected-error {{value of type 'Foo' has no dynamic member 'bar' using key path from root type 'Foo.State'}}
+    }
+  }
+}