Merge pull request #64490 from xedin/rdar-102412006

[CSFix] Diagnose an invalid member reference in ambiguous contexts

Author: xedin

include/swift/Sema/CSFix.h

@@ -1477,6 +1477,8 @@ class AllowInvalidMemberRef : public ConstraintFix {
   ValueDecl *getMember() const { return Member; }
 
   DeclNameRef getMemberName() const { return Name; }
+
+  bool diagnoseForAmbiguity(CommonFixesArray commonFixes) const override;
 };
 
 class AllowMemberRefOnExistential final : public AllowInvalidMemberRef {

lib/Sema/CSFix.cpp

@@ -947,6 +947,21 @@ bool AllowMemberRefOnExistential::diagnose(const Solution &solution,
   return failure.diagnose(asNote);
 }
 
+bool AllowInvalidMemberRef::diagnoseForAmbiguity(
+    CommonFixesArray commonFixes) const {
+  auto *primaryFix =
+      static_cast<const AllowInvalidMemberRef *>(commonFixes.front().second);
+
+  Type baseTy = primaryFix->getBaseType();
+  for (const auto &entry : commonFixes) {
+    auto *memberFix = static_cast<const AllowInvalidMemberRef *>(entry.second);
+    if (!baseTy->isEqual(memberFix->getBaseType()))
+      return false;
+  }
+
+  return diagnose(*commonFixes.front().first);
+}
+
 bool AllowTypeOrInstanceMember::diagnose(const Solution &solution,
                                          bool asNote) const {
   AllowTypeOrInstanceMemberFailure failure(solution, getBaseType(), getMember(),

test/Constraints/dynamic_lookup.swift

@@ -471,3 +471,18 @@ func testAnyObjectConstruction(_ x: AnyObject) {
   // FIXME: This should also be rejected.
   _ = type(of: x).init()
 }
+
+// rdar://102412006 - failed to produce a diagnostic for invalid member ref
+class AmbiguityA : NSObject {
+  @objc class var testProp: A { get { A() } }
+}
+
+
+class AmbuguityB : NSObject {
+  @objc class var testProp: B { get { B() } }
+}
+
+do {
+  func test(_: AnyObject?) {}
+  test(.testProp) // expected-error {{static member 'testProp' cannot be used on protocol metatype '(any AnyObject).Type'}}
+}