[CSFix] Allow invalid decl references be diagnostic in ambiguity cases

Author: xedin

include/swift/Sema/CSFix.h

@@ -2070,6 +2070,10 @@ class AllowRefToInvalidDecl final : public ConstraintFix {
 
   bool diagnose(const Solution &solution, bool asNote = false) const override;
 
+  bool diagnoseForAmbiguity(CommonFixesArray commonFixes) const override {
+    return diagnose(*commonFixes.front().first);
+  }
+
   static AllowRefToInvalidDecl *create(ConstraintSystem &cs,
                                        ConstraintLocator *locator);
 };