[CSFix] Add a fix to add a missing qualifier to shadowed top-level name references

Author: xedin

lib/Sema/CSFix.cpp

@@ -1217,3 +1217,13 @@ AllowNonClassTypeToConvertToAnyObject::create(ConstraintSystem &cs, Type type,
   return new (cs.getAllocator())
       AllowNonClassTypeToConvertToAnyObject(cs, type, locator);
 }
+
+bool AddQualifierToAccessTopLevelName::diagnose(bool asNote) const {
+  return false;
+}
+
+AddQualifierToAccessTopLevelName *
+AddQualifierToAccessTopLevelName::create(ConstraintSystem &cs,
+                                         ConstraintLocator *locator) {
+  return new (cs.getAllocator()) AddQualifierToAccessTopLevelName(cs, locator);
+}

lib/Sema/CSFix.h

@@ -244,6 +244,10 @@ enum class FixKind : uint8_t {
   /// Allow any type (and not just class or class-constrained type) to
   /// be convertible to AnyObject.
   AllowNonClassTypeToConvertToAnyObject,
+
+  /// Member shadows a top-level name, such a name could only be accessed by
+  /// prefixing it with a module name.
+  AddQualifierToAccessTopLevelName,
 };
 
 class ConstraintFix {
@@ -1655,7 +1659,22 @@ class SpecifyObjectLiteralTypeImport final : public ConstraintFix {
 
   static SpecifyObjectLiteralTypeImport *create(ConstraintSystem &cs,
                                                 ConstraintLocator *locator);
+};
+
+class AddQualifierToAccessTopLevelName final : public ConstraintFix {
+  AddQualifierToAccessTopLevelName(ConstraintSystem &cs,
+                                   ConstraintLocator *locator)
+      : ConstraintFix(cs, FixKind::AddQualifierToAccessTopLevelName, locator) {}
+
+public:
+  std::string getName() const {
+    return "qualify reference to access top-level function";
+  }
 
+  bool diagnose(bool asNote = false) const;
+
+  static AddQualifierToAccessTopLevelName *create(ConstraintSystem &cs,
+                                                  ConstraintLocator *locator);
 };
 
 class AllowNonClassTypeToConvertToAnyObject final : public ContextualMismatch {