Merge pull request #30171 from CodaFi/object-permanence

[Sema] Don't Emit @objc Fixits Into Extant Modules

Author: CodaFi

lib/Sema/TypeCheckDeclOverride.cpp

@@ -1772,7 +1772,11 @@ static bool checkSingleOverride(ValueDecl *override, ValueDecl *base) {
     bool baseCanBeObjC = canBeRepresentedInObjC(base);
     diags.diagnose(override, diag::override_decl_extension, baseCanBeObjC,
                    !isa<ExtensionDecl>(base->getDeclContext()));
-    if (baseCanBeObjC) {
+    // If the base and the override come from the same module, try to fix
+    // the base declaration. Otherwise we can wind up diagnosing into e.g. the
+    // SDK overlay modules.
+    if (baseCanBeObjC &&
+        base->getModuleContext() == override->getModuleContext()) {
       SourceLoc insertionLoc =
         override->getAttributeInsertionLoc(/*forModifier=*/false);
       diags.diagnose(base, diag::overridden_here_can_be_objc)

test/ClangImporter/Inputs/custom-modules/ImageInitializers.h

@@ -0,0 +1,7 @@
+@import Foundation;
+
+@interface Image: NSObject
+
++ (instancetype)imageNamed:(NSString *)string;
+
+@end

test/ClangImporter/Inputs/custom-modules/module.map

@@ -59,6 +59,11 @@ module HasSubmodule {
   }
 }
 
+module ImageInitializers {
+  header "ImageInitializers.h"
+  export *
+}
+
 module ImportsMissingHeader {
   header "ImportsMissingHeader.h"
   export *

test/ClangImporter/Inputs/overlay_extension_initializer.swift

@@ -0,0 +1,12 @@
+@_exported import ImageInitializers
+
+extension Image : _ExpressibleByImageLiteral {
+  private convenience init!(failableImageLiteral name: String) {
+    self.init(named: .init(name))
+  }
+
+  @nonobjc
+  public required convenience init(imageLiteralResourceName name: String) {
+    self.init(failableImageLiteral: name)
+  }
+}

test/ClangImporter/objc-cross-module-override.swift

@@ -0,0 +1,19 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-module %S/Inputs/overlay_extension_initializer.swift -Xcc -isystem -Xcc %S/Inputs/custom-modules -module-name ImageInitializers -o %t
+// RUN: not %target-swift-frontend -I %S/Inputs/custom-modules -I %t -typecheck -primary-file %s 2>&1 | %FileCheck %s
+
+// REQUIRES: objc_interop
+
+// N.B. This test is a bit odd since we are going to check for the presence of a
+// diagnostic being emitted in a different module. The diagnostic verifier isn't
+// really setup to test that yet.
+
+import ImageInitializers
+
+final class MyImage : Image {
+  // CHECK: overriding non-@objc declarations from extensions is not supported
+  // Make sure we aren't emitting a fixit into the extant module...
+  // CHECK-NOT: add '@objc' to make this declaration overridable
+  // CHECK: ImageInitializers.Image:{{.*}}: note: overridden declaration is here
+  override required convenience init(imageLiteralResourceName name: String) { }
+}