Add ObjCReason for @objcImpl

Besides improving diagnostics, this also allows us to track whether there were any @objc failures using the invalid bit on the @_objcImplementation attribute.

Author: beccadax

include/swift/AST/DiagnosticsSema.def

@@ -6100,7 +6100,7 @@ ERROR(objc_extension_not_class,none,
       "'@objc' can only be applied to an extension of a class", ())
 
 // If you change this, also change enum ObjCReason
-#define OBJC_ATTR_SELECT "select{marked @_cdecl|marked dynamic|marked @objc|marked @objcMembers|marked @IBOutlet|marked @IBAction|marked @IBSegueAction|marked @NSManaged|a member of an @objc protocol|implicitly @objc|an @objc override|an implementation of an @objc requirement|marked @IBInspectable|marked @GKInspectable|in an @objc extension of a class (without @nonobjc)|marked @objc by an access note}"
+#define OBJC_ATTR_SELECT "select{marked @_cdecl|marked dynamic|marked @objc|marked @objcMembers|marked @IBOutlet|marked @IBAction|marked @IBSegueAction|marked @NSManaged|a member of an @objc protocol|implicitly @objc|an @objc override|an implementation of an @objc requirement|marked @IBInspectable|marked @GKInspectable|in an @objc extension of a class (without @nonobjc)|in an @_objcImplementation extension of a class (without final or @nonobjc)|marked @objc by an access note}"
 
 WARNING(attribute_meaningless_when_nonobjc,none,
         "'@%0' attribute is meaningless on a property that cannot be "

lib/AST/Decl.cpp

@@ -1818,7 +1818,7 @@ Type ExtensionDecl::getExtendedType() const {
 }
 
 bool ExtensionDecl::isObjCImplementation() const {
-  return getAttrs().hasAttribute<ObjCImplementationAttr>();
+  return getAttrs().hasAttribute<ObjCImplementationAttr>(/*AllowInvalid=*/true);
 }
 
 llvm::Optional<Identifier>

lib/Sema/TypeCheckDeclObjC.cpp

@@ -51,6 +51,7 @@ swift::behaviorLimitForObjCReason(ObjCReason reason, ASTContext &ctx) {
   case ObjCReason::WitnessToObjC:
   case ObjCReason::ImplicitlyObjC:
   case ObjCReason::MemberOfObjCExtension:
+  case ObjCReason::MemberOfObjCImplementationExtension:
     return DiagnosticBehavior::Unspecified;
 
   case ObjCReason::ExplicitlyIBInspectable:
@@ -88,6 +89,7 @@ unsigned swift::getObjCDiagnosticAttrKind(ObjCReason reason) {
   case ObjCReason::ExplicitlyIBInspectable:
   case ObjCReason::ExplicitlyGKInspectable:
   case ObjCReason::MemberOfObjCExtension:
+  case ObjCReason::MemberOfObjCImplementationExtension:
   case ObjCReason::ExplicitlyObjCByAccessNote:
     return static_cast<unsigned>(reason);
 
@@ -137,6 +139,7 @@ void ObjCReason::describe(const Decl *D) const {
   case ObjCReason::MemberOfObjCExtension:
   case ObjCReason::MemberOfObjCMembersClass:
   case ObjCReason::MemberOfObjCSubclass:
+  case ObjCReason::MemberOfObjCImplementationExtension:
   case ObjCReason::ElementOfObjCEnum:
   case ObjCReason::Accessor:
     // No additional note required.
@@ -1463,9 +1466,12 @@ static llvm::Optional<ObjCReason> shouldMarkAsObjC(const ValueDecl *VD,
   }
 
   // A member implementation of an @objcImplementation extension is @objc.
-  if (VD->isObjCMemberImplementation())
-    // FIXME: New ObjCReason::Kind?
-    return ObjCReason(ObjCReason::ImplicitlyObjC);
+  if (VD->isObjCMemberImplementation()) {
+    auto ext = VD->getDeclContext()->getAsDecl();
+    auto attr = ext->getAttrs()
+                  .getAttribute<ObjCImplementationAttr>(/*AllowInvalid=*/true);
+    return ObjCReason(ObjCReason::MemberOfObjCImplementationExtension, attr);
+  }
 
   // A @nonobjc is not @objc, even if it is an override of an @objc, so check
   // for @nonobjc first.

lib/Sema/TypeCheckObjC.h

@@ -71,6 +71,8 @@ class ObjCReason {
     ExplicitlyGKInspectable,
     /// Is it a member of an @objc extension of a class.
     MemberOfObjCExtension,
+    /// Is it a member of an \@\_objcImplementation extension.
+    MemberOfObjCImplementationExtension,
     /// Has an explicit '@objc' attribute added by an access note, rather than
     /// written in source code.
     ExplicitlyObjCByAccessNote,
@@ -108,6 +110,7 @@ class ObjCReason {
     case ExplicitlyNSManaged:
     case ExplicitlyIBInspectable:
     case ExplicitlyGKInspectable:
+    case MemberOfObjCImplementationExtension:
     case ExplicitlyObjCByAccessNote:
       return true;
 

test/decl/ext/objc_implementation.swift

@@ -412,8 +412,8 @@ protocol EmptySwiftProto {}
   func nullableResult() -> Any { fatalError() } // expected-warning {{instance method 'nullableResult()' of type '() -> Any' does not match type '() -> Any?' declared by the header}}
   func nullableArgument(_: Any) {} // expected-warning {{instance method 'nullableArgument' of type '(Any) -> ()' does not match type '(Any?) -> Void' declared by the header}}
 
-  func nonPointerResult() -> CInt! { fatalError() } // expected-error{{method cannot be implicitly @objc because its result type cannot be represented in Objective-C}}
-  func nonPointerArgument(_: CInt!) {} // expected-error {{method cannot be implicitly @objc because the type of the parameter cannot be represented in Objective-C}}
+  func nonPointerResult() -> CInt! { fatalError() } // expected-error{{method cannot be in an @_objcImplementation extension of a class (without final or @nonobjc) because its result type cannot be represented in Objective-C}}
+  func nonPointerArgument(_: CInt!) {} // expected-error {{method cannot be in an @_objcImplementation extension of a class (without final or @nonobjc) because the type of the parameter cannot be represented in Objective-C}}
 }
 
 @_objcImplementation extension ObjCImplSubclass {