[Sema] Allow @objc on enum cases

Author: lilyball

include/swift/AST/Attr.def

@@ -92,7 +92,7 @@ SIMPLE_DECL_ATTR(final, Final,
 
 DECL_ATTR(objc, ObjC,
           OnFunc | OnClass | OnProtocol | OnVar | OnSubscript |
-          OnConstructor | OnDestructor | OnEnum, 3)
+          OnConstructor | OnDestructor | OnEnum | OnEnumElement, 3)
 
 SIMPLE_DECL_ATTR(required, Required,
                  OnConstructor|DeclModifier, 4)

include/swift/AST/DiagnosticsSema.def

@@ -2333,7 +2333,7 @@ ERROR(objc_setter_for_nonobjc_subscript,sema_tcd,none,
 ERROR(objc_enum_generic,sema_tcd,none,
       "'@objc' enum cannot be generic", ())
 ERROR(objc_name_req_nullary,sema_objc,none,
-      "'@objc' %select{class|protocol|enum|property}0 must have a simple name", (int))
+      "'@objc' %select{class|protocol|enum|enum case|property}0 must have a simple name", (int))
 ERROR(objc_name_subscript,sema_objc,none,
       "'@objc' subscript cannot have a name; did you mean to put "
       "the name on the getter or setter?", ())
@@ -2343,6 +2343,13 @@ ERROR(objc_name_func_mismatch,sema_objc,none,
       "%select{initializer|method}0 has %select{one parameter|%3 parameters}4"
       "%select{| (%select{|including }4the error parameter)}5",
       (bool, unsigned, bool, unsigned, bool, bool))
+ERROR(objc_enum_case_req_name,sema_objc,none,
+      "attribute has no effect; cases within an '@objc' enum are already "
+      "exposed to Objective-C", ())
+ERROR(objc_enum_case_req_objc_enum,sema_objc,none,
+      "'@objc' enum case is not allowed outside of an '@objc' enum", ())
+ERROR(objc_enum_case_multi,sema_objc,none,
+      "'@objc' enum case declaration defines multiple enum cases with the same Objective-C name", ())
 
 // If you change this, also change enum ObjCReason
 #define OBJC_ATTR_SELECT "select{marked dynamic|marked @objc|marked @IBOutlet|marked @NSManaged|a member of an @objc protocol|implicitly @objc|an @objc override}"

lib/Sema/TypeCheckDecl.cpp

@@ -7004,6 +7004,12 @@ static void validateAttributes(TypeChecker &TC, Decl *D) {
     } else if (auto ED = dyn_cast<EnumDecl>(D)) {
       if (ED->isGenericContext())
         error = diag::objc_enum_generic;
+    } else if (auto EED = dyn_cast<EnumElementDecl>(D)) {
+      auto ED = EED->getParentEnum();
+      if (!ED->getAttrs().hasAttribute<ObjCAttr>())
+        error = diag::objc_enum_case_req_objc_enum;
+      else if (objcAttr->hasName() && EED->getParentCase()->getElements().size() > 1)
+        error = diag::objc_enum_case_multi;
     } else if (isa<FuncDecl>(D)) {
       auto func = cast<FuncDecl>(D);
       if (!checkObjCDeclContext(D))
@@ -7033,16 +7039,17 @@ static void validateAttributes(TypeChecker &TC, Decl *D) {
     // If there is a name, check whether the kind of name is
     // appropriate.
     if (auto objcName = objcAttr->getName()) {
-      if (isa<ClassDecl>(D) || isa<ProtocolDecl>(D) || isa<EnumDecl>(D) ||
-          isa<VarDecl>(D)) {
+      if (isa<ClassDecl>(D) || isa<ProtocolDecl>(D) || isa<VarDecl>(D)
+          || isa<EnumDecl>(D) || isa<EnumElementDecl>(D)) {
         // Types and properties can only have nullary
         // names. Complain and recover by chopping off everything
         // after the first name.
         if (objcName->getNumArgs() > 0) {
           int which = isa<ClassDecl>(D)? 0
                     : isa<ProtocolDecl>(D)? 1
                     : isa<EnumDecl>(D)? 2
-                    : 3;
+                    : isa<EnumElementDecl>(D)? 3
+                    : 4;
           SourceLoc firstNameLoc = objcAttr->getNameLocs().front();
           SourceLoc afterFirstNameLoc = 
             Lexer::getLocForEndOfToken(TC.Context.SourceMgr, firstNameLoc);
@@ -7091,6 +7098,11 @@ static void validateAttributes(TypeChecker &TC, Decl *D) {
           D->getAttrs().removeAttribute(objcAttr);
         }
       }
+    } else if (isa<EnumElementDecl>(D)) {
+      // Enum elements require names.
+      TC.diagnose(objcAttr->getLocation(), diag::objc_enum_case_req_name)
+        .fixItRemove(objcAttr->getRangeWithAt());
+      objcAttr->setInvalid();
     }
   }
 

test/attr/attr_objc.swift

@@ -194,16 +194,33 @@ extension subject_genericClass {
 
 @objc
 enum subject_enum: Int {
-  @objc   // expected-error {{@objc cannot be applied to this declaration}} {{3-9=}}
+  @objc   // expected-error {{attribute has no effect; cases within an '@objc' enum are already exposed to Objective-C}} {{3-9=}}
   case subject_enumElement1
 
+  @objc(subject_enumElement2)
+  case subject_enumElement2
+
+  @objc(subject_enumElement3)
+  case subject_enumElement3, subject_enumElement4 // expected-error {{'@objc' enum case declaration defines multiple enum cases with the same Objective-C name}}{{3-8=}}
+
+  @objc   // expected-error {{attribute has no effect; cases within an '@objc' enum are already exposed to Objective-C}} {{3-9=}}
+  case subject_enumElement5, subject_enumElement6
+
+  @nonobjc // expected-error {{@nonobjc cannot be applied to this declaration}}
+  case subject_enumElement7
+
   @objc   
   init() {} // expected-error {{@objc can only be used with members of classes, @objc protocols, and concrete extensions of classes}} {{3-9=}}
 
   @objc
   func subject_instanceFunc() {} // expected-error {{@objc can only be used with members of classes, @objc protocols, and concrete extensions of classes}} {{3-8=}}
 }
 
+enum subject_enum2 {
+  @objc(subject_enum2Element1)
+  case subject_enumElement1 // expected-error{{'@objc' enum case is not allowed outside of an '@objc' enum}}{{3-8=}}
+}
+
 @objc
 protocol subject_protocol1 {
   @objc
@@ -1752,6 +1769,12 @@ protocol BadProto1 { }
 @objc(Enum:) // expected-error{{'@objc' enum must have a simple name}}{{11-12=}}
 enum BadEnum1: Int { case X }
 
+@objc
+enum BadEnum2: Int {
+  @objc(X:)   // expected-error{{'@objc' enum case must have a simple name}}{{10-11=}}
+  case X
+}
+
 class BadClass2 {
   @objc(badprop:foo:wibble:) // expected-error{{'@objc' property must have a simple name}}{{16-28=}}
   var badprop: Int = 5