SE-495: Make @c an official feature

include/swift/AST/DiagnosticsSema.def

@@ -2114,9 +2114,6 @@ ERROR(cdecl_throws,none,
 ERROR(cdecl_incompatible_with_objc,none,
       "cannot apply both '@c' and '@objc' to %kindonly0",
       (const Decl *))
-ERROR(cdecl_feature_required,none,
-      "'@c' requires '-enable-experimental-feature CDecl'",
-      ())
 
 // @used and @section
 ERROR(section_empty_name,none,
@@ -6704,8 +6701,6 @@ NOTE(not_objc_swift_class,none,
 NOTE(not_objc_swift_struct,none,
       "Swift structs cannot be represented in %" FOREIGN_LANG_SELECT "0",
      (ForeignLanguage))
-NOTE(not_objc_swift_enum,none,
-      "non-'@objc' enums cannot be represented in Objective-C", ())
 NOTE(not_cdecl_or_objc_swift_enum,none,
      "Swift enums not marked '@c'%select{| or '@objc'}0 cannot be "
      "represented in %" FOREIGN_LANG_SELECT "0",

include/swift/Basic/Features.def

@@ -469,9 +469,6 @@ EXPERIMENTAL_FEATURE(ClosureIsolation, true)
 // staging purposes.
 EXPERIMENTAL_FEATURE(ObjCImplementationWithResilientStorage, true)
 
-// Enable @implementation on @_cdecl functions.
-EXPERIMENTAL_FEATURE(CImplementation, true)
-
 // Enable @sensitive attribute.
 EXPERIMENTAL_FEATURE(Sensitive, true)
 
@@ -529,9 +526,6 @@ EXPERIMENTAL_FEATURE(ClosureBodyMacro, true)
 /// Allow declarations of Swift runtime symbols using @_silgen_name.
 EXPERIMENTAL_FEATURE(AllowRuntimeSymbolDeclarations, true)
 
-/// Allow use of `@c`
-EXPERIMENTAL_FEATURE(CDecl, false)
-
 /// Allow use of `using` declaration that control default isolation
 /// in a file scope.
 EXPERIMENTAL_FEATURE(DefaultIsolationPerFile, false)

lib/AST/FeatureSet.cpp

@@ -277,7 +277,6 @@ UNINTERESTING_FEATURE(IsolatedAny2)
 UNINTERESTING_FEATURE(GlobalActorIsolatedTypesUsability)
 UNINTERESTING_FEATURE(ObjCImplementation)
 UNINTERESTING_FEATURE(ObjCImplementationWithResilientStorage)
-UNINTERESTING_FEATURE(CImplementation)
 UNINTERESTING_FEATURE(Sensitive)
 UNINTERESTING_FEATURE(DebugDescriptionMacro)
 UNINTERESTING_FEATURE(ReinitializeConsumeInMultiBlockDefer)
@@ -322,11 +321,6 @@ static bool usesFeatureClosureBodyMacro(Decl *decl) {
   return false;
 }
 
-static bool usesFeatureCDecl(Decl *decl) {
-  auto attr = decl->getAttrs().getAttribute<CDeclAttr>();
-  return attr && !attr->Underscored;
-}
-
 UNINTERESTING_FEATURE(StrictMemorySafety)
 UNINTERESTING_FEATURE(LibraryEvolution)
 UNINTERESTING_FEATURE(SafeInteropWrappers)

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -542,16 +542,10 @@ class ModuleWriter {
     assert(ED->isCCompatibleEnum() || ED->hasClangNode());
 
     forwardDeclare(ED, [&]{
-      if (ED->getASTContext().LangOpts.hasFeature(Feature::CDecl)) {
-        // Forward declare in a way to be compatible with older C standards.
-        os << "typedef SWIFT_ENUM_FWD_DECL(";
-        printer.print(ED->getRawType());
-        os << ", " << getNameForObjC(ED) << ")\n";
-      } else {
-        os << "enum " << getNameForObjC(ED) << " : ";
-        printer.print(ED->getRawType());
-        os << ";\n";
-      }
+      // Forward declare in a way to be compatible with older C standards.
+      os << "typedef SWIFT_ENUM_FWD_DECL(";
+      printer.print(ED->getRawType());
+      os << ", " << getNameForObjC(ED) << ")\n";
     });
   }
 

lib/PrintAsClang/PrintAsClang.cpp

@@ -220,20 +220,18 @@ static void writePrologue(raw_ostream &out, ASTContext &ctx,
   static_assert(SWIFT_MAX_IMPORTED_SIMD_ELEMENTS == 4,
               "need to add SIMD typedefs here if max elements is increased");
 
-  if (ctx.LangOpts.hasFeature(Feature::CDecl)) {
-    // For C compilers which don’t support nullability attributes, ignore them;
-    // for ones which do, suppress warnings about them being an extension.
-    out << "#if !__has_feature(nullability)\n"
-           "# define _Nonnull\n"
-           "# define _Nullable\n"
-           "# define _Null_unspecified\n"
-           "#elif !defined(__OBJC__)\n"
-           "# pragma clang diagnostic ignored \"-Wnullability-extension\"\n"
-           "#endif\n"
-           "#if !__has_feature(nullability_nullable_result)\n"
-           "# define _Nullable_result _Nullable\n"
-           "#endif\n";
-  }
+  // For C compilers which don’t support nullability attributes, ignore them;
+  // for ones which do, suppress warnings about them being an extension.
+  out << "#if !__has_feature(nullability)\n"
+         "# define _Nonnull\n"
+         "# define _Nullable\n"
+         "# define _Null_unspecified\n"
+         "#elif !defined(__OBJC__)\n"
+         "# pragma clang diagnostic ignored \"-Wnullability-extension\"\n"
+         "#endif\n"
+         "#if !__has_feature(nullability_nullable_result)\n"
+         "# define _Nullable_result _Nullable\n"
+         "#endif\n";
 }
 
 static int compareImportModulesByName(const ImportModuleTy *left,
@@ -618,7 +616,7 @@ bool swift::printAsClangHeader(raw_ostream &os, ModuleDecl *M,
 
   // C content (@c)
   std::string moduleContentsScratch;
-  if (M->getASTContext().LangOpts.hasFeature(Feature::CDecl)) {
+  {
     SmallPtrSet<ImportModuleTy, 8> imports;
     llvm::raw_string_ostream cModuleContents{moduleContentsScratch};
     printModuleContentsAsC(cModuleContents, imports, *M, interopContext,

lib/Sema/TypeCheckAttr.cpp

@@ -1841,9 +1841,6 @@ visitObjCImplementationAttr(ObjCImplementationAttr *attr) {
     }
   }
   else if (auto AFD = dyn_cast<AbstractFunctionDecl>(D)) {
-    if (!hasObjCImplementationFeature(D, attr, Feature::CImplementation))
-      return;
-
     if (!attr->CategoryName.empty()) {
       auto diagnostic =
           diagnose(attr->getLocation(),
@@ -2486,12 +2483,6 @@ void AttributeChecker::visitCDeclAttr(CDeclAttr *attr) {
   if (D->getAttrs().getAttribute<ObjCAttr>()) {
     diagnose(attr->getLocation(), diag::cdecl_incompatible_with_objc, D);
   }
-
-  // @c needs to be enabled via a feature flag.
-  if (!attr->Underscored &&
-      !Ctx.LangOpts.hasFeature(Feature::CDecl)) {
-    diagnose(attr->getLocation(), diag::cdecl_feature_required);
-  }
 }
 
 void AttributeChecker::visitExposeAttr(ExposeAttr *attr) {

lib/Sema/TypeCheckDeclObjC.cpp

@@ -222,17 +222,11 @@ static void diagnoseTypeNotRepresentableInObjC(const DeclContext *DC,
 
   // Special diagnostic for enums.
   if (T->is<EnumType>()) {
-    if (DC->getASTContext().LangOpts.hasFeature(Feature::CDecl)) {
-      // New dialog mentioning @c.
-      diags.diagnose(TypeRange.Start, diag::not_cdecl_or_objc_swift_enum,
-                     language)
-          .highlight(TypeRange)
-          .limitBehavior(behavior);
-    } else {
-      diags.diagnose(TypeRange.Start, diag::not_objc_swift_enum)
-          .highlight(TypeRange)
-          .limitBehavior(behavior);
-    }
+    // New dialog mentioning @c.
+    diags.diagnose(TypeRange.Start, diag::not_cdecl_or_objc_swift_enum,
+                   language)
+        .highlight(TypeRange)
+        .limitBehavior(behavior);
     return;
   }
 
@@ -4193,15 +4187,6 @@ class ObjCImplementationChecker {
         !decl->getASTContext().LangOpts.hasFeature(Feature::ObjCImplementation))
       return;
 
-    if (isa<AbstractFunctionDecl>(decl) &&
-        !decl->getASTContext().LangOpts.hasFeature(Feature::CImplementation))
-      return;
-
-    // Only encourage @_objcImplementation *extension* adopters to adopt
-    // @implementation; @_objcImplementation @_cdecl hasn't been stabilized yet.
-    if (!isa<ExtensionDecl>(decl))
-      return;
-
     auto diag = diagnose(getAttr()->getLocation(),
                          diag::objc_implementation_early_spelling_deprecated);
     diag.fixItReplace(getAttr()->getRangeWithAt(), "@implementation");

test/ASTGen/attrs.swift

@@ -4,7 +4,6 @@
 // RUN:   -enable-experimental-feature Extern \
 // RUN:   -enable-experimental-feature Lifetimes \
 // RUN:   -enable-experimental-feature RawLayout \
-// RUN:   -enable-experimental-feature CDecl \
 // RUN:   -enable-experimental-concurrency \
 // RUN:   -enable-experimental-move-only \
 // RUN:   -enable-experimental-feature ParserASTGen \
@@ -14,7 +13,6 @@
 // RUN:   -enable-experimental-feature Extern \
 // RUN:   -enable-experimental-feature Lifetimes \
 // RUN:   -enable-experimental-feature RawLayout \
-// RUN:   -enable-experimental-feature CDecl \
 // RUN:   -enable-experimental-concurrency \
 // RUN:   -enable-experimental-move-only \
 // RUN:   | %sanitize-address > %t/cpp-parser.ast
@@ -27,7 +25,6 @@
 // RUN:   -enable-experimental-feature Extern \
 // RUN:   -enable-experimental-feature Lifetimes \
 // RUN:   -enable-experimental-feature RawLayout \
-// RUN:   -enable-experimental-feature CDecl \
 // RUN:   -enable-experimental-concurrency \
 // RUN:   -enable-experimental-move-only
 
@@ -37,7 +34,6 @@
 // REQUIRES: swift_feature_Extern
 // REQUIRES: swift_feature_Lifetimes
 // REQUIRES: swift_feature_RawLayout
-// REQUIRES: swift_feature_CDecl
 
 // rdar://116686158
 // UNSUPPORTED: asan

test/IRGen/cdecl_implementation.swift

@@ -1,15 +1,10 @@
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) \
-// RUN:   -enable-experimental-feature CImplementation \
-// RUN:   -enable-experimental-feature CDecl \
 // RUN:   -disable-objc-interop \
 // RUN:   -F %clang-importer-sdk-path/frameworks %s \
 // RUN:   -import-objc-header %S/Inputs/objc_implementation.h -emit-ir \
 // RUN:   -target %target-future-triple > %t.ir
 // RUN: %FileCheck --input-file %t.ir %s
 
-// REQUIRES: swift_feature_CImplementation
-// REQUIRES: swift_feature_CDecl
-
 @implementation @c
 public func implFunc(_ param: Int32) {}
 

test/IRGen/objc_implementation.swift

@@ -1,11 +1,10 @@
 // Test doesn't pass on all platforms (rdar://101420862)
 // REQUIRES: OS=macosx
 
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-experimental-feature CImplementation -I %S/Inputs/abi -F %clang-importer-sdk-path/frameworks %s -import-objc-header %S/Inputs/objc_implementation.h -emit-ir -target %target-future-triple > %t.ir
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -I %S/Inputs/abi -F %clang-importer-sdk-path/frameworks %s -import-objc-header %S/Inputs/objc_implementation.h -emit-ir -target %target-future-triple > %t.ir
 // RUN: %FileCheck --input-file %t.ir %s
 // RUN: %FileCheck --input-file %t.ir --check-prefix NEGATIVE %s
 // REQUIRES: objc_interop
-// REQUIRES: swift_feature_CImplementation
 
 // CHECK-DAG: @"$sSo36ImplClassWithResilientStoredPropertyC19objc_implementationE9beforeInts5Int32VvpWvd" = hidden global i64 8, align 8
 // CHECK-DAG: @"$sSo36ImplClassWithResilientStoredPropertyC19objc_implementationE6mirrors6MirrorVSgvpWvd" = hidden global i64 0, align 8

test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-cxx.swift

@@ -181,6 +181,7 @@ public struct Strct {
     public let transform2: ns.anonStructInNS
 }
 
+// CHECK: #if __has_feature(objc_modules)
 // CHECK: #if __has_feature(objc_modules)
 // CHECK: #if __has_feature(objc_modules)
 // CHECK-NEXT: #if __has_warning("-Watimport-in-framework-header")

test/Interpreter/cdecl_enum_run.swift

@@ -1,7 +1,6 @@
-// RUN: %target-run-simple-swift(-enable-experimental-feature CDecl) > %t.out
+// RUN: %target-run-simple-swift > %t.out
 // RUN: %FileCheck --input-file %t.out %s
 
-// REQUIRES: swift_feature_CDecl
 // REQUIRES: executable_test
 
 @c

test/Interpreter/cdecl_implementation_run.swift

@@ -5,9 +5,7 @@
 // RUN: %target-build-swift-dylib(%t/%target-library-name(Lib)) %t/Lib.swift \
 // RUN:   -emit-module-path %t/Lib.swiftmodule \
 // RUN:   -emit-clang-header-path %t/cdecl.h \
-// RUN:   -import-objc-header %t/BridgingHeader.h \
-// RUN:   -enable-experimental-feature CDecl \
-// RUN:   -enable-experimental-feature CImplementation
+// RUN:   -import-objc-header %t/BridgingHeader.h
 // RUN: %target-codesign %t/%target-library-name(Lib)
 
 /// Build a C client against cdecl.h.
@@ -25,8 +23,6 @@
 // RUN: %target-run %t/a.out %t/%target-library-name(Lib) > %t/run.log
 // RUN: %FileCheck %t/Client.swift --check-prefix=PRINTS --input-file %t/run.log
 
-// REQUIRES: swift_feature_CDecl
-// REQUIRES: swift_feature_CImplementation
 // REQUIRES: executable_test
 
 //--- BridgingHeader.h

test/Interpreter/cdecl_official_run.swift

@@ -6,21 +6,19 @@
 // RUN:   %t/Lib.swift -emit-module -verify -o %t -emit-module-doc \
 // RUN:   -emit-clang-header-path %t/cdecl.h \
 // RUN:   -disable-implicit-string-processing-module-import \
-// RUN:   -disable-implicit-concurrency-module-import \
-// RUN:   -enable-experimental-feature CDecl
+// RUN:   -disable-implicit-concurrency-module-import
 
 /// Build and run a binary from Swift and C code.
 // RUN: %clang-no-modules -c %t/Client.c -o %t/Client.o -target %target-triple \
 // RUN:   %target-pic-opt -I %t -I %clang-include-dir -Werror -isysroot %sdk
 // RUN: %target-build-swift %t/Lib.swift %t/Client.o -O -o %t/a.out \
 // RUN:   -Xfrontend -disable-implicit-string-processing-module-import \
 // RUN:   -Xfrontend -disable-implicit-concurrency-module-import \
-// RUN:   -enable-experimental-feature CDecl -parse-as-library
+// RUN:    -parse-as-library
 // RUN: %target-codesign %t/a.out
 // RUN: %target-run %t/a.out > %t/run.log
 // RUN: %FileCheck %s --input-file %t/run.log
 
-// REQUIRES: swift_feature_CDecl
 // REQUIRES: executable_test
 
 //--- Lib.swift

test/Interpreter/objc_implementation.swift

@@ -1,7 +1,6 @@
-// RUN: %target-run-simple-swift(-import-objc-header %S/Inputs/objc_implementation.h -D TOP_LEVEL_CODE -swift-version 5 -enable-experimental-feature CImplementation -target %target-stable-abi-triple) %s | %FileCheck %s
+// RUN: %target-run-simple-swift(-import-objc-header %S/Inputs/objc_implementation.h -D TOP_LEVEL_CODE -swift-version 5 -target %target-stable-abi-triple) %s | %FileCheck %s
 // REQUIRES: executable_test
 // REQUIRES: objc_interop
-// REQUIRES: swift_feature_CImplementation
 
 import Foundation
 

test/Interpreter/objc_implementation_objc_client.m

@@ -6,7 +6,7 @@
 // RUN: %empty-directory(%t/objc_implementation.framework/Headers)
 // RUN: cp %S/Inputs/objc_implementation.modulemap %t/objc_implementation.framework/Modules/module.modulemap
 // RUN: cp %S/Inputs/objc_implementation.h %t/objc_implementation.framework/Headers
-// RUN: %target-build-swift-dylib(%t/objc_implementation.framework/objc_implementation) -emit-module-path %t/objc_implementation.framework/Modules/objc_implementation.swiftmodule/%module-target-triple.swiftmodule -module-name objc_implementation -F %t -import-underlying-module -Xlinker -install_name -Xlinker @executable_path/objc_implementation.framework/objc_implementation %S/objc_implementation.swift -enable-experimental-feature CImplementation -target %target-stable-abi-triple
+// RUN: %target-build-swift-dylib(%t/objc_implementation.framework/objc_implementation) -emit-module-path %t/objc_implementation.framework/Modules/objc_implementation.swiftmodule/%module-target-triple.swiftmodule -module-name objc_implementation -F %t -import-underlying-module -Xlinker -install_name -Xlinker @executable_path/objc_implementation.framework/objc_implementation %S/objc_implementation.swift -target %target-stable-abi-triple
 
 //
 // Execute this file
@@ -22,7 +22,6 @@
 // FIXME: This test fails in Swift CI simulators, but I have not been able to
 //        reproduce this locally.
 // REQUIRES: OS=macosx
-// REQUIRES: swift_feature_CImplementation
 
 #import <Foundation/Foundation.h>
 #import <objc_implementation/objc_implementation.h>

test/Interpreter/objc_implementation_resilience.swift

@@ -2,10 +2,9 @@
 // Will not execute correctly without ObjC runtime support.
 // REQUIRES: rdar109171643
 
-// RUN: %target-run-simple-swift(-import-objc-header %S/Inputs/objc_implementation.h -D RESILIENCE -swift-version 5 -enable-experimental-feature CImplementation -enable-experimental-feature ObjCImplementationWithResilientStorage -target %target-future-triple %S/objc_implementation.swift) | %FileCheck %S/objc_implementation.swift --check-prefixes CHECK,CHECK-RESILIENCE
+// RUN: %target-run-simple-swift(-import-objc-header %S/Inputs/objc_implementation.h -D RESILIENCE -swift-version 5 -enable-experimental-feature ObjCImplementationWithResilientStorage -target %target-future-triple %S/objc_implementation.swift) | %FileCheck %S/objc_implementation.swift --check-prefixes CHECK,CHECK-RESILIENCE
 // REQUIRES: executable_test
 // REQUIRES: objc_interop
-// REQUIRES: swift_feature_CImplementation
 // REQUIRES: swift_feature_ObjCImplementationWithResilientStorage
 
 @main struct Main {

test/Interpreter/objc_implementation_resilience_objc_client.m

@@ -12,7 +12,7 @@
 // RUN: %empty-directory(%t-frameworks/objc_implementation.framework/Headers)
 // RUN: cp %S/Inputs/objc_implementation.modulemap %t-frameworks/objc_implementation.framework/Modules/module.modulemap
 // RUN: cp %S/Inputs/objc_implementation.h %t-frameworks/objc_implementation.framework/Headers
-// RUN: %target-build-swift-dylib(%t-frameworks/objc_implementation.framework/objc_implementation) -emit-module-path %t-frameworks/objc_implementation.framework/Modules/objc_implementation.swiftmodule/%module-target-triple.swiftmodule -module-name objc_implementation -F %t-frameworks -import-underlying-module -Xlinker -install_name -Xlinker %t-frameworks/objc_implementation.framework/objc_implementation %S/objc_implementation.swift -D RESILIENCE -enable-experimental-feature CImplementation -enable-experimental-feature ObjCImplementationWithResilientStorage -target %target-future-triple
+// RUN: %target-build-swift-dylib(%t-frameworks/objc_implementation.framework/objc_implementation) -emit-module-path %t-frameworks/objc_implementation.framework/Modules/objc_implementation.swiftmodule/%module-target-triple.swiftmodule -module-name objc_implementation -F %t-frameworks -import-underlying-module -Xlinker -install_name -Xlinker %t-frameworks/objc_implementation.framework/objc_implementation %S/objc_implementation.swift -D RESILIENCE -enable-experimental-feature ObjCImplementationWithResilientStorage -target %target-future-triple
 //
 // Execute this file
 //
@@ -27,5 +27,4 @@
 // FIXME: This test fails in Swift CI simulators, but I have not been able to
 //        reproduce this locally.
 // REQUIRES: OS=macosx
-// REQUIRES: swift_feature_CImplementation
 // REQUIRES: swift_feature_ObjCImplementationWithResilientStorage

test/Interpreter/objc_implementation_resilience_swift_client.swift

@@ -16,7 +16,7 @@
 // RUN: %empty-directory(%t/frameworks/objc_implementation.framework/Headers)
 // RUN: cp %S/Inputs/objc_implementation.modulemap %t/frameworks/objc_implementation.framework/Modules/module.modulemap
 // RUN: cp %S/Inputs/objc_implementation.h %t/frameworks/objc_implementation.framework/Headers
-// RUN: %target-build-swift-dylib(%t/frameworks/objc_implementation.framework/objc_implementation) -D RESILIENCE -enable-experimental-feature CImplementation -enable-experimental-feature ObjCImplementationWithResilientStorage -target %target-future-triple -emit-module-path %t/frameworks/objc_implementation.framework/Modules/objc_implementation.swiftmodule/%module-target-triple.swiftmodule -module-name objc_implementation -F %t/frameworks -import-underlying-module -Xlinker -install_name -Xlinker %t/frameworks/objc_implementation.framework/objc_implementation %S/objc_implementation.swift
+// RUN: %target-build-swift-dylib(%t/frameworks/objc_implementation.framework/objc_implementation) -D RESILIENCE -enable-experimental-feature ObjCImplementationWithResilientStorage -target %target-future-triple -emit-module-path %t/frameworks/objc_implementation.framework/Modules/objc_implementation.swiftmodule/%module-target-triple.swiftmodule -module-name objc_implementation -F %t/frameworks -import-underlying-module -Xlinker -install_name -Xlinker %t/frameworks/objc_implementation.framework/objc_implementation %S/objc_implementation.swift
 
 //
 // Execute this file
@@ -37,7 +37,6 @@
 
 // REQUIRES: executable_test
 // REQUIRES: objc_interop
-// REQUIRES: swift_feature_CImplementation
 // REQUIRES: swift_feature_ObjCImplementationWithResilientStorage
 
 @main struct Main {