Revert "[6.2] Accept @cdecl global functions and enums, behind experimental feature flags"

include/swift/AST/ASTBridging.h

@@ -949,12 +949,11 @@ BridgedBackDeployedAttr BridgedBackDeployedAttr_createParsed(
     BridgedSourceRange cRange, BridgedPlatformKind cPlatform,
     BridgedVersionTuple cVersion);
 
-SWIFT_NAME("BridgedCDeclAttr.createParsed(_:atLoc:range:name:underscored:)")
+SWIFT_NAME("BridgedCDeclAttr.createParsed(_:atLoc:range:name:)")
 BridgedCDeclAttr BridgedCDeclAttr_createParsed(BridgedASTContext cContext,
                                                BridgedSourceLoc cAtLoc,
                                                BridgedSourceRange cRange,
-                                               BridgedStringRef cName,
-                                               bool underscored);
+                                               BridgedStringRef cName);
 
 SWIFT_NAME(
     "BridgedCustomAttr.createParsed(_:atLoc:type:initContext:argumentList:)")

include/swift/AST/Attr.h

@@ -691,29 +691,22 @@ class SectionAttr : public DeclAttribute {
 /// Defines the @_cdecl attribute.
 class CDeclAttr : public DeclAttribute {
 public:
-  CDeclAttr(StringRef Name, SourceLoc AtLoc, SourceRange Range, bool Implicit,
-            bool Underscored)
-      : DeclAttribute(DeclAttrKind::CDecl, AtLoc, Range, Implicit),
-        Name(Name), Underscored(Underscored) {
+  CDeclAttr(StringRef Name, SourceLoc AtLoc, SourceRange Range, bool Implicit)
+      : DeclAttribute(DeclAttrKind::CDecl, AtLoc, Range, Implicit), Name(Name) {
   }
 
-  CDeclAttr(StringRef Name, bool Implicit, bool Underscored)
-    : CDeclAttr(Name, SourceLoc(), SourceRange(), Implicit, Underscored) {}
+  CDeclAttr(StringRef Name, bool Implicit)
+    : CDeclAttr(Name, SourceLoc(), SourceRange(), Implicit) {}
 
   /// The symbol name.
   const StringRef Name;
 
-  /// Is this the version of the attribute that's underscored?
-  /// Used to preserve retro compatibility with early adopters.
-  const bool Underscored;
-
   static bool classof(const DeclAttribute *DA) {
     return DA->getKind() == DeclAttrKind::CDecl;
   }
 
   CDeclAttr *clone(ASTContext &ctx) const {
-    return new (ctx) CDeclAttr(Name, AtLoc, Range, isImplicit(),
-                               Underscored);
+    return new (ctx) CDeclAttr(Name, AtLoc, Range, isImplicit());
   }
 
   bool isEquivalent(const CDeclAttr *other, Decl *attachedTo) const {

include/swift/AST/Decl.h

@@ -8172,11 +8172,6 @@ class AbstractFunctionDecl : public GenericContext, public ValueDecl {
   /// instance method.
   bool isObjCInstanceMethod() const;
 
-  /// Get the foreign language targeted by a @cdecl-style attribute, if any.
-  /// Used to abstract away the change in meaning of @cdecl vs @_cdecl while
-  /// formalizing the attribute.
-  std::optional<ForeignLanguage> getCDeclKind() const;
-
   /// Determine whether the name of an argument is an API name by default
   /// depending on the function context.
   bool argumentNameIsAPIByDefault() const;

include/swift/AST/DeclAttr.def

@@ -365,10 +365,9 @@ SIMPLE_DECL_ATTR(_show_in_interface, ShowInInterface,
   62)
 
 DECL_ATTR(_cdecl, CDecl,
-  OnFunc | OnAccessor | OnEnum,
+  OnFunc | OnAccessor,
   LongAttribute | UserInaccessible | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove | ForbiddenInABIAttr,
   63)
-DECL_ATTR_ALIAS(cdecl, CDecl)
 
 SIMPLE_DECL_ATTR(usableFromInline, UsableFromInline,
   OnAbstractFunction | OnVar | OnSubscript | OnNominalType | OnTypeAlias,

include/swift/AST/DiagnosticsCommon.h

@@ -48,7 +48,6 @@ namespace swift {
   } // end namespace detail
 
   enum class StaticSpellingKind : uint8_t;
-  enum class ForeignLanguage : uint8_t;
 
   namespace diag {
 

include/swift/AST/DiagnosticsParse.def

@@ -1529,9 +1529,6 @@ ERROR(attr_expected_comma,none,
 ERROR(attr_expected_string_literal,none,
 "expected string literal in '%0' attribute", (StringRef))
 
-ERROR(attr_expected_cname,none,
-      "expected C identifier in '%0' attribute", (StringRef))
-
 ERROR(attr_expected_option_such_as,none,
       "expected '%0' option such as '%1'", (StringRef, StringRef))
 

include/swift/AST/DiagnosticsSema.def

@@ -2051,17 +2051,11 @@ WARNING(wrap_objc_implementation_will_become_error,none,
         (DiagnosticInfo *))
 
 ERROR(cdecl_not_at_top_level,none,
-      "%0 can only be applied to global functions", (DeclAttribute))
+      "@_cdecl can only be applied to global functions", ())
 ERROR(cdecl_empty_name,none,
-      "%0 symbol name cannot be empty", (DeclAttribute))
+      "@_cdecl symbol name cannot be empty", ())
 ERROR(cdecl_throws,none,
-      "raising errors from %0 functions is not supported", (DeclAttribute))
-ERROR(cdecl_incompatible_with_objc,none,
-      "cannot apply both '@cdecl' and '@objc' to %kindonly0",
-      (const Decl *))
-ERROR(cdecl_feature_required,none,
-      "@cdecl requires '-enable-experimental-feature CDecl'",
-      ())
+      "raising errors from '@_cdecl' functions is not supported", ())
 
 // @_used and @_section
 ERROR(section_linkage_markers_disabled,none,
@@ -3742,9 +3736,9 @@ ERROR(enum_with_raw_type_case_with_argument,none,
 NOTE(enum_raw_type_here,none,
      "declared raw type %0 here", (Type))
 ERROR(objc_enum_no_raw_type,none,
-      "'%0' enum must declare an integer raw type", (DeclAttribute))
+      "'@objc' enum must declare an integer raw type", ())
 ERROR(objc_enum_raw_type_not_integer,none,
-      "'%0' enum raw type %1 is not an integer type", (DeclAttribute, Type))
+      "'@objc' enum raw type %0 is not an integer type", (Type))
 ERROR(enum_non_integer_raw_value_auto_increment,none,
       "enum case must declare a raw value when the preceding raw value is not an integer", ())
 ERROR(enum_non_integer_convertible_raw_type_no_value,none,
@@ -5519,14 +5513,10 @@ FIXIT(insert_globalactor_attr, "@%0 ", (Type))
 ERROR(main_function_must_be_mainActor,none,
       "main() must be '@MainActor'", ())
 
-// Keep aligned with enum ForeignLanguage
-#define FOREIGN_LANG_SELECT "select{C|Objective-C}"
-
 ERROR(not_objc_function_async,none,
       "'async' %0 cannot be represented in Objective-C", (DescriptiveDeclKind))
 NOTE(not_objc_function_type_async,none,
-     "'async' function types cannot be represented "
-     "in %" FOREIGN_LANG_SELECT "0", (ForeignLanguage))
+      "'async' function types cannot be represented in Objective-C", ())
 ERROR(actor_isolated_objc,none,
       "actor-isolated %kind0 cannot be '@objc'",
        (const ValueDecl *))
@@ -6533,7 +6523,7 @@ ERROR(objc_cannot_infer_name_raw_identifier,none,
       (DescriptiveDeclKind))
 
 // If you change this, also change enum ObjCReason
-#define OBJC_ATTR_SELECT "select{marked '@cdecl'|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 '@objc @implementation' extension of a class (without final or '@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 '@objc @implementation' extension of a class (without final or '@nonobjc')|marked '@objc' by an access note}"
 
 ERROR(objc_invalid_on_var,none,
       "property cannot be %" OBJC_ATTR_SELECT "0 "
@@ -6566,36 +6556,25 @@ NOTE(not_objc_error_protocol_composition,none,
      "protocol-constrained type containing 'Error' cannot be represented "
      "in Objective-C", ())
 NOTE(not_objc_empty_tuple,none,
-     "empty tuple type cannot be represented in %" FOREIGN_LANG_SELECT "0",
-     (ForeignLanguage))
+      "empty tuple type cannot be represented in Objective-C", ())
 NOTE(not_objc_non_trivial_cxx_class,none,
-     "non-trivial C++ classes cannot be represented in "
-     "%" FOREIGN_LANG_SELECT "0",
-     (ForeignLanguage))
+     "non-trivial C++ classes cannot be represented in Objective-C", ())
 NOTE(not_objc_tuple,none,
-     "tuples cannot be represented in %" FOREIGN_LANG_SELECT "0",
-     (ForeignLanguage))
+      "tuples cannot be represented in Objective-C", ())
 NOTE(not_objc_swift_class,none,
      "classes not annotated with '@objc' cannot be represented "
      "in Objective-C", ())
 NOTE(not_objc_swift_struct,none,
-      "Swift structs cannot be represented in %" FOREIGN_LANG_SELECT "0",
-     (ForeignLanguage))
+      "Swift structs cannot be represented in Objective-C", ())
 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 '@cdecl'%select{| or '@objc'}0 cannot be "
-     "represented in %" FOREIGN_LANG_SELECT "0",
-     (ForeignLanguage))
 NOTE(not_objc_generic_type_param,none,
-     "generic type parameters cannot be represented in "
-     "%" FOREIGN_LANG_SELECT "0", (ForeignLanguage))
+     "generic type parameters cannot be represented in Objective-C", ())
 NOTE(not_objc_function_type_param,none,
-     "function types cannot be represented in %" FOREIGN_LANG_SELECT "0 "
-     "unless their parameters and returns can be", (ForeignLanguage))
+     "function types cannot be represented in Objective-C unless their "
+     "parameters and returns can be", ())
 NOTE(not_objc_function_type_throwing,none,
-     "throwing function types cannot be represented in "
-     "%" FOREIGN_LANG_SELECT "0", (ForeignLanguage))
+      "throwing function types cannot be represented in Objective-C", ())
 NOTE(objc_inferring_on_objc_protocol_member,none,
      "inferring '@objc' because the declaration is a member of "
      "an '@objc' protocol", ())
@@ -6605,11 +6584,6 @@ NOTE(objc_witness_objc_requirement,none,
      "satisfying requirement for %kind0 in protocol %1",
      (const ValueDecl *, const ProtocolDecl *))
 
-NOTE(cdecl_incompatible_with_protocols,none,
-     "protocols cannot be represented in C", ())
-NOTE(cdecl_incompatible_with_classes,none,
-     "classes cannot be represented in C", ())
-
 ERROR(no_opaque_return_type_of,none,
       "unable to resolve type for _opaqueReturnTypeOf attribute", ())
 
@@ -6622,24 +6596,20 @@ ERROR(objc_addressor, none,
 ERROR(objc_coroutine_accessor, none,
       "'read' and 'modify' accessors are not allowed to be marked '@objc'", ())
 ERROR(objc_invalid_on_func_variadic,none,
-      "%kindonly0 cannot be %" OBJC_ATTR_SELECT "1 because it has a variadic "
-      "parameter", (const AbstractFunctionDecl*, unsigned))
+      "method cannot be %" OBJC_ATTR_SELECT "0 because it has a variadic "
+      "parameter", (unsigned))
 ERROR(objc_invalid_on_func_inout,none,
-      "%kindonly0 cannot be %" OBJC_ATTR_SELECT "1 because inout "
-      "parameters cannot be represented in %" FOREIGN_LANG_SELECT "2",
-      (const AbstractFunctionDecl*, unsigned, ForeignLanguage))
+      "method cannot be %" OBJC_ATTR_SELECT "0 because inout "
+      "parameters cannot be represented in Objective-C", (unsigned))
 ERROR(objc_invalid_on_func_param_type,none,
-      "%kindonly0 cannot be %" OBJC_ATTR_SELECT "2 because the type of the "
-      "parameter %1 cannot be represented in %" FOREIGN_LANG_SELECT "3",
-      (const AbstractFunctionDecl*, unsigned, unsigned, ForeignLanguage))
+      "method cannot be %" OBJC_ATTR_SELECT "1 because the type of the "
+      "parameter %0 cannot be represented in Objective-C", (unsigned, unsigned))
 ERROR(objc_invalid_on_func_single_param_type,none,
-      "%kindonly0 cannot be %" OBJC_ATTR_SELECT "1 because the type of the "
-      "parameter cannot be represented in %" FOREIGN_LANG_SELECT "2",
-      (const AbstractFunctionDecl*, unsigned, ForeignLanguage))
+      "method cannot be %" OBJC_ATTR_SELECT "0 because the type of the "
+      "parameter cannot be represented in Objective-C", (unsigned))
 ERROR(objc_invalid_on_func_result_type,none,
-      "%kindonly0 cannot be %" OBJC_ATTR_SELECT "1 because its result type "
-      "cannot be represented in %" FOREIGN_LANG_SELECT "2",
-      (const AbstractFunctionDecl*, unsigned, ForeignLanguage))
+      "method cannot be %" OBJC_ATTR_SELECT "0 because its result type "
+      "cannot be represented in Objective-C", (unsigned))
 ERROR(objc_invalid_on_foreign_class,none,
       "method cannot be %" OBJC_ATTR_SELECT "0 because Core Foundation "
       "types are not classes in Objective-C", (unsigned))
@@ -6765,7 +6735,6 @@ ERROR(nonobjc_not_allowed,none,
 #undef OBJC_DIAG_SELECT_2
 #undef OBJC_DIAG_SELECT
 #undef OBJC_ATTR_SELECT
-#undef FOREIGN_LANG_SELECT
 
 //------------------------------------------------------------------------------
 // MARK: @exclusivity

include/swift/AST/Type.h

@@ -161,7 +161,7 @@ inline SubstOptions operator|(SubstFlags lhs, SubstFlags rhs) {
 
 /// Enumeration describing foreign languages to which Swift may be
 /// bridged.
-enum class ForeignLanguage : uint8_t {
+enum class ForeignLanguage {
   C,
   ObjectiveC,
 };

include/swift/AST/TypeCheckRequests.h

@@ -4875,44 +4875,6 @@ class TypeCheckObjCImplementationRequest
   bool isCached() const { return true; }
 };
 
-/// Check @cdecl functions for compatibility with the foreign language.
-class TypeCheckCDeclFunctionRequest
-    : public SimpleRequest<TypeCheckCDeclFunctionRequest,
-                           evaluator::SideEffect(FuncDecl *FD,
-                                                 CDeclAttr *attr),
-                           RequestFlags::Cached> {
-public:
-  using SimpleRequest::SimpleRequest;
-
-private:
-  friend SimpleRequest;
-
-  evaluator::SideEffect
-  evaluate(Evaluator &evaluator, FuncDecl *FD, CDeclAttr *attr) const;
-
-public:
-  bool isCached() const { return true; }
-};
-
-/// Check @cdecl enums for compatibility with C.
-class TypeCheckCDeclEnumRequest
-    : public SimpleRequest<TypeCheckCDeclEnumRequest,
-                           evaluator::SideEffect(EnumDecl *ED,
-                                                 CDeclAttr *attr),
-                           RequestFlags::Cached> {
-public:
-  using SimpleRequest::SimpleRequest;
-
-private:
-  friend SimpleRequest;
-
-  evaluator::SideEffect
-  evaluate(Evaluator &evaluator, EnumDecl *ED, CDeclAttr *attr) const;
-
-public:
-  bool isCached() const { return true; }
-};
-
 void simple_display(llvm::raw_ostream &out, ASTNode node);
 void simple_display(llvm::raw_ostream &out, Type value);
 void simple_display(llvm::raw_ostream &out, const TypeRepr *TyR);

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -554,12 +554,6 @@ SWIFT_REQUEST(TypeChecker, IsNonUserModuleRequest,
 SWIFT_REQUEST(TypeChecker, TypeCheckObjCImplementationRequest,
               unsigned(ExtensionDecl *),
               Cached, NoLocationInfo)
-SWIFT_REQUEST(TypeChecker, TypeCheckCDeclFunctionRequest,
-              evaluator::SideEffect(FunctionDecl *, CDeclAttr *),
-              Cached, NoLocationInfo)
-SWIFT_REQUEST(TypeChecker, TypeCheckCDeclEnumRequest,
-              evaluator::SideEffect(EnumDecl *, CDeclAttr *),
-              Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, HasInitAccessorRequest,
               bool(AbstractStorageDecl *), Cached,
               NoLocationInfo)

include/swift/Basic/Features.def

@@ -520,9 +520,6 @@ EXPERIMENTAL_FEATURE(ClosureBodyMacro, true)
 /// Allow declarations of Swift runtime symbols using @_silgen_name.
 EXPERIMENTAL_FEATURE(AllowRuntimeSymbolDeclarations, true)
 
-/// Allow use of `@cdecl`
-EXPERIMENTAL_FEATURE(CDecl, true)
-
 /// Optimize copies of ObjectiveC blocks.
 EXPERIMENTAL_FEATURE(CopyBlockOptimization, true)
 

include/swift/PrintAsClang/ClangMacros.def

@@ -176,46 +176,20 @@ CLANG_MACRO_CONDITIONAL("SWIFT_ENUM_ATTR", "(_extensibility)", \
                         "__attribute__((enum_extensibility(_extensibility)))")
 
 CLANG_MACRO_BODY("SWIFT_ENUM", \
-    "# if (defined(__cplusplus) && __cplusplus >= 201103L) || " \
-    "     (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || " \
-    "     __has_feature(objc_fixed_enum)\n" \
-    "#  define SWIFT_ENUM(_type, _name, _extensibility) " \
+    "# define SWIFT_ENUM(_type, _name, _extensibility) " \
         "enum _name : _type _name; " \
         "enum SWIFT_ENUM_ATTR(_extensibility) SWIFT_ENUM_EXTRA _name : _type\n" \
-    "#  if __has_feature(generalized_swift_name)\n" \
-    "#   define SWIFT_ENUM_NAMED(_type, _name, SWIFT_NAME, _extensibility) " \
-         "enum _name : _type _name SWIFT_COMPILE_NAME(SWIFT_NAME); " \
-         "enum SWIFT_COMPILE_NAME(SWIFT_NAME) SWIFT_ENUM_ATTR(_extensibility) " \
-             "SWIFT_ENUM_EXTRA _name : _type\n" \
-    "#  else\n" \
-    "#   define SWIFT_ENUM_NAMED(_type, _name, SWIFT_NAME, _extensibility) " \
-         "SWIFT_ENUM(_type, _name, _extensibility)\n" \
-    "#  endif\n" \
+    "# if __has_feature(generalized_swift_name)\n" \
+    "#  define SWIFT_ENUM_NAMED(_type, _name, SWIFT_NAME, _extensibility) " \
+        "enum _name : _type _name SWIFT_COMPILE_NAME(SWIFT_NAME); " \
+        "enum SWIFT_COMPILE_NAME(SWIFT_NAME) SWIFT_ENUM_ATTR(_extensibility) " \
+            "SWIFT_ENUM_EXTRA _name : _type\n" \
     "# else\n" \
-    "#  define SWIFT_ENUM(_type, _name, _extensibility) _type _name; enum \n" \
     "#  define SWIFT_ENUM_NAMED(_type, _name, SWIFT_NAME, _extensibility) " \
         "SWIFT_ENUM(_type, _name, _extensibility)\n" \
     "# endif")
 CLANG_MACRO_DEFINED("SWIFT_ENUM_NAMED")
 
-CLANG_MACRO_BODY("SWIFT_ENUM_TAG", \
-    "# if (defined(__cplusplus) && __cplusplus >= 201103L) || " \
-    "     (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || " \
-    "     __has_feature(objc_fixed_enum)\n" \
-    "#  define SWIFT_ENUM_TAG enum\n" \
-    "# else\n" \
-    "#  define SWIFT_ENUM_TAG\n" \
-    "# endif")
-
-CLANG_MACRO_BODY("SWIFT_ENUM_FWD_DECL", \
-    "# if (defined(__cplusplus) && __cplusplus >= 201103L) || " \
-    "     (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) || " \
-    "     __has_feature(objc_fixed_enum)\n" \
-    "#  define SWIFT_ENUM_FWD_DECL(_type, _name) enum _name : _type _name;\n" \
-    "# else\n" \
-    "#  define SWIFT_ENUM_FWD_DECL(_type, _name) _type _name;\n" \
-    "# endif")
-
 CLANG_MACRO("SWIFT_UNAVAILABLE", , "__attribute__((unavailable))")
 CLANG_MACRO("SWIFT_UNAVAILABLE_MSG", "(msg)", "__attribute__((unavailable(msg)))")
 

lib/AST/Attr.cpp

@@ -1799,9 +1799,7 @@ StringRef DeclAttribute::getAttrName() const {
   case DeclAttrKind::Alignment:
     return "_alignment";
   case DeclAttrKind::CDecl:
-    if (cast<CDeclAttr>(this)->Underscored)
-      return "_cdecl";
-    return "cdecl";
+    return "_cdecl";
   case DeclAttrKind::SwiftNativeObjCRuntimeBase:
     return "_swift_native_objc_runtime_base";
   case DeclAttrKind::Semantics: