Parser: Rename the experimental attribute @cdecl to the shorter @c

include/swift/AST/Decl.h

@@ -4903,12 +4903,12 @@ class EnumDecl final : public NominalTypeDecl {
     return getAttrs().hasAttribute<IndirectAttr>();
   }
 
-  /// True if the enum is marked with `@cdecl`.
+  /// True if the enum is marked with `@c`.
   bool isCDeclEnum() const {
     return getAttrs().hasAttribute<CDeclAttr>();
   }
 
-  /// True if the enum is marked with `@cdecl` or `@objc`.
+  /// True if the enum is marked with `@c` or `@objc`.
   bool isCCompatibleEnum() const {
     return isCDeclEnum() || isObjC();
   }
@@ -8236,8 +8236,8 @@ 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
+  /// Get the foreign language targeted by a @c-style attribute, if any.
+  /// Used to abstract away the change in meaning of @c vs @_cdecl while
   /// formalizing the attribute.
   std::optional<ForeignLanguage> getCDeclKind() const;
 

include/swift/AST/DeclAttr.def

@@ -368,11 +368,11 @@ SIMPLE_DECL_ATTR(_show_in_interface, ShowInInterface,
   UserInaccessible | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove | UnreachableInABIAttr,
   62)
 
-DECL_ATTR(_cdecl, CDecl,
+DECL_ATTR(c, CDecl,
   OnFunc | OnAccessor | OnEnum,
   LongAttribute | UserInaccessible | ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove | ForbiddenInABIAttr,
   63)
-DECL_ATTR_ALIAS(cdecl, CDecl)
+DECL_ATTR_ALIAS(_cdecl, CDecl)
 
 SIMPLE_DECL_ATTR(usableFromInline, UsableFromInline,
   OnAbstractFunction | OnVar | OnSubscript | OnNominalType | OnTypeAlias,

include/swift/AST/DiagnosticsSema.def

@@ -2089,10 +2089,10 @@ ERROR(cdecl_empty_name,none,
 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",
+      "cannot apply both '@c' and '@objc' to %kindonly0",
       (const Decl *))
 ERROR(cdecl_feature_required,none,
-      "'@cdecl' requires '-enable-experimental-feature CDecl'",
+      "'@c' requires '-enable-experimental-feature CDecl'",
       ())
 
 // @_used and @_section
@@ -6617,7 +6617,7 @@ ERROR(objc_cannot_infer_name_raw_identifier,none,
       (const ValueDecl *))
 
 // 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 '@c'|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 "
@@ -6671,7 +6671,7 @@ NOTE(not_objc_swift_struct,none,
 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 "
+     "Swift enums not marked '@c'%select{| or '@objc'}0 cannot be "
      "represented in %" FOREIGN_LANG_SELECT "0",
      (ForeignLanguage))
 NOTE(not_objc_generic_type_param,none,

include/swift/AST/TypeCheckRequests.h

@@ -4948,7 +4948,7 @@ class TypeCheckObjCImplementationRequest
   bool isCached() const { return true; }
 };
 
-/// Check @cdecl functions for compatibility with the foreign language.
+/// Check @c functions for compatibility with the foreign language.
 class TypeCheckCDeclFunctionRequest
     : public SimpleRequest<TypeCheckCDeclFunctionRequest,
                            evaluator::SideEffect(FuncDecl *FD,
@@ -4967,7 +4967,7 @@ class TypeCheckCDeclFunctionRequest
   bool isCached() const { return true; }
 };
 
-/// Check @cdecl enums for compatibility with C.
+/// Check @c enums for compatibility with C.
 class TypeCheckCDeclEnumRequest
     : public SimpleRequest<TypeCheckCDeclEnumRequest,
                            evaluator::SideEffect(EnumDecl *ED,

include/swift/Basic/Features.def

@@ -529,7 +529,7 @@ EXPERIMENTAL_FEATURE(ClosureBodyMacro, true)
 /// Allow declarations of Swift runtime symbols using @_silgen_name.
 EXPERIMENTAL_FEATURE(AllowRuntimeSymbolDeclarations, true)
 
-/// Allow use of `@cdecl`
+/// Allow use of `@c`
 EXPERIMENTAL_FEATURE(CDecl, false)
 
 /// Allow use of `Module::name` syntax

lib/AST/Attr.cpp

@@ -1246,9 +1246,17 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
     break;
   }
 
-  case DeclAttrKind::CDecl:
-    Printer << "@_cdecl(\"" << cast<CDeclAttr>(this)->Name << "\")";
+  case DeclAttrKind::CDecl: {
+    auto Attr = cast<CDeclAttr>(this);
+    if (Attr->Underscored)
+      Printer << "@_cdecl(\"" << cast<CDeclAttr>(this)->Name << "\")";
+    else {
+      Printer << "@c";
+      if (!Attr->Name.empty())
+        Printer << "(" << cast<CDeclAttr>(this)->Name << ")";
+    }
     break;
+  }
 
   case DeclAttrKind::Expose: {
     Printer.printAttrName("@_expose");
@@ -1825,7 +1833,7 @@ StringRef DeclAttribute::getAttrName() const {
   case DeclAttrKind::CDecl:
     if (cast<CDeclAttr>(this)->Underscored)
       return "_cdecl";
-    return "cdecl";
+    return "c";
   case DeclAttrKind::SwiftNativeObjCRuntimeBase:
     return "_swift_native_objc_runtime_base";
   case DeclAttrKind::Semantics:

lib/AST/ClangTypeConverter.cpp

@@ -655,7 +655,7 @@ clang::QualType ClangTypeConverter::visitEnumType(EnumType *type) {
 
   auto ED = type->getDecl();
   if (!ED->isCCompatibleEnum())
-    // Can't translate something not marked with @objc or @cdecl.
+    // Can't translate something not marked with @objc or @c.
     return clang::QualType();
 
   // @objc enums lower to their raw types.

lib/AST/Type.cpp

@@ -3166,7 +3166,7 @@ getForeignRepresentable(Type type, ForeignLanguage language,
       if (isa<ClassDecl>(nominal) || isa<ProtocolDecl>(nominal))
         return failure();
 
-      // @objc enums are not representable in C, @cdecl ones and imported ones
+      // @objc enums are not representable in C, @c ones and imported ones
       // are ok.
       if (!nominal->hasClangNode())
         return failure();
@@ -3209,7 +3209,7 @@ getForeignRepresentable(Type type, ForeignLanguage language,
     }
   }
 
-  // @cdecl enums are representable in C and Objective-C.
+  // @c enums are representable in C and Objective-C.
   if (nominal->getAttrs().getAttribute<CDeclAttr>()) {
     return { ForeignRepresentableKind::Trivial, nullptr };
   }

lib/IRGen/GenEnum.cpp

@@ -6536,7 +6536,7 @@ EnumImplStrategy::get(TypeConverter &TC, SILType type, EnumDecl *theEnum) {
         std::move(elementsWithPayload), std::move(elementsWithNoPayload)));
   }
 
-  // Enums imported from Clang or marked with @objc or @cdecl use a
+  // Enums imported from Clang or marked with @objc or @c use a
   // C-compatible layout.
   if (theEnum->hasClangNode() || theEnum->isCCompatibleEnum()) {
     assert(elementsWithPayload.empty() && "C enum with payload?!");

lib/Parse/ParseDecl.cpp

@@ -3026,7 +3026,7 @@ ParserStatus Parser::parseNewDeclAttribute(DeclAttributes &Attributes,
   case DeclAttrKind::CDecl: {
     if (!AttrName.starts_with("_") &&
 
-        // Backwards support for @cdecl("stringId"). Remove before enabling in
+        // Backwards support for @c("stringId"). Remove before enabling in
         // production so we accept only the identifier format.
         lookahead<bool>(1, [&](CancellableBacktrackingScope &) {
            return Tok.isNot(tok::string_literal);

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -2418,7 +2418,7 @@ class DeclAndTypePrinter::Implementation
     if (ED && !NTD->hasClangNode()) {
       if (ED->isCDeclEnum()) {
         // We should be able to use the tag macro for all printed enums but
-        // for now restrict it to @cdecl to guard it behind the feature flag.
+        // for now restrict it to @c to guard it behind the feature flag.
         os << "SWIFT_ENUM_TAG ";
       } else {
         os << "enum ";
@@ -3056,7 +3056,7 @@ bool DeclAndTypePrinter::shouldInclude(const ValueDecl *VD) {
       return false;
   }
 
-  // In C output mode print only the C variant `@cdecl` (no `@_cdecl`),
+  // In C output mode print only the C variant `@c` (no `@_cdecl`),
   // while in other modes print only `@_cdecl`.
   std::optional<ForeignLanguage> cdeclKind = std::nullopt;
   if (auto *FD = dyn_cast<AbstractFunctionDecl>(VD))
@@ -3066,14 +3066,14 @@ bool DeclAndTypePrinter::shouldInclude(const ValueDecl *VD) {
        (outputLang == OutputLanguageMode::C))
     return false;
 
-  // C output mode only prints @cdecl functions and enums.
+  // C output mode only prints @c functions and enums.
   if (outputLang == OutputLanguageMode::C &&
       !cdeclKind && !isa<EnumDecl>(VD)) {
     return false;
   }
 
-  // The C mode prints @cdecl enums and reject other enums,
-  // while other modes accept other enums and reject @cdecl ones.
+  // The C mode prints @c enums and reject other enums,
+  // while other modes accept other enums and reject @c ones.
   if (isa<EnumDecl>(VD) &&
       VD->getAttrs().hasAttribute<CDeclAttr>() !=
         (outputLang == OutputLanguageMode::C)) {

lib/PrintAsClang/ModuleContentsWriter.cpp

@@ -460,7 +460,7 @@ class ModuleWriter {
 
     if (isa<EnumDecl>(D) && !D->hasClangNode() &&
         outputLangMode != OutputLanguageMode::Cxx) {
-      // We don't want to add an import for a @cdecl or @objc enum declared
+      // We don't want to add an import for a @c or @objc enum declared
       // in Swift. We either do nothing for special enums like Optional as
       // done in the prologue here, or we forward declare them.
       return false;

lib/PrintAsClang/PrintAsClang.cpp

@@ -615,7 +615,7 @@ bool swift::printAsClangHeader(raw_ostream &os, ModuleDecl *M,
   SwiftToClangInteropContext interopContext(*M, irGenOpts);
   writePrologue(os, M->getASTContext(), computeMacroGuard(M));
 
-  // C content (@cdecl)
+  // C content (@c)
   std::string moduleContentsScratch;
   if (M->getASTContext().LangOpts.hasFeature(Feature::CDecl)) {
     SmallPtrSet<ImportModuleTy, 8> imports;

lib/SIL/IR/SILFunctionBuilder.cpp

@@ -170,7 +170,7 @@ void SILFunctionBuilder::addFunctionAttributes(
   for (auto *EA : Attrs.getAttributes<ExposeAttr>()) {
     bool shouldExportDecl = true;
     if (Attrs.hasAttribute<CDeclAttr>()) {
-      // If the function is marked with @cdecl, expose only C compatible
+      // If the function is marked with @c, expose only C compatible
       // thunk function.
       shouldExportDecl = constant.isNativeToForeignThunk();
     }

lib/Sema/TypeCheckAttr.cpp

@@ -2446,12 +2446,12 @@ void AttributeChecker::visitCDeclAttr(CDeclAttr *attr) {
              attr, "func");
   }
 
-  // Reject using both @cdecl and @objc on the same decl.
+  // Reject using both @c and @objc on the same decl.
   if (D->getAttrs().getAttribute<ObjCAttr>()) {
     diagnose(attr->getLocation(), diag::cdecl_incompatible_with_objc, D);
   }
 
-  // @cdecl needs to be enabled via a feature flag.
+  // @c needs to be enabled via a feature flag.
   if (!attr->Underscored &&
       !Ctx.LangOpts.hasFeature(Feature::CDecl)) {
     diagnose(attr->getLocation(), diag::cdecl_feature_required);

lib/Sema/TypeCheckDeclObjC.cpp

@@ -223,7 +223,7 @@ static void diagnoseTypeNotRepresentableInObjC(const DeclContext *DC,
   // Special diagnostic for enums.
   if (T->is<EnumType>()) {
     if (DC->getASTContext().LangOpts.hasFeature(Feature::CDecl)) {
-      // New dialog mentioning @cdecl.
+      // New dialog mentioning @c.
       diags.diagnose(TypeRange.Start, diag::not_cdecl_or_objc_swift_enum,
                      language)
           .highlight(TypeRange)
@@ -1782,13 +1782,13 @@ static bool isCIntegerType(Type type) {
 static bool isEnumObjC(EnumDecl *enumDecl, DeclAttribute *attr) {
   // FIXME: Use shouldMarkAsObjC once it loses it's TypeChecker argument.
 
-  // If there is no @objc or @cdecl attribute, skip it.
+  // If there is no @objc or @c attribute, skip it.
   if (!attr)
     return false;
 
   Type rawType = enumDecl->getRawType();
 
-  // @objc/@cdecl enums must have a raw type.
+  // @objc/@c enums must have a raw type.
   if (!rawType) {
     enumDecl->diagnose(diag::objc_enum_no_raw_type, attr);
     return false;
@@ -4227,7 +4227,7 @@ TypeCheckCDeclFunctionRequest::evaluate(Evaluator &evaluator,
   auto &ctx = FD->getASTContext();
 
   auto lang = FD->getCDeclKind();
-  assert(lang && "missing @cdecl?");
+  assert(lang && "missing @c?");
   auto kind = lang == ForeignLanguage::ObjectiveC
                       ? ObjCReason::ExplicitlyUnderscoreCDecl
                       : ObjCReason::ExplicitlyCDecl;

lib/Sema/TypeCheckObjC.h

@@ -41,7 +41,7 @@ class ObjCReason {
 public:
   // The kind of reason.
   enum Kind {
-    /// Has the '@cdecl' attribute.
+    /// Has the '@c' attribute.
     ExplicitlyCDecl,
     /// Has the '@_cdecl' attribute.
     ExplicitlyUnderscoreCDecl,

test/ASTGen/attrs.swift

@@ -99,8 +99,8 @@ func fn(_: Int) {}
 @_disallowFeatureSuppression(NoncopyableGenerics) public struct LoudlyNC<T: ~Copyable> {}
 
 @_cdecl("c_function_name") func cdeclUnderscore(x: Int) {}
-@cdecl(c_function_name_official) func cdecl(x: Int) {}
-@cdecl func cdeclDefault() {}
+@c(c_function_name_official) func cdecl(x: Int) {}
+@c func cdeclDefault() {}
 
 struct StaticProperties {
   dynamic var property: Int { return 1 }

test/IRGen/cdecl_implementation.swift

@@ -10,13 +10,13 @@
 // REQUIRES: swift_feature_CImplementation
 // REQUIRES: swift_feature_CDecl
 
-@implementation @cdecl
+@implementation @c
 public func implFunc(_ param: Int32) {}
 
-@implementation @cdecl
+@implementation @c
 public func implFuncCName(_ param: Int32) {}
 
-@implementation @cdecl(implFuncRenamed_C)
+@implementation @c(implFuncRenamed_C)
 public func implFuncRenamed_Swift(param: Int32) {}
 
 public func fn() {

test/Interpreter/cdecl_enum_run.swift

@@ -4,19 +4,19 @@
 // REQUIRES: swift_feature_CDecl
 // REQUIRES: executable_test
 
-@cdecl
+@c
 enum CDecl8: UInt8 {
 case a
 case b
 }
 
-@cdecl
+@c
 enum CDecl16: UInt16 {
 case a
 case b
 }
 
-@cdecl(SomeName)
+@c(SomeName)
 enum CDecl32: UInt32 {
 case a
 case b
@@ -33,12 +33,12 @@ case a
 case b
 }
 
-print("@cdecl enum 8 is \(MemoryLayout<CDecl8>.size) bytes")
-// CHECK: @cdecl enum 8 is 1 bytes
-print("@cdecl enum 16 is \(MemoryLayout<CDecl16>.size) bytes")
-// CHECK: @cdecl enum 16 is 2 bytes
-print("@cdecl enum 32 is \(MemoryLayout<CDecl32>.size) bytes")
-// CHECK: @cdecl enum 32 is 4 bytes
+print("@c enum 8 is \(MemoryLayout<CDecl8>.size) bytes")
+// CHECK: @c enum 8 is 1 bytes
+print("@c enum 16 is \(MemoryLayout<CDecl16>.size) bytes")
+// CHECK: @c enum 16 is 2 bytes
+print("@c enum 32 is \(MemoryLayout<CDecl32>.size) bytes")
+// CHECK: @c enum 32 is 4 bytes
 print("@objc enum is \(MemoryLayout<ObjCEnum>.size) bytes")
 // CHECK: @objc enum is 4 bytes
 print("Swift enum is \(MemoryLayout<SwiftEnum>.size) bytes")

test/Interpreter/cdecl_implementation_run.swift

@@ -44,23 +44,23 @@ extern void renamed_clangSide(ptrdiff_t arg);
 
 //--- Lib.swift
 
-@cdecl @implementation
+@c @implementation
 public func simple(_ x: Int32, _ y: Int32) -> Int32 {
     print(x, y)
     return x
 }
 
-@implementation @cdecl
+@implementation @c
 public func primitiveTypes(_ i: Int, _ ci: CInt, _ l: CLong, _ c: CChar, _ f: Float, _ d: Double, _ b: Bool) {
     print(i, ci, l, c, f, d, b)
 }
 
-@cdecl(sameName) @implementation
+@c(sameName) @implementation
 public func sameName() {
     print("sameName")
 }
 
-@cdecl(renamed_clangSide) @implementation
+@c(renamed_clangSide) @implementation
 public func renamed_swiftSide(_ arg: Int) {
     print(arg)
 }