Add underscore prefix to extern attribute

kateinoigakukun · kateinoigakukun · commit 79b3d2d62690 · 2023-11-07T02:01:02.000Z
It's already guarded by a feature flag, but it would be nice to signal
users that it's not stable yet by adding an underscore prefix.
diff --git a/docs/ReferenceGuides/UnderscoredAttributes.md b/docs/ReferenceGuides/UnderscoredAttributes.md
@@ -437,19 +437,19 @@ the export name.
 
 It's the equivalent of clang's `__attribute__((export_name))`.
 
-## `@extern(<language>)`
+## `@_extern(<language>)`
 
 Indicates that a particular declaration should be imported
 from the external environment.
 
-### `@extern(wasm, module: <"moduleName">, name: <"fieldName">)`
+### `@_extern(wasm, module: <"moduleName">, name: <"fieldName">)`
 
 Indicates that a particular declaration should be imported
 through WebAssembly's import interface.
 
 It's the equivalent of clang's `__attribute__((import_module("module"), import_name("field")))`.
 
-### `@extern(c, [, <"cName">])`
+### `@_extern(c, [, <"cName">])`
 
 Indicates that a particular declaration should refer to a
 C declaration with the given name. If the optional "cName"
@@ -462,7 +462,7 @@ C declarations from Swift, while `@_cdecl` is used to define
 Swift functions that can be referenced from C.
 
 Also similar to `@_silgen_name`, but a function declared with
-`@extern(c)` is assumed to use the C ABI, while `@_silgen_name`
+`@_extern(c)` is assumed to use the C ABI, while `@_silgen_name`
 assumes the Swift ABI.
 
 ## `@_fixed_layout`
diff --git a/include/swift/AST/Attr.def b/include/swift/AST/Attr.def
@@ -421,7 +421,7 @@ DECL_ATTR(_section, Section,
 DECL_ATTR(_rawLayout, RawLayout,
   OnStruct | UserInaccessible | ABIBreakingToAdd | ABIBreakingToRemove | APIStableToAdd | APIStableToRemove,
   146)
-DECL_ATTR(extern, Extern,
+DECL_ATTR(_extern, Extern,
   OnFunc | AllowMultipleAttributes | ABIBreakingToAdd | ABIBreakingToRemove | APIStableToAdd | APIStableToRemove,
   147)
 SIMPLE_DECL_ATTR(_nonEscapable, NonEscapable,
diff --git a/include/swift/AST/Attr.h b/include/swift/AST/Attr.h
@@ -2343,7 +2343,7 @@ class ExposeAttr : public DeclAttribute {
   }
 };
 
-/// Define the `@extern` attribute, used to import external declarations in
+/// Define the `@_extern` attribute, used to import external declarations in
 /// the specified way to interoperate with Swift.
 class ExternAttr : public DeclAttribute {
   SourceLoc LParenLoc, RParenLoc;
@@ -2368,7 +2368,7 @@ class ExternAttr : public DeclAttribute {
   const llvm::Optional<StringRef> ModuleName;
 
   /// The declaration name to import
-  /// std::nullopt if the declaration name is not specified with @extern(c)
+  /// std::nullopt if the declaration name is not specified with @_extern(c)
   const llvm::Optional<StringRef> Name;
 
   SourceLoc getLParenLoc() const { return LParenLoc; }
diff --git a/include/swift/AST/AttrKind.h b/include/swift/AST/AttrKind.h
@@ -112,7 +112,7 @@ enum class ExposureKind: uint8_t {
 enum : unsigned { NumExposureKindBits =
   countBitsUsed(static_cast<unsigned>(ExposureKind::Last_ExposureKind)) };
   
-/// This enum represents the possible values of the @extern attribute.
+/// This enum represents the possible values of the @_extern attribute.
 enum class ExternKind: uint8_t {
   /// Reference an externally defined C function.
   /// The imported function has C function pointer representation,
diff --git a/include/swift/AST/DiagnosticsParse.def b/include/swift/AST/DiagnosticsParse.def
@@ -1869,7 +1869,7 @@ ERROR(attr_rawlayout_expected_params,none,
       "expected %1 argument after %0 argument in @_rawLayout attribute", (StringRef, StringRef))
 
 ERROR(attr_extern_expected_label,none,
-      "expected %0 argument to @extern attribute", (StringRef))
+      "expected %0 argument to @_extern attribute", (StringRef))
 //------------------------------------------------------------------------------
 // MARK: Generics parsing diagnostics
 //------------------------------------------------------------------------------
diff --git a/include/swift/AST/DiagnosticsSema.def b/include/swift/AST/DiagnosticsSema.def
@@ -1900,17 +1900,17 @@ ERROR(section_not_at_top_level,none,
 ERROR(section_empty_name,none,
       "@_section section name cannot be empty", ())
 
-// @extern
+// @_extern
 ERROR(attr_extern_experimental,none,
-      "@extern requires '-enable-experimental-feature Extern'", ())
+      "@_extern requires '-enable-experimental-feature Extern'", ())
 ERROR(extern_not_at_top_level_func,none,
-      "@extern attribute can only be applied to global functions", ())
+      "@_extern attribute can only be applied to global functions", ())
 ERROR(extern_empty_c_name,none,
-      "expected non-empty C name in @extern attribute", ())
+      "expected non-empty C name in @_extern attribute", ())
 ERROR(extern_only_non_other_attr,none,
-      "@extern attribute cannot be applied to an '@%0' declaration", (StringRef))
+      "@_extern attribute cannot be applied to an '@%0' declaration", (StringRef))
 WARNING(extern_c_maybe_invalid_name, none,
-        "C name '%0' may be invalid; explicitly specify the name in @extern(c) to suppress this warning",
+        "C name '%0' may be invalid; explicitly specify the name in @_extern(c) to suppress this warning",
         (StringRef))
 
 ERROR(c_func_variadic, none,
diff --git a/include/swift/Basic/Features.def b/include/swift/Basic/Features.def
@@ -257,7 +257,7 @@ EXPERIMENTAL_FEATURE(StructLetDestructuring, true)
 /// lifetime-dependent results.
 EXPERIMENTAL_FEATURE(NonEscapableTypes, false)
 
-/// Enable the `@extern` attribute.
+/// Enable the `@_extern` attribute.
 EXPERIMENTAL_FEATURE(Extern, true)
 
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
diff --git a/include/swift/Parse/Parser.h b/include/swift/Parse/Parser.h
@@ -1095,7 +1095,7 @@ class Parser {
   ParserResult<DifferentiableAttr> parseDifferentiableAttribute(SourceLoc AtLoc,
                                                                 SourceLoc Loc);
 
-  /// Parse the @extern attribute.
+  /// Parse the @_extern attribute.
   bool parseExternAttribute(DeclAttributes &Attributes, bool &DiscardAttribute,
                             StringRef AttrName, SourceLoc AtLoc, SourceLoc Loc);
 
diff --git a/include/swift/SIL/SILFunction.h b/include/swift/SIL/SILFunction.h
@@ -303,7 +303,7 @@ class SILFunction
   /// empty.
   StringRef WasmExportName;
 
-  /// Name of a Wasm import module and field if @extern(wasm) attribute
+  /// Name of a Wasm import module and field if @_extern(wasm) attribute
   llvm::Optional<std::pair<StringRef, StringRef>> WasmImportModuleAndField;
 
   /// Has value if there's a profile for this function
@@ -1288,14 +1288,14 @@ class SILFunction
   StringRef wasmExportName() const { return WasmExportName; }
   void setWasmExportName(StringRef value) { WasmExportName = value; }
 
-  /// Return Wasm import module name if @extern(wasm) was used otherwise empty
+  /// Return Wasm import module name if @_extern(wasm) was used otherwise empty
   StringRef wasmImportModuleName() const {
     if (WasmImportModuleAndField)
       return WasmImportModuleAndField->first;
     return StringRef();
   }
 
-  /// Return Wasm import field name if @extern(wasm) was used otherwise empty
+  /// Return Wasm import field name if @_extern(wasm) was used otherwise empty
   StringRef wasmImportFieldName() const {
     if (WasmImportModuleAndField)
       return WasmImportModuleAndField->second;
diff --git a/lib/AST/Attr.cpp b/lib/AST/Attr.cpp
@@ -1144,7 +1144,7 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
 
   case DAK_Extern: {
     auto *Attr = cast<ExternAttr>(this);
-    Printer.printAttrName("@extern");
+    Printer.printAttrName("@_extern");
     Printer << "(";
     switch (Attr->getExternKind()) {
     case ExternKind::C:
@@ -1155,7 +1155,7 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
       break;
     case ExternKind::Wasm:
       Printer << "wasm";
-      // @extern(wasm) always has names.
+      // @_extern(wasm) always has names.
       Printer << ", module: \"" << *Attr->ModuleName << "\"";
       Printer << ", name: \"" << *Attr->Name << "\"";
       break;
@@ -1749,7 +1749,7 @@ StringRef DeclAttribute::getAttrName() const {
   case DAK_RawLayout:
     return "_rawLayout";
   case DAK_Extern:
-    return "extern";
+    return "_extern";
   }
   llvm_unreachable("bad DeclAttrKind");
 }
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
@@ -1436,7 +1436,7 @@ bool Parser::parseExternAttribute(DeclAttributes &Attributes,
                                   SourceLoc AtLoc, SourceLoc Loc) {
   SourceLoc lParenLoc = Tok.getLoc(), rParenLoc;
 
-  // Parse @extern(<language>, ...)
+  // Parse @_extern(<language>, ...)
   if (!consumeIf(tok::l_paren)) {
     diagnose(Loc, diag::attr_expected_lparen, AttrName,
              DeclAttribute::isDeclModifier(DAK_Extern));
@@ -1488,7 +1488,7 @@ bool Parser::parseExternAttribute(DeclAttributes &Attributes,
   auto kindTok = Tok;
   consumeToken(tok::identifier);
 
-  // Parse @extern(wasm, module: "x", name: "y") or @extern(c[, "x"])
+  // Parse @_extern(wasm, module: "x", name: "y") or @_extern(c[, "x"])
   ExternKind kind;
   llvm::Optional<StringRef> importModuleName, importName;
 
diff --git a/lib/SIL/IR/SILDeclRef.cpp b/lib/SIL/IR/SILDeclRef.cpp
@@ -1149,7 +1149,7 @@ std::string SILDeclRef::mangle(ManglingKind MKind) const {
       }
 
     if (auto *ExternA = ExternAttr::find(getDecl()->getAttrs(), ExternKind::C)) {
-      assert(isa<FuncDecl>(getDecl()) && "non-FuncDecl with @extern should be rejected by typechecker");
+      assert(isa<FuncDecl>(getDecl()) && "non-FuncDecl with @_extern should be rejected by typechecker");
       return ExternA->getCName(cast<FuncDecl>(getDecl())).str();
     }
 
diff --git a/lib/SIL/IR/SILFunctionBuilder.cpp b/lib/SIL/IR/SILFunctionBuilder.cpp
@@ -181,7 +181,7 @@ void SILFunctionBuilder::addFunctionAttributes(
   }
 
   if (auto *EA = ExternAttr::find(Attrs, ExternKind::Wasm)) {
-    // @extern(wasm) always has explicit names
+    // @_extern(wasm) always has explicit names
     F->setWasmImportModuleAndField(*EA->ModuleName, *EA->Name);
   }
 
diff --git a/lib/Sema/TypeCheckAttr.cpp b/lib/Sema/TypeCheckAttr.cpp
@@ -2173,7 +2173,7 @@ void AttributeChecker::visitExternAttr(ExternAttr *attr) {
   }
 
   for (auto *otherAttr : D->getAttrs()) {
-    // @_cdecl cannot be mixed with @extern since @_cdecl is for definitions
+    // @_cdecl cannot be mixed with @_extern since @_cdecl is for definitions
     // @_silgen_name cannot be mixed to avoid SIL-level name ambiguity
     if (isa<CDeclAttr>(otherAttr) || isa<SILGenNameAttr>(otherAttr)) {
       diagnose(attr->getLocation(), diag::extern_only_non_other_attr,
diff --git a/lib/Sema/TypeCheckDeclPrimary.cpp b/lib/Sema/TypeCheckDeclPrimary.cpp
@@ -3440,7 +3440,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
   /// Determine whether the given declaration should not have a definition.
   static bool requiresNoDefinition(Decl *decl) {
     if (auto func = dyn_cast<AbstractFunctionDecl>(decl)) {
-      // Function with @extern should not have a body.
+      // Function with @_extern should not have a body.
       return func->getAttrs().hasAttribute<ExternAttr>();
     }
     // Everything else can have a definition.
diff --git a/test/IDE/complete_decl_attribute.swift b/test/IDE/complete_decl_attribute.swift
@@ -109,7 +109,6 @@ actor MyGenericGlobalActor<T> {
 // KEYWORD2-NEXT:             Keyword/None:                       Sendable[#Func Attribute#]; name=Sendable
 // KEYWORD2-NEXT:             Keyword/None:                       preconcurrency[#Func Attribute#]; name=preconcurrency
 // KEYWORD2-NEXT:             Keyword/None:                       backDeployed[#Func Attribute#]; name=backDeployed
-// KEYWORD2-NEXT:             Keyword/None:                       extern[#Func Attribute#]; name=extern
 // KEYWORD2-NOT:              Keyword
 // KEYWORD2-DAG:              Decl[Struct]/CurrModule:            MyStruct[#MyStruct#]; name=MyStruct
 // KEYWORD2-DAG:              Decl[Struct]/CurrModule:            MyPropertyWrapper[#Property Wrapper#]; name=MyPropertyWrapper
@@ -249,7 +248,6 @@ struct _S {
 // ON_METHOD-DAG: Keyword/None:                       noDerivative[#Func Attribute#]; name=noDerivative
 // ON_METHOD-DAG: Keyword/None:                       preconcurrency[#Func Attribute#]; name=preconcurrency
 // ON_METHOD-DAG: Keyword/None:                       backDeployed[#Func Attribute#]; name=backDeployed
-// ON_METHOD-DAG: Keyword/None:                       extern[#Func Attribute#]; name=extern
 // ON_METHOD-NOT: Keyword
 // ON_METHOD-DAG: Decl[Struct]/CurrModule:            MyStruct[#MyStruct#]; name=MyStruct
 // ON_METHOD-DAG: Decl[Struct]/CurrModule:            MyPropertyWrapper[#Property Wrapper#]; name=MyPropertyWrapper
diff --git a/test/IRGen/extern_c.swift b/test/IRGen/extern_c.swift
@@ -15,10 +15,10 @@ func test() {
 test()
 
 // CHECK: declare void @explicit_extern_c()
-@extern(c, "explicit_extern_c") func explicit_extern_c()
+@_extern(c, "explicit_extern_c") func explicit_extern_c()
 
 // CHECK: declare void @implicit_extern_c()
-@extern(c) func implicit_extern_c()
+@_extern(c) func implicit_extern_c()
 
 // CHECK: declare void @default_arg_value(i32)
-@extern(c) func default_arg_value(_: Int32 = 42)
+@_extern(c) func default_arg_value(_: Int32 = 42)
diff --git a/test/IRGen/extern_c_abitypes.swift b/test/IRGen/extern_c_abitypes.swift
@@ -34,25 +34,25 @@ module c_abi_types {
 
 import c_abi_types
 
-@extern(c, "swift_roundtrip_void")
+@_extern(c, "swift_roundtrip_void")
 func swift_roundtrip_void()
-@extern(c, "swift_roundtrip_bool")
+@_extern(c, "swift_roundtrip_bool")
 func swift_roundtrip_bool(_: Bool) -> Bool
-@extern(c, "swift_roundtrip_char")
+@_extern(c, "swift_roundtrip_char")
 func swift_roundtrip_char(_: CChar) -> CChar
-@extern(c, "swift_roundtrip_int")
+@_extern(c, "swift_roundtrip_int")
 func swift_roundtrip_int(_: CInt) -> CInt
-@extern(c, "swift_roundtrip_float")
+@_extern(c, "swift_roundtrip_float")
 func swift_roundtrip_float(_: CFloat) -> CFloat
-@extern(c, "swift_roundtrip_double")
+@_extern(c, "swift_roundtrip_double")
 func swift_roundtrip_double(_: CDouble) -> CDouble
-@extern(c, "swift_roundtrip_opaque_ptr")
+@_extern(c, "swift_roundtrip_opaque_ptr")
 func swift_roundtrip_opaque_ptr(_: OpaquePointer!) -> OpaquePointer!
-@extern(c, "swift_roundtrip_void_star")
+@_extern(c, "swift_roundtrip_void_star")
 func swift_roundtrip_void_star(_: UnsafeMutableRawPointer!) -> UnsafeMutableRawPointer!
-@extern(c, "swift_roundtrip_c_struct")
+@_extern(c, "swift_roundtrip_c_struct")
 func swift_roundtrip_c_struct(_: c_struct) -> c_struct
-@extern(c, "swift_roundtrip_c_struct_ptr")
+@_extern(c, "swift_roundtrip_c_struct_ptr")
 func swift_roundtrip_c_struct_ptr(_: UnsafeMutablePointer<c_struct>!) -> UnsafeMutablePointer<c_struct>!
 
 func test() {
diff --git a/test/Interop/WebAssembly/extern-wasm-cdecls.swift b/test/Interop/WebAssembly/extern-wasm-cdecls.swift
@@ -2,23 +2,23 @@
 // RUN: %target-swift-frontend %s -emit-ir -enable-experimental-feature Extern -module-name Extern | %FileCheck %s
 
 // CHECK: declare void @import1() [[EA1:#[0-9]+]]
-@extern(c)
-@extern(wasm, module: "m0", name: "import1")
+@_extern(c)
+@_extern(wasm, module: "m0", name: "import1")
 func import1()
 
 // CHECK: declare i32 @import2WithReturnInt() [[EA2:#[0-9]+]]
-@extern(c)
-@extern(wasm, module: "m0", name: "import2")
+@_extern(c)
+@_extern(wasm, module: "m0", name: "import2")
 func import2WithReturnInt() -> Int32
 
 // CHECK: declare void @import3TakingInt(i32) [[EA3:#[0-9]+]]
-@extern(c)
-@extern(wasm, module: "m0", name: "import3")
+@_extern(c)
+@_extern(wasm, module: "m0", name: "import3")
 func import3TakingInt(_: Int32)
 
 // CHECK: declare void @c_import4() [[EA4:#[0-9]+]]
-@extern(c, "c_import4")
-@extern(wasm, module: "m0", name: "import4")
+@_extern(c, "c_import4")
+@_extern(wasm, module: "m0", name: "import4")
 func import4()
 
 func test() {
diff --git a/test/Interop/WebAssembly/extern-wasm-decls-to-swift.swift b/test/Interop/WebAssembly/extern-wasm-decls-to-swift.swift
@@ -2,15 +2,15 @@
 // RUN: %target-swift-frontend %s -enable-experimental-feature Extern -emit-ir -module-name Extern | %FileCheck %s
 
 // CHECK: declare {{.*}} void @"$s6Extern7import1yyF"() [[EA1:#[0-9]+]]
-@extern(wasm, module: "m0", name: "import1")
+@_extern(wasm, module: "m0", name: "import1")
 func import1()
 
 // CHECK: declare {{.*}} i32 @"$s6Extern20import2WithReturnInts5Int32VyF"() [[EA2:#[0-9]+]]
-@extern(wasm, module: "m0", name: "import2")
+@_extern(wasm, module: "m0", name: "import2")
 func import2WithReturnInt() -> Int32
 
 // CHECK: declare {{.*}} void @"$s6Extern16import3TakingIntyys5Int32VF"(i32) [[EA3:#[0-9]+]]
-@extern(wasm, module: "m0", name: "import3")
+@_extern(wasm, module: "m0", name: "import3")
 func import3TakingInt(_: Int32)
 
 func test() {
diff --git a/test/ModuleInterface/extern_attr.swift b/test/ModuleInterface/extern_attr.swift
@@ -5,16 +5,16 @@
 // RUN: %FileCheck %s < %t/Library.swiftinterface
 
 // CHECK:      #if compiler(>=5.3) && $Extern
-// CHECK-NEXT:   @extern(c) public func externalCFunc()
+// CHECK-NEXT:   @_extern(c) public func externalCFunc()
 // CHECK-NEXT: #endif
-@extern(c) public func externalCFunc()
+@_extern(c) public func externalCFunc()
 
 // CHECK:      #if compiler(>=5.3) && $Extern
-// CHECK-NEXT:   @extern(c, "renamedCFunc") public func externalRenamedCFunc()
+// CHECK-NEXT:   @_extern(c, "renamedCFunc") public func externalRenamedCFunc()
 // CHECK-NEXT: #endif
-@extern(c, "renamedCFunc") public func externalRenamedCFunc()
+@_extern(c, "renamedCFunc") public func externalRenamedCFunc()
 
 // CHECK:      #if compiler(>=5.3) && $Extern
-// CHECK-NEXT:   @extern(wasm, module: "m", name: "f") public func wasmImportedFunc()
+// CHECK-NEXT:   @_extern(wasm, module: "m", name: "f") public func wasmImportedFunc()
 // CHECK-NEXT: #endif
-@extern(wasm, module: "m", name: "f") public func wasmImportedFunc()
+@_extern(wasm, module: "m", name: "f") public func wasmImportedFunc()
diff --git a/test/SILGen/extern_c.swift b/test/SILGen/extern_c.swift
diff --git a/test/Serialization/attr-extern.swift b/test/Serialization/attr-extern.swift
diff --git a/test/attr/attr_extern.swift b/test/attr/attr_extern.swift
diff --git a/test/attr/attr_extern_fixit.swift b/test/attr/attr_extern_fixit.swift
diff --git a/test/attr/attr_extern_fixit.swift.result b/test/attr/attr_extern_fixit.swift.result
diff --git a/test/stdlib/Runtime.swift.gyb b/test/stdlib/Runtime.swift.gyb
