[swift] Stop using _SwiftDispatchOverlayShims

Stop importing _SwiftDispatchOverlayShims from the Swift stdlib; instead, copy its contents to a new private _DispatchOverlayShims module, and import it with the @_implementationOnly attribute so that clients no longer need to have access to it to merely import Dispatch.

The Swift stdlib currently ships the _SwiftDispatchOverlayShims module, but we don't want to keep it there -- it declares APIs that belong to the dispatch project, and it is best maintained by the same people who maintain the library itself.

The Dispatch overlay on Darwin has not been importing this module for a couple years now.

Author: lorentey

src/swift/Block.swift

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import CDispatch
-import _SwiftDispatchOverlayShims
+@_implementationOnly import _DispatchOverlayShims
 
 public struct DispatchWorkItemFlags : OptionSet, RawRepresentable {
 	public let rawValue: UInt

src/swift/CMakeLists.txt

@@ -31,7 +31,8 @@ add_library(swiftDispatch
 target_compile_options(swiftDispatch PRIVATE
   "SHELL:-Xcc -fblocks"
   "SHELL:-Xcc -fmodule-map-file=${PROJECT_SOURCE_DIR}/dispatch/module.modulemap"
-  "SHELL:-Xcc -I${PROJECT_SOURCE_DIR}")
+  "SHELL:-Xcc -I${PROJECT_SOURCE_DIR}"
+  "SHELL:-Xcc -I${PROJECT_SOURCE_DIR}/src/swift/shims")
 set_target_properties(swiftDispatch PROPERTIES
   Swift_MODULE_NAME Dispatch
   Swift_MODULE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/swift

src/swift/Data.swift

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import CDispatch
-import _SwiftDispatchOverlayShims
+@_implementationOnly import _DispatchOverlayShims
 
 public struct DispatchData : RandomAccessCollection {
 	public typealias Iterator = DispatchDataIterator

src/swift/Queue.swift

@@ -13,7 +13,7 @@
 // dispatch/queue.h
 
 import CDispatch
-import _SwiftDispatchOverlayShims
+@_implementationOnly import _DispatchOverlayShims
 
 public final class DispatchSpecificKey<T> {
 	public init() {}

src/swift/Source.swift

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import CDispatch
-import _SwiftDispatchOverlayShims
+@_implementationOnly import _DispatchOverlayShims
 #if os(Windows)
 import WinSDK
 #endif

src/swift/Wrapper.swift

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import CDispatch
-import _SwiftDispatchOverlayShims
+@_implementationOnly import _DispatchOverlayShims
 
 // This file contains declarations that are provided by the
 // importer via Dispatch.apinote when the platform has Objective-C support

src/swift/shims/DispatchOverlayShims.h

@@ -0,0 +1,253 @@
+//===--- DispatchOverlayShims.h - Compatibility decls -----------*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+
+#ifndef SWIFT_SHIMS_DISPATCH_OVERLAY_SHIMS_H
+#define SWIFT_SHIMS_DISPATCH_OVERLAY_SHIMS_H
+
+#include <dispatch/dispatch.h>
+
+#ifdef __OBJC__
+#define SWIFT_DISPATCH_RETURNS_RETAINED __attribute__((__ns_returns_retained__))
+#else
+#define SWIFT_DISPATCH_RETURNS_RETAINED
+#endif
+
+#define SWIFT_DISPATCH_NOESCAPE __attribute__((__noescape__))
+
+#pragma clang assume_nonnull begin
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef void (^__swift_shims_dispatch_block_t)(void);
+
+#ifdef __OBJC__
+typedef id __swift_shims_dispatch_data_t;
+#else
+typedef void *__swift_shims_dispatch_data_t;
+#endif
+
+
+static inline dispatch_queue_attr_t
+_swift_dispatch_queue_concurrent(void) {
+  return DISPATCH_QUEUE_CONCURRENT;
+}
+
+static inline dispatch_queue_t
+_swift_dispatch_get_main_queue(void) {
+  return dispatch_get_main_queue();
+}
+
+static inline dispatch_data_t
+_swift_dispatch_data_empty(void) {
+  return dispatch_data_empty;
+}
+
+static inline __swift_shims_dispatch_block_t _Nullable
+_swift_dispatch_data_destructor_default(void) {
+  return DISPATCH_DATA_DESTRUCTOR_DEFAULT;
+}
+
+static inline __swift_shims_dispatch_block_t
+_swift_dispatch_data_destructor_free(void) {
+  return _dispatch_data_destructor_free;
+}
+
+static inline __swift_shims_dispatch_block_t
+_swift_dispatch_data_destructor_munmap(void) {
+  return _dispatch_data_destructor_munmap;
+}
+
+#define SWIFT_DISPATCH_SOURCE_TYPE(t)                                          \
+  static inline dispatch_source_type_t _swift_dispatch_source_type_##t(void) { \
+    return DISPATCH_SOURCE_TYPE_##t;                                           \
+  }
+
+SWIFT_DISPATCH_SOURCE_TYPE(DATA_ADD)
+SWIFT_DISPATCH_SOURCE_TYPE(DATA_OR)
+SWIFT_DISPATCH_SOURCE_TYPE(DATA_REPLACE)
+SWIFT_DISPATCH_SOURCE_TYPE(READ)
+SWIFT_DISPATCH_SOURCE_TYPE(SIGNAL)
+SWIFT_DISPATCH_SOURCE_TYPE(TIMER)
+SWIFT_DISPATCH_SOURCE_TYPE(WRITE)
+
+#if __APPLE__
+SWIFT_DISPATCH_SOURCE_TYPE(MACH_SEND)
+SWIFT_DISPATCH_SOURCE_TYPE(MACH_RECV)
+SWIFT_DISPATCH_SOURCE_TYPE(MEMORYPRESSURE)
+SWIFT_DISPATCH_SOURCE_TYPE(PROC)
+SWIFT_DISPATCH_SOURCE_TYPE(VNODE)
+#endif
+
+extern void
+_swift_dispatch_source_create_abort(void);
+
+SWIFT_DISPATCH_RETURNS_RETAINED
+static inline dispatch_source_t
+_swift_dispatch_source_create(
+    dispatch_source_type_t type,
+	uintptr_t handle,
+	unsigned long mask,
+	dispatch_queue_t _Nullable queue)
+{
+  dispatch_source_t source = dispatch_source_create(type, handle, mask, queue);
+  if (!source) {
+    _swift_dispatch_source_create_abort();
+  }
+  return source;
+}
+
+static inline SWIFT_DISPATCH_RETURNS_RETAINED __swift_shims_dispatch_block_t
+_swift_dispatch_block_create_with_qos_class(
+    dispatch_block_flags_t flags, dispatch_qos_class_t qos,
+    int relative_priority, __swift_shims_dispatch_block_t _Nonnull block) {
+  return dispatch_block_create_with_qos_class(
+      flags, qos, relative_priority, block);
+}
+
+static inline __swift_shims_dispatch_block_t
+_swift_dispatch_block_create_noescape(
+    dispatch_block_flags_t flags,
+    __swift_shims_dispatch_block_t SWIFT_DISPATCH_NOESCAPE block) {
+  return dispatch_block_create(flags, block);
+}
+
+static inline int _swift_dispatch_block_wait(
+    __swift_shims_dispatch_block_t block,
+    unsigned long long timeout) {
+  return dispatch_block_wait(block, timeout);
+}
+
+static inline void _swift_dispatch_block_notify(
+    __swift_shims_dispatch_block_t block,
+    dispatch_queue_t queue,
+    __swift_shims_dispatch_block_t notifier) {
+  dispatch_block_notify(block, queue, notifier);
+}
+
+static inline void _swift_dispatch_block_cancel(
+    __swift_shims_dispatch_block_t block) {
+  dispatch_block_cancel(block);
+}
+
+static inline int _swift_dispatch_block_testcancel(
+    __swift_shims_dispatch_block_t block) {
+  return dispatch_block_testcancel(block);
+}
+
+static inline void _swift_dispatch_async(
+    dispatch_queue_t queue,
+    __swift_shims_dispatch_block_t block) {
+  dispatch_async(queue, block);
+}
+
+static inline void _swift_dispatch_sync(
+    dispatch_queue_t queue,
+    __swift_shims_dispatch_block_t block) {
+  dispatch_sync(queue, block);
+}
+
+static inline void _swift_dispatch_barrier_async(
+    dispatch_queue_t queue,
+    __swift_shims_dispatch_block_t block) {
+  dispatch_barrier_async(queue, block);
+}
+
+static inline void _swift_dispatch_group_async(
+    dispatch_group_t group,
+    dispatch_queue_t queue,
+    __swift_shims_dispatch_block_t block) {
+  dispatch_group_async((dispatch_group_t)group, queue, block);
+}
+
+static inline void _swift_dispatch_group_notify(
+    dispatch_group_t group,
+    dispatch_queue_t queue,
+    __swift_shims_dispatch_block_t block) {
+  dispatch_group_notify(group, queue, block);
+}
+
+static inline void _swift_dispatch_after(
+    dispatch_time_t when,
+    dispatch_queue_t queue,
+    __swift_shims_dispatch_block_t block) {
+  dispatch_after(when, queue, block);
+}
+
+
+static inline void _swift_dispatch_apply_current(
+    size_t iterations,
+    void SWIFT_DISPATCH_NOESCAPE (^block)(intptr_t)) {
+  dispatch_apply(iterations, (dispatch_queue_t _Nonnull)0, ^(size_t i){
+    block((intptr_t)i);
+  });
+}
+
+SWIFT_DISPATCH_RETURNS_RETAINED
+static inline __swift_shims_dispatch_data_t
+_swift_dispatch_data_create(
+    const void *buffer,
+    size_t size,
+    dispatch_queue_t _Nullable queue,
+    __swift_shims_dispatch_block_t _Nullable destructor) {
+  return dispatch_data_create(buffer, size, queue, destructor);
+}
+
+typedef unsigned int (^__swift_shims_dispatch_data_applier)(__swift_shims_dispatch_data_t, size_t, const void *, size_t);
+
+static inline unsigned int
+_swift_dispatch_data_apply(
+    __swift_shims_dispatch_data_t data,
+    __swift_shims_dispatch_data_applier SWIFT_DISPATCH_NOESCAPE applier) {
+  return dispatch_data_apply((dispatch_data_t)data, ^bool(dispatch_data_t data, size_t off, const void *loc, size_t size){
+    return applier((__swift_shims_dispatch_data_t)data, off, loc, size);
+  });
+}
+
+static inline void _swift_dispatch_source_set_event_handler(
+    dispatch_source_t source,
+    __swift_shims_dispatch_block_t _Nullable block) {
+  dispatch_source_set_event_handler(source, block);
+}
+
+static inline void _swift_dispatch_source_set_cancel_handler(
+    dispatch_source_t source,
+    __swift_shims_dispatch_block_t _Nullable block) {
+  dispatch_source_set_cancel_handler(source, block);
+}
+
+static inline void _swift_dispatch_source_set_registration_handler(
+    dispatch_source_t source,
+    __swift_shims_dispatch_block_t _Nullable block) {
+  dispatch_source_set_registration_handler(source, block);
+}
+
+#if defined(__ANDROID__)
+extern void _dispatch_install_thread_detach_callback(void (*cb)(void));
+#endif
+
+static inline void _swift_dispatch_retain(dispatch_object_t object) {
+  dispatch_retain(object);
+}
+
+static inline void _swift_dispatch_release(dispatch_object_t object) {
+  dispatch_release(object);
+}
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#pragma clang assume_nonnull end
+
+#endif // SWIFT_SHIMS_DISPATCH_OVERLAY_SHIMS_H
+

src/swift/shims/module.modulemap

@@ -0,0 +1,3 @@
+module _DispatchOverlayShims {
+  header "DispatchOverlayShims.h"
+}