swiftlang · seabaylea · Jan 13, 2016
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -37,9 +37,13 @@ option(SWIFT_BUILD_STDLIB
     TRUE)
 
 option(SWIFT_BUILD_SDK_OVERLAY
-    "Build Swift SDK overlay"
+    "Build Swift SDK overlay (Darwin only)"
     TRUE)
 
+option(SWIFT_BUILD_DISPATCH_OVERLAY
+    "Build Swift Grand Central Dispatch overlay (on Linux; on Darwin, controlled by SWIFT_BUILD_SDK_OVERLAY)"
+    FALSE)
+
 option(SWIFT_BUILD_STATIC_STDLIB
     "Build static variants of the Swift standard library and SDK overlay"
     FALSE)
@@ -590,11 +594,19 @@ message(STATUS "  Build type: ${CMAKE_BUILD_TYPE}")
 message(STATUS "  Assertions: ${LLVM_ENABLE_ASSERTIONS}")
 message(STATUS "")
 
-message(STATUS "Building Swift standard library and SDK overlays for SDKs: ${SWIFT_SDKS}")
+message(STATUS "Building Swift standard library for SDKs: ${SWIFT_SDKS}")
 message(STATUS "  Build type: ${SWIFT_STDLIB_BUILD_TYPE}")
 message(STATUS "  Assertions: ${SWIFT_STDLIB_ASSERTIONS}")
 message(STATUS "")
 
+message(STATUS "Building Swift overlays for SDKs: ${SWIFT_SDKS}")
+if("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "LINUX")
+  message(STATUS "  libdispatch overlay: ${SWIFT_BUILD_DISPATCH_OVERLAY}")
+else()
+  message(STATUS "  SDK overlays: ${SWIFT_BUILD_SDK_OVERLAY}")
+endif()
+message(STATUS "")
+
 message(STATUS "Building Swift runtime with:")
 message(STATUS "  Dtrace:                             ${SWIFT_RUNTIME_ENABLE_DTRACE}")
 message(STATUS "  Leak Detection Checker Entrypoints: ${SWIFT_RUNTIME_ENABLE_LEAK_CHECKER}")
@@ -618,18 +630,19 @@ endif()
 #
 # Set up global CMake variables for API notes.
 #
+if("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin")
+  set(SWIFT_API_NOTES_PATH "${SWIFT_SOURCE_DIR}/apinotes")
+  if(NOT EXISTS "${SWIFT_API_NOTES_PATH}/Foundation.apinotes")
+    message(FATAL_ERROR "API notes are not available in ${SWIFT_API_NOTES_PATH}")
+  endif()
 
-set(SWIFT_API_NOTES_PATH "${SWIFT_SOURCE_DIR}/apinotes")
-if(NOT EXISTS "${SWIFT_API_NOTES_PATH}/Foundation.apinotes")
-  message(FATAL_ERROR "API notes are not available in ${SWIFT_API_NOTES_PATH}")
+  file(GLOB SWIFT_API_NOTES_INPUT_FILES "${SWIFT_API_NOTES_PATH}/*.apinotes")
+  foreach(file ${SWIFT_API_NOTES_INPUT_FILES})
+    get_filename_component(name "${file}" NAME_WE)
+    list(APPEND SWIFT_API_NOTES_INPUTS ${name})
+  endforeach()
 endif()
 
-file(GLOB SWIFT_API_NOTES_INPUT_FILES "${SWIFT_API_NOTES_PATH}/*.apinotes")
-foreach(file ${SWIFT_API_NOTES_INPUT_FILES})
-  get_filename_component(name "${file}" NAME_WE)
-  list(APPEND SWIFT_API_NOTES_INPUTS ${name})
-endforeach()
-
 # Add all of the subdirectories, where we actually do work.
 if(SWIFT_BUILD_TOOLS)
   add_subdirectory(include)

diff --git a/stdlib/public/CMakeLists.txt b/stdlib/public/CMakeLists.txt
@@ -24,9 +24,13 @@ endif()
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   if(SWIFT_BUILD_SDK_OVERLAY)
     add_subdirectory(SDK)
+    add_subdirectory(Dispatch)
   endif()
 endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
   add_subdirectory(Glibc)
+  if(SWIFT_BUILD_DISPATCH_OVERLAY)
+    add_subdirectory(Dispatch)
+  endif()
 endif()
diff --git a/stdlib/public/Dispatch/CMakeLists.txt b/stdlib/public/Dispatch/CMakeLists.txt
@@ -0,0 +1,14 @@
+if("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "LINUX")
+  add_swift_library(swiftDispatch IS_SDK_OVERLAY
+    Dispatch.cpp
+    Dispatch.swift
+
+    LINK_FLAGS "-ldispatch")
+else()
+  add_swift_library(swiftDispatch IS_SDK_OVERLAY
+    Dispatch.cpp
+    Dispatch.swift
+
+    SWIFT_MODULE_DEPENDS ObjectiveC)
+endif()
+
diff --git a/stdlib/public/SDK/Dispatch/Dispatch.mm → stdlib/public/Dispatch/Dispatch.cpp b/stdlib/public/SDK/Dispatch/Dispatch.mm → stdlib/public/Dispatch/Dispatch.cpp
@@ -33,12 +33,15 @@
 
 SOURCE(DATA_ADD)
 SOURCE(DATA_OR)
-SOURCE(MACH_SEND)
-SOURCE(MACH_RECV)
-SOURCE(MEMORYPRESSURE)
 SOURCE(PROC)
 SOURCE(READ)
 SOURCE(SIGNAL)
 SOURCE(TIMER)
 SOURCE(VNODE)
 SOURCE(WRITE)
+
+#if defined (__APPLE__)
+SOURCE(MACH_SEND)
+SOURCE(MACH_RECV)
+SOURCE(MEMORYPRESSURE)
+#endif
diff --git a/stdlib/public/SDK/Dispatch/Dispatch.swift → stdlib/public/Dispatch/Dispatch.swift b/stdlib/public/SDK/Dispatch/Dispatch.swift → stdlib/public/Dispatch/Dispatch.swift
@@ -64,11 +64,19 @@ public var DISPATCH_QUEUE_PRIORITY_BACKGROUND: dispatch_queue_priority_t {
   return -32768
 }
 
+#if _runtime(_ObjC)
 @warn_unused_result
 public func dispatch_get_global_queue(identifier: qos_class_t,
                                       _ flags: UInt) -> dispatch_queue_t {
   return dispatch_get_global_queue(Int(identifier.rawValue), flags)
 }
+#else
+@warn_unused_result
+public func dispatch_get_global_queue(identifier: CInt,
+                                      _ flags: UInt) -> dispatch_queue_t {
+  return dispatch_get_global_queue(identifier, flags)
+}
+#endif
 
 public var DISPATCH_QUEUE_CONCURRENT: dispatch_queue_attr_t {
   return _swift_dispatch_queue_concurrent()
@@ -122,6 +130,8 @@ public var DISPATCH_SOURCE_TYPE_DATA_ADD: dispatch_source_type_t {
 public var DISPATCH_SOURCE_TYPE_DATA_OR: dispatch_source_type_t {
   return _swift_dispatch_source_type_data_or()
 }
+
+#if _runtime(_ObjC)
 public var DISPATCH_SOURCE_TYPE_MACH_SEND: dispatch_source_type_t {
   return _swift_dispatch_source_type_mach_send()
 }
@@ -131,6 +141,8 @@ public var DISPATCH_SOURCE_TYPE_MACH_RECV: dispatch_source_type_t {
 public var DISPATCH_SOURCE_TYPE_MEMORYPRESSURE: dispatch_source_type_t {
   return _swift_dispatch_source_type_memorypressure()
 }
+#endif
+
 public var DISPATCH_SOURCE_TYPE_READ: dispatch_source_type_t {
   return _swift_dispatch_source_type_read()
 }

diff --git a/stdlib/public/SDK/CMakeLists.txt b/stdlib/public/SDK/CMakeLists.txt
@@ -14,7 +14,6 @@ add_subdirectory(CoreImage)
 add_subdirectory(CoreLocation)
 add_subdirectory(CoreMedia)
 add_subdirectory(Darwin)
-add_subdirectory(Dispatch)
 add_subdirectory(EventKit)
 add_subdirectory(Foundation)
 add_subdirectory(GameKit)

diff --git a/stdlib/public/SDK/Dispatch/CMakeLists.txt b/stdlib/public/SDK/Dispatch/CMakeLists.txt
diff --git a/utils/build-script-impl b/utils/build-script-impl
@@ -141,6 +141,7 @@ KNOWN_SETTINGS=(
     build-swift-tools           "1"              "set to 1 to build Swift host tools"
     build-swift-stdlib          "1"              "set to 1 to build the Swift standard library"
     build-swift-sdk-overlay     "1"              "set to 1 to build the Swift SDK overlay"
+    build-swift-dispatch-overlay "0"             "set to 1 to build the Swift libdispatch overlay on Linux"
     build-swift-static-stdlib   "0"              "set to 1 to build static versions of the Swift standard library and SDK overlay"
     build-swift-examples        "1"              "set to 1 to build examples"
     build-swift-perf-testsuite  "0"              "set to 1 to build perf test suite"
@@ -1600,6 +1601,7 @@ for deployment_target in "${NATIVE_TOOLS_DEPLOYMENT_TARGETS[@]}" "${CROSS_TOOLS_
                     -DSWIFT_BUILD_TOOLS:BOOL=$(true_false "${BUILD_SWIFT_TOOLS}")
                     -DSWIFT_BUILD_STDLIB:BOOL=$(true_false "${BUILD_SWIFT_STDLIB}")
                     -DSWIFT_BUILD_SDK_OVERLAY:BOOL=$(true_false "${BUILD_SWIFT_SDK_OVERLAY}")
+                    -DSWIFT_BUILD_DISPATCH_OVERLAY:BOOL=$(true_false "${BUILD_SWIFT_DISPATCH_OVERLAY}")
                     -DSWIFT_BUILD_STATIC_STDLIB:BOOL=$(true_false "${BUILD_SWIFT_STATIC_STDLIB}")
                     -DSWIFT_BUILD_PERF_TESTSUITE:BOOL=$(true_false "${build_perf_testsuite_this_time}")
                     -DSWIFT_BUILD_EXAMPLES:BOOL=$(true_false "${BUILD_SWIFT_EXAMPLES}")