build: slightly improve the build for libdispatch

Avoid polluting the build directory a small amount given that we can use
`-fmodule-map-file=` for the C/C++ build of libdispatch.  Unfortunately,
for the Swift build, we need to have the file copied over due to the
umbrella header resolution.

Hopefully this reduces some of the race conditions that we have seen in
the build.

Thanks to @dgregor for reminding me of the flag!

Author: compnerd

.gitignore

@@ -30,4 +30,3 @@ configure
 libtool
 .dirstamp
 /dispatch/module.modulemap
-/private/module.modulemap

CMakeLists.txt

@@ -261,26 +261,12 @@ endif()
 
 
 if(CMAKE_SYSTEM_NAME STREQUAL Darwin)
-  add_custom_command(OUTPUT
-                       "${PROJECT_SOURCE_DIR}/dispatch/module.modulemap"
-                       "${PROJECT_SOURCE_DIR}/private/module.modulemap"
-                     COMMAND
-                       ${CMAKE_COMMAND} -E copy_if_different "${PROJECT_SOURCE_DIR}/dispatch/darwin/module.modulemap" "${PROJECT_SOURCE_DIR}/dispatch/module.modulemap"
-                     COMMAND
-                       ${CMAKE_COMMAND} -E copy_if_different "${PROJECT_SOURCE_DIR}/private/darwin/module.modulemap" "${PROJECT_SOURCE_DIR}/private/module.modulemap")
+  add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-fmodule-map-file=${PROJECT_SOURCE_DIR}/dispatch/darwin/module.modulemap>
+                      $<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-fmodule-map-file=${PROJECT_SOURCE_DIR}/private/darwin/module.modulemap>)
 else()
-  add_custom_command(OUTPUT
-                       "${PROJECT_SOURCE_DIR}/dispatch/module.modulemap"
-                       "${PROJECT_SOURCE_DIR}/private/module.modulemap"
-                     COMMAND
-                       ${CMAKE_COMMAND} -E copy_if_different "${PROJECT_SOURCE_DIR}/dispatch/generic/module.modulemap" "${PROJECT_SOURCE_DIR}/dispatch/module.modulemap"
-                     COMMAND
-                       ${CMAKE_COMMAND} -E copy_if_different "${PROJECT_SOURCE_DIR}/private/generic/module.modulemap" "${PROJECT_SOURCE_DIR}/private/module.modulemap")
+  add_compile_options($<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-fmodule-map-file=${PROJECT_SOURCE_DIR}/dispatch/generic/module.modulemap>
+                      $<$<OR:$<COMPILE_LANGUAGE:C>,$<COMPILE_LANGUAGE:CXX>>:-fmodule-map-file=${PROJECT_SOURCE_DIR}/private/generic/module.modulemap>)
 endif()
-add_custom_target(module-maps ALL
-                  DEPENDS
-                     "${PROJECT_SOURCE_DIR}/dispatch/module.modulemap"
-                     "${PROJECT_SOURCE_DIR}/private/module.modulemap")
 
 configure_file("${PROJECT_SOURCE_DIR}/cmake/config.h.in"
                "${PROJECT_BINARY_DIR}/config/config_ac.h")

src/swift/CMakeLists.txt

@@ -18,6 +18,18 @@ target_include_directories(DispatchStubs PRIVATE
 set_target_properties(DispatchStubs PROPERTIES
   POSITION_INDEPENDENT_CODE YES)
 
+
+if(CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  add_custom_command(OUTPUT ${PROJECT_SOURCE_DIR}/dispatch/module.modulemap
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${PROJECT_SOURCE_DIR}/dispatch/darwin/module.modulemap ${PROJECT_SOURCE_DIR}/dispatch/module.modulemap)
+else()
+  add_custom_command(OUTPUT ${PROJECT_SOURCE_DIR}/dispatch/module.modulemap
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${PROJECT_SOURCE_DIR}/dispatch/generic/module.modulemap ${PROJECT_SOURCE_DIR}/dispatch/module.modulemap)
+endif()
+add_custom_target(module-map ALL
+  DEPENDS ${PROJECT_SOURCE_DIR}/dispatch/module.modulemap)
+
+
 add_library(swiftDispatch
   Block.swift
   Data.swift
@@ -42,7 +54,7 @@ target_link_libraries(swiftDispatch PRIVATE
   BlocksRuntime::BlocksRuntime)
 target_link_libraries(swiftDispatch PUBLIC
   dispatch)
-add_dependencies(swiftDispatch module-maps)
+add_dependencies(swiftDispatch module-map)
 
 get_swift_host_arch(swift_arch)
 install(FILES