[CMake] Simplify writing of modulemap.

Instead of a two-step process that writes the dynamic contents at
CMake configure time, and a build-time step that concatenates the static
and dynamic part of the modulemap, CMake's configure_file is used to
directly write the full contents at configure time.

Author: hageboeck

CMakeLists.txt

@@ -421,36 +421,14 @@ get_property(__allBuiltins GLOBAL PROPERTY ROOT_BUILTIN_TARGETS)
 add_custom_target(move_headers ALL DEPENDS ${__allHeaders} ${__allBuiltins} gitinfotxt)
 
 #---CXX MODULES-----------------------------------------------------------------------------------
-if(MSVC)
-  set(_os_cat "type")
-else()
-  set(_os_cat "cat")
-endif()
-cmake_path(CONVERT "${CMAKE_BINARY_DIR}/include/module.modulemap.extra" TO_NATIVE_PATH_LIST _from_native)
-cmake_path(CONVERT "${CMAKE_BINARY_DIR}/include/ROOT.modulemap" TO_NATIVE_PATH_LIST _to_native)
-
-add_custom_target(copymodulemap DEPENDS "${CMAKE_BINARY_DIR}/include/ROOT.modulemap")
-add_custom_command(
-		  OUTPUT "${CMAKE_BINARY_DIR}/include/ROOT.modulemap"
-                  DEPENDS cmake/unix/module.modulemap "${CMAKE_BINARY_DIR}/include/module.modulemap.extra"
-		  COMMAND ${CMAKE_COMMAND} -E copy "${CMAKE_SOURCE_DIR}/cmake/unix/module.modulemap" "${CMAKE_BINARY_DIR}/include/ROOT.modulemap"
-                  COMMAND ${_os_cat} "${_from_native}" >> "${_to_native}"
-)
-install(FILES "${CMAKE_BINARY_DIR}/include/ROOT.modulemap" DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} COMPONENT headers)
-
-add_dependencies(move_headers copymodulemap)
-
 # Take all the modulemap contents we collected from the packages and append them to our modulemap.
 # We have to delay this because the ROOT_CXXMODULES_EXTRA_MODULEMAP_CONTENT is filled in the
 # add_subdirectory calls above.
 get_property(__modulemap_extra_content GLOBAL PROPERTY ROOT_CXXMODULES_EXTRA_MODULEMAP_CONTENT)
-string(REPLACE ";" "" __modulemap_extra_content "${__modulemap_extra_content}")
-# Write module.modulemap.extra to a temporary file first, to not touch module.modulemap.extra
-# if it's unchanged.
-file(WRITE "${CMAKE_BINARY_DIR}/include/module.modulemap.extra.tmp" "${__modulemap_extra_content}")
-configure_file("${CMAKE_BINARY_DIR}/include/module.modulemap.extra.tmp"
-    "${CMAKE_BINARY_DIR}/include/module.modulemap.extra"
-    COPYONLY)
+string(REPLACE ";" "" ROOT_GENERATED_MODULEMAP_CONTENT "${__modulemap_extra_content}")
+# Now append the generated content to the original modulemap
+configure_file(${CMAKE_SOURCE_DIR}/cmake/unix/module.modulemap ${CMAKE_BINARY_DIR}/include/ROOT.modulemap)
+install(FILES "${CMAKE_BINARY_DIR}/include/ROOT.modulemap" DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} COMPONENT headers)
 
 # From now on we handled all exposed module and want to make all new modulemaps private to ROOT.
 set(ROOT_CXXMODULES_WRITE_TO_CURRENT_DIR ON)

cmake/unix/module.modulemap

@@ -70,3 +70,4 @@ module "Graf3D.X3DBuffer.h_C" {
 }
 
 // From this point on the contents of this file are automatically generated.
+@ROOT_GENERATED_MODULEMAP_CONTENT@