Meta: Add a script and CMake function to generate a clang module map

In theory the clang module map should not have absolute paths for the
headers. Other Swift projects seem to use the -ivfsoverlay feature of
clang to work around this, but it seems difficult to get to work.

.github/actions/setup/action.yml

@@ -53,7 +53,7 @@ runs:
         set -e
         sudo xcode-select --switch /Applications/Xcode_16.0.app
         brew update
-        brew install autoconf autoconf-archive automake bash ccache coreutils ffmpeg llvm@18 nasm ninja qt unzip wabt
+        brew install autoconf autoconf-archive automake bash ccache coreutils ffmpeg llvm@18 nasm ninja qt unzip wabt pyyaml
 
     - name: 'Install vcpkg'
       shell: bash

Meta/CMake/Swift/GenerateSwiftHeader.cmake

@@ -23,7 +23,7 @@ function(_swift_generate_cxx_header target header)
     return()
   endif()
 
-  cmake_parse_arguments(PARSE_ARGV 2 "ARG" "" "MODULE_NAME;CXX_STD_VERSION" "SEARCH_PATHS")
+  cmake_parse_arguments(PARSE_ARGV 2 "ARG" "" "MODULE_NAME;CXX_STD_VERSION" "SEARCH_PATHS;COMPILE_OPTIONS")
 
   if(NOT ARG_MODULE_NAME)
     set(target_module_name $<TARGET_PROPERTY:${target},Swift_MODULE_NAME>)
@@ -70,6 +70,7 @@ function(_swift_generate_cxx_header target header)
       ${_SwiftSources}
       ${SDK_FLAGS}
       ${CXX_STD_FLAGS}
+      ${ARG_COMPILE_OPTIONS}
       -Xcc -Wno-unqualified-std-cast-call
       -Xcc -Wno-user-defined-literals
       -Xcc -Wno-unknown-warning-option

Meta/CMake/code_generators.cmake

@@ -23,6 +23,31 @@ function(embed_as_string_view name source_file output source_variable_name)
     add_dependencies(all_generated "generate_${name}")
 endfunction()
 
+function(generate_clang_module_map target_name)
+    cmake_parse_arguments(PARSE_ARGV 1 MODULE_MAP "" "DIRECTORY" "GENERATED_FILES")
+    if (NOT MODULE_MAP_DIRECTORY)
+        set(MODULE_MAP_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}")
+    endif()
+
+    set(module_map_file "${CMAKE_CURRENT_BINARY_DIR}/module/module.modulemap")
+    set(vfs_overlay_file "${CMAKE_CURRENT_BINARY_DIR}/vfs_overlay.yaml")
+
+    find_package(Python3 REQUIRED COMPONENTS Interpreter)
+    # FIXME: Make this depend on the public headers of the target
+    add_custom_command(
+        OUTPUT "${module_map_file}"
+        COMMAND "${Python3_EXECUTABLE}" "${SerenityOS_SOURCE_DIR}/Meta/generate_clang_module_map.py" "${MODULE_MAP_DIRECTORY}" --module-map "${module_map_file}" --vfs-map ${vfs_overlay_file} ${MODULE_MAP_GENERATED_FILES}
+        VERBATIM
+        DEPENDS "${SerenityOS_SOURCE_DIR}/Meta/generate_clang_module_map.py"
+    )
+
+    add_custom_target("generate_${target_name}_module_map" DEPENDS "${module_map_file}")
+    add_dependencies(all_generated "generate_${target_name}_module_map")
+    add_dependencies("${target_name}" "generate_${target_name}_module_map")
+
+    target_compile_options(${target_name} PUBLIC "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-Xcc -ivfsoverlay${vfs_overlay_file}>")
+endfunction()
+
 function(compile_ipc source output)
     if (NOT IS_ABSOLUTE ${source})
         set(source ${CMAKE_CURRENT_SOURCE_DIR}/${source})

Meta/generate_clang_module_map.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""
+    Generates a clang module map for a given directory
+"""
+
+import argparse
+import pathlib
+import yaml
+import sys
+
+
+def write_file_if_not_same(file_path, content):
+    try:
+        with open(file_path, 'r') as f:
+            if f.read() == content:
+                return
+    except FileNotFoundError:
+        pass
+
+    with open(file_path, 'w') as f:
+        f.write(content)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+                 epilog=__doc__,
+                 formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument('directory', help='source directory to generate module map for')
+    parser.add_argument('generated_files', nargs='+', help='extra files to include in the module map')
+    parser.add_argument('-m', '--module-map', required=True, help='output module map file')
+    parser.add_argument('-v', '--vfs-map', required=True, help='output VFS map file')
+    args = parser.parse_args()
+
+    root = pathlib.Path(args.directory)
+    if not root.is_dir():
+        print(f"Error: {args.directory} is not a directory", file=sys.stderr)
+        return 1
+    pathlib.Path(args.module_map).parent.mkdir(parents=True, exist_ok=True)
+
+    header_files = [f for f in root.rglob('**/*.h') if f.is_file()]
+    module_name = root.name
+
+    module_map = f"module {module_name} {{\n"
+    for header_file in header_files:
+        module_map += f"    header \"{header_file.relative_to(root)}\"\n"
+    for generated_file in args.generated_files:
+        module_map += f"    header \"{generated_file}\"\n"
+    module_map += "    requires cplusplus\n"
+    module_map += "    export *\n"
+    module_map += "}\n"
+
+    vfs_map = {
+        "version": 0,
+        "use-external-names": False,
+        "roots": [
+            {
+                "name": f"{root}/module.modulemap",
+                "type": "file",
+                "external-contents": f"{args.module_map}"
+            }
+        ]
+    }
+
+    write_file_if_not_same(args.module_map, module_map)
+    write_file_if_not_same(args.vfs_map, yaml.dump(vfs_map))
+
+
+if __name__ == '__main__':
+    sys.exit(main())