Tools/Scripts/rewrite-compile-commands

#!/usr/bin/env python3

# Copyright (C) 2023 Igalia S.L.
#
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import argparse
import hashlib
import json
import os
import re
import sys

parser = argparse.ArgumentParser(
    description='This tool takes the compile_commands.json output by CMake and expands any UnifiedSources in it to regular sources.'
)
parser.add_argument('input_file')
parser.add_argument('output_file')
parser.add_argument('source_dir')
parser.add_argument('build_dir')

args = parser.parse_args()
source_dir = args.source_dir
build_dir = args.build_dir

# CMake regenerates the input on every reconfigure with a fresh mtime even when
# content is identical, so ninja keeps invoking us. Short-circuit on input hash.
with open(args.input_file, 'rb') as f:
    input_data = f.read()
input_hash = hashlib.sha256(input_data).hexdigest()
hash_sentinel = args.output_file + '.input_hash'
try:
    with open(hash_sentinel) as f:
        last_hash = f.read().strip()
except FileNotFoundError:
    last_hash = None

if last_hash == input_hash and os.path.exists(args.output_file):
    sys.exit(0)

generated_compile_commands = []

compile_commands = json.loads(input_data)

for entry in compile_commands:
    entry_file = entry['file']
    if not 'UnifiedSource' in entry_file:
        generated_compile_commands.append(entry)
        continue

    # The paths we expect are in the style of:
    # - WebKit/WebKitBuild/Release/DerivedSources/WebKit/unified-sources/UnifiedSource-54928a2b-29.cpp
    # - WebKit/WebKitBuild/Release/WebCore/DerivedSources/unified-sources/UnifiedSource-42f7b70e-5.cpp
    # And Windows too:
    # - WebKit\WebKitBuild\Release\WebCore\DerivedSources\unified-sources\UnifiedSource-42f7b70e-5.cpp
    # So we extract the parent folders to map them to the source folders.
    parent_dir_1, parent_dir_2 = entry_file.rsplit(os.path.sep, maxsplit=4)[1:3]
    search_directories = [
        os.path.join(build_dir, parent_dir_1, parent_dir_2),
    ]

    if parent_dir_1 == 'DerivedSources':
        search_directories.append(os.path.join(source_dir, 'Source', parent_dir_2))
    else:
        search_directories.append(os.path.join(source_dir, 'Source', parent_dir_1))

    with open(entry_file) as f:
        for line in f.readlines():
            include_path = line[10:-2]  # Extract header from `#include "HEADER"\n`
            for d in search_directories:
                include_file = os.path.join(d, include_path)

                if os.path.exists(include_file):
                    renamed_entry = {
                        "directory": entry["directory"],
                        "file": include_file,
                    }

                    if "command" in entry:
                        renamed_entry["command"] = entry["command"].replace(entry_file, include_file)
                    else:
                        renamed_arguments = [arg.replace(entry_file, include_file) for arg in entry["arguments"]]
                        renamed_entry["arguments"] = renamed_arguments

                    generated_compile_commands.append(renamed_entry)
                    break

output_directory = os.path.dirname(args.output_file)
if not os.path.isdir(output_directory):
    os.makedirs(output_directory)

new_content = json.dumps(generated_compile_commands, indent=2)
try:
    with open(args.output_file) as f:
        existing_content = f.read()
except FileNotFoundError:
    existing_content = None

if new_content != existing_content:
    with open(args.output_file, 'w') as f:
        f.write(new_content)

with open(hash_sentinel, 'w') as f:
    f.write(input_hash)