[Formatting] headers and future imports checks

.pre-commit-config.yaml

@@ -49,3 +49,17 @@ repos:
       entry: autoflake --in-place --remove-unused-variables --remove-all-unused-imports
       language: system
       types: [python]
+
+    - id: check-future-annotations
+      name: Check for `from __future__ import annotations`
+      entry: python packaging/check_future_annotations.py
+      language: python
+      files: \.py$
+      exclude: run-clang-format\.py
+
+    - id: check-header
+      name: Check for Meta copyright header
+      entry: python packaging/check_headers.py
+      language: python
+      files: \.py$
+      exclude: run-clang-format\.py

packaging/check_future_annotations.py

@@ -0,0 +1,43 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+from __future__ import annotations
+
+import sys
+
+
+def add_future_import(filename):
+    with open(filename, encoding="utf-8") as f:
+        lines = f.readlines()
+
+    # Check if the import is already present
+    for line in lines:
+        if line.strip() == "from __future__ import annotations":
+            return  # Import already present, no need to modify
+
+    # Find the position to insert the import
+    insert_pos = 0
+    for i, line in enumerate(lines):
+        stripped_line = line.strip()
+        if stripped_line and not stripped_line.startswith("#"):
+            insert_pos = i
+            break
+
+    # Insert the import statement after the first comment block
+    lines.insert(insert_pos, "from __future__ import annotations\n\n")
+
+    # Write the modified lines back to the file
+    with open(filename, "w", encoding="utf-8") as f:
+        f.writelines(lines)
+
+
+def main():
+    files = sys.argv[1:]
+    for f in files:
+        add_future_import(f)
+    print("Processed files to ensure `from __future__ import annotations` is present.")
+
+
+if __name__ == "__main__":
+    main()

packaging/check_headers.py

@@ -0,0 +1,39 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from __future__ import annotations
+
+import sys
+
+HEADER = """# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+"""
+
+
+def check_header(filename):
+    with open(filename, encoding="utf-8") as f:
+        file_content = f.read()
+
+    if not file_content.startswith(HEADER):
+        print(f"Missing or incorrect header in {filename}")
+        return False
+    return True
+
+
+def main():
+    files = sys.argv[1:]
+    all_passed = True
+    for f in files:
+        if not check_header(f):
+            all_passed = False
+    if not all_passed:
+        sys.exit(1)
+    sys.exit(0)
+
+
+if __name__ == "__main__":
+    main()