gradio cli cannot reload scripts with utf8-bom encoding

[IceSandwich]

Describe the bug

As saying in this documentation:

By default, the Gradio use UTF-8 encoding for scripts.

But it's not going to work with UTF-8 BOM encoding scripts.

> gradio webui.py
Traceback (most recent call last):
  File "D:\miniconda3\envs\voicelab\lib\threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "D:\miniconda3\envs\voicelab\lib\threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "D:\miniconda3\envs\voicelab\lib\site-packages\gradio\utils.py", line 284, in watchfn
    no_reload_source_code = _remove_if_name_main_codeblock(str(reloader.demo_file))
  File "D:\miniconda3\envs\voicelab\lib\site-packages\gradio\utils.py", line 202, in _remove_if_name_main_codeblock
    tree = ast.parse(code)
  File "D:\miniconda3\envs\voicelab\lib\ast.py", line 50, in parse
    return compile(source, filename, mode, flags,
  File "<unknown>", line 1
    #-*- coding: utf-8 -*-
    ^
SyntaxError: invalid non-printable character U+FEFF
* Running on local URL:  http://127.0.0.1:8000

To create a public link, set `share=True` in `launch()`.
Keyboard interruption in main thread... closing server.

U+FEFF is the identification of UTF-8 BOM encoding.

So, it's a bug?

Have you searched existing issues? 🔎

• I have searched and found no existing issues

Reproduction

#-*- coding: utf-8 -*-
import gradio as gr

Save it in UTF-8 BOM encoding and use gradio to run it.

Screenshot

No response

Logs

System Info

Gradio Environment Information:
------------------------------
Operating System: Windows
gradio version: 5.16.0
gradio_client version: 1.7.0

------------------------------------------------
gradio dependencies in your environment:

aiofiles: 23.2.1
anyio: 4.8.0
audioop-lts is not installed.
fastapi: 0.115.8
ffmpy: 0.5.0
gradio-client==1.7.0 is not installed.
httpx: 0.28.1
huggingface-hub: 0.28.1
jinja2: 3.1.5
markupsafe: 2.1.5
numpy: 1.26.4
orjson: 3.10.15
packaging: 24.2
pandas: 2.2.3
pillow: 10.4.0
pydantic: 2.10.6
pydub: 0.25.1
python-multipart: 0.0.20
pyyaml: 6.0.2
ruff: 0.9.6
safehttpx: 0.1.6
semantic-version: 2.10.0
starlette: 0.45.3
tomlkit: 0.13.2
typer: 0.15.1
typing-extensions: 4.12.2
urllib3: 2.3.0
uvicorn: 0.34.0
authlib; extra == 'oauth' is not installed.
itsdangerous; extra == 'oauth' is not installed.


gradio_client dependencies in your environment:

fsspec: 2025.2.0
httpx: 0.28.1
huggingface-hub: 0.28.1
packaging: 24.2
typing-extensions: 4.12.2
websockets: 11.0.3

Severity

I can work around it