Specify encoding in open

[Avasam]

See https://peps.python.org/pep-0597/
This also happened to me on Windows in python/typeshed#8879 because of mathematical unicode characters as part of the comments:

(.venv) PS C:\Users\Avasam\Documents\Git\typeshed> flake8 .                    
Traceback (most recent call last):
  File "C:\Program Files\Python39\lib\runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Program Files\Python39\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\Scripts\flake8.exe\__main__.py", line 7, in <module>
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\main\cli.py", line 22, in main
    app.run(argv)
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\main\application.py", line 363, in run
    self._run(argv)
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\main\application.py", line 351, in _run
    self.run_checks()
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\main\application.py", line 264, in run_checks
    self.file_checker_manager.run()
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\checker.py", line 323, in run
    self.run_serial()
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\checker.py", line 307, in run_serial
    checker.run_checks()
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\checker.py", line 589, in run_checks
    self.run_ast_checks()
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\flake8\checker.py", line 494, in run_ast_checks
    for (line_number, offset, text, _) in runner:
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\pyi.py", line 1811, in run
    yield from _check_for_type_comments(path)
  File "C:\Users\Avasam\Documents\Git\typeshed\.venv\lib\site-packages\pyi.py", line 1777, in _check_for_type_comments
    stublines = path.read_text().splitlines()
  File "C:\Program Files\Python39\lib\pathlib.py", line 1267, in read_text     
    return f.read()
  File "C:\Program Files\Python39\lib\encodings\cp1252.py", line 23, in decode 
    return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x90 in position 176166: 
character maps to <undefined>

There are linters to catch this, namely pylint (unspecified-encoding), flake8-encodings and flake8-file-encoding. I have tried both flake8 plugins mentioned and they gave me the same results, other than slightly different error messages:

[AlexWaygood]

I'm fine with these changes, but they won't fix the error you're seeing locally when you run flake8 on python/typeshed#8879! To fix that error, you need to add encoding="utf-8" to the call to read_text here:

flake8-pyi/pyi.py

Line 1777 in c55a904

stublines = path.read_text().splitlines()

Wanna do that in this PR as well?

[AlexWaygood]

Thanks! Want to add a changelog entry? This counts as a bugfix. (Feel free to give yourself credit in the entry.)

[Avasam]

Thanks! Want to add a changelog entry? This counts as a bugfix. (Feel free to give yourself credit in the entry.)

Are there guidelines on how to do so? CONTRIBUTING.md mentions doing a release, which I don't think is quite what I want.

[AlexWaygood]

Are there guidelines on how to do so?

No, we don't have guidelines for that yet -- I can write something up :) But basically the process is "add a short sentence to the top of the changelog describing the user-visible impact of the change".

For now, this is is a pretty good example of a bugfix changelog entry: https://github.com/PyCQA/flake8-pyi/pull/193/files#diff-06572a96a58dc510037d5efa622f9bec8519bc1beab13c9f251e97e657a9d4edR3-R6

And this is a pretty good example of a changelog entry from a non-maintainer contributor: https://github.com/PyCQA/flake8-pyi/pull/242/files#diff-06572a96a58dc510037d5efa622f9bec8519bc1beab13c9f251e97e657a9d4edR20-R21

[AlexWaygood]

Gonna pretend I know what a non-CP1252 character is

[Avasam]

Gonna pretend I know what a non-CP1252 character is

CP1252 character set, aka Windows-1252 character set. Is the default windows one.

Python lists it as cp1252

[AlexWaygood]

Thanks! :D