PEP723 metadata reader uses default encoding

[gertjanvanzwieten]

Description

The routine that parses PEP723 metadata opens the script file without specifying the encoding. This causes pip install --requirements-from-script to fail if the script contains characters that fail to decode against the current locale encoding, resulting in a UnicodeDecodeError.

Expected behavior

The spec states that "Tools reading embedded metadata MAY respect the standard Python encoding declaration. If they choose not to do so, they MUST process the file as UTF-8." I therefore believe that specifying the UTF-8 encoding if sufficient to become compliant.

pip version

26.0.1

Python version

any <= 3.14

OS

mostly likely to occur on windows

How to Reproduce

1. Create a script containing the non-ascii character "←" and save it as bug.py with encoding UTF-8
2. Set the platform locale to cp1252 (the Windows default)
3. Run pip install --requirements-from-script bug.py

Output

ERROR: Exception:
Traceback (most recent call last):
  File "C:\hostedtoolcache\windows\Python\3.14.3\x64\Lib\site-packages\pip\_internal\cli\base_command.py", line 107, in _run_wrapper
    status = _inner_run()
  File "C:\hostedtoolcache\windows\Python\3.14.3\x64\Lib\site-packages\pip\_internal\cli\base_command.py", line 98, in _inner_run
    return self.run(options, args)
           ~~~~~~~~^^^^^^^^^^^^^^^
  File "C:\hostedtoolcache\windows\Python\3.14.3\x64\Lib\site-packages\pip\_internal\cli\req_command.py", line 96, in wrapper
    return func(self, options, args)
  File "C:\hostedtoolcache\windows\Python\3.14.3\x64\Lib\site-packages\pip\_internal\commands\install.py", line 358, in run
    reqs = self.get_requirements(args, options, finder, session)
  File "C:\hostedtoolcache\windows\Python\3.14.3\x64\Lib\site-packages\pip\_internal\cli\req_command.py", line 356, in get_requirements
    script_metadata = pep723_metadata(script)
  File "C:\hostedtoolcache\windows\Python\3.14.3\x64\Lib\site-packages\pip\_internal\req\pep723.py", line 18, in pep723_metadata
    script = f.read()
  File "C:\hostedtoolcache\windows\Python\3.14.3\x64\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 7948: character maps to <undefined>

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[ichard26]

Fixed by #13862. Thanks!