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🐛 fix(backend): escape output the stdout encoding cannot represent - #330
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gaborbernat merged 4 commits intoOct 28, 2026
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The backend prints its module and the hook arguments, which include project and output paths. Before Python 3.15 a Windows pipe uses the ANSI code page, so a path such as a Cyrillic folder name made print() raise UnicodeEncodeError and the build failed. Use backslashreplace for stdout, as stderr already does.
ty needs the suppression because typeshed declares sys.stdout as TextIO, which has no reconfigure(). Inline the single-use frontend in the test.
gaborbernat
changed the title
The fix lives in the backend module, so its test belongs in the backend test file, importing the frontend from the public package.
gaborbernat
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October 28, 2026 01:12
gaborbernat
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October 28, 2026 01:29
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On Windows,
SubprocessFrontendandpython -m pyproject_apifailed when a path the backend prints contains a character outside the ANSI code page, for example a project in a Cyrillic folder on an English-locale machine. Python writes pipes in the ANSI code page on Windows, so the backend's progress messages raisedUnicodeEncodeErrorand the build stopped with a missing response file:🐛 The backend now writes such characters to standard output as backslash escapes, the same error handler Python already uses for standard error. This is the encoding-side counterpart of #311, which made the frontend tolerate bytes it cannot decode. tox is not affected because it sets
PYTHONIOENCODING=utf-8for the processes it runs.The setting applies only when the backend runs as its own process, so callers that import the backend module in-process keep their stream configuration.