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[3.14] gh-159739: Validate newline replacement in TextIOWrapper.write (GH-160191) - #160487
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….write (pythonGH-160191) A str subclass can override replace() and return a non-string while TextIOWrapper.write() translates newlines. The C implementation then treats the result as Unicode and can crash. Reject an invalid replacement with TypeError. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_io.py. (cherry picked from commit c6796a1) Co-authored-by: Jelle Zijlstra <jelle@openai.com>
This was referenced Oct 23, 2026
JelleZijlstra
marked this pull request as ready for review
October 23, 2026 20:35
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A str subclass can override replace() and return a non-string while TextIOWrapper.write() translates newlines. The C implementation then treats the result as Unicode and can crash. Reject an invalid replacement with TypeError. Backport to 3.15 and 3.14; on 3.14, put the regression test in Lib/test/test_io.py.
(cherry picked from commit c6796a1)
Co-authored-by: Jelle Zijlstra jelle@openai.com
Backport of #160191 to 3.14.
Move the two regression tests into 3.14's
Lib/test/test_io.py.Ran
test_ioon a free-threaded 3.14 build, including invalid replacement results and callbacks that change the stream state.