gh-126004: fix positions handling in codecs.replace_errors

[picnixz]

• Issue: Incorrect handling of start and end values in codecs error handlers #126004

[vstinner]

LGTM

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot iOS ARM64 Simulator 3.x has failed when building commit 225296c.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1380/builds/2419) and take a look at the build logs.
4. Check if the failure is related to this commit (225296c) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1380/builds/2419

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 Android 3.x has failed when building commit 225296c.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1594/builds/1124) and take a look at the build logs.
4. Check if the failure is related to this commit (225296c) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1594/builds/1124

Failed tests:

• test_android

Failed subtests:

• test_bytes - test.test_android.TestAndroidOutput.test_bytes

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/data/user/0/org.python.testbed/files/python/lib/python3.14/test/test_android.py", line 63, in assert_log
    line = self.logcat_queue.get(timeout=(deadline - time()))
  File "/data/user/0/org.python.testbed/files/python/lib/python3.14/queue.py", line 212, in get
    raise Empty
_queue.Empty


Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/base_events.py", line 687, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/Volumes/InternalDisk/Users/android/buildarea/3.x.mhsmith-android-aarch64/build/Android/android.py", line 531, in run_testbed
    async with asyncio.TaskGroup() as tg:
  File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/taskgroups.py", line 134, in __aexit__
    raise propagate_cancellation_error
  File "/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/taskgroups.py", line 110, in __aexit__
    await self._on_completed_fut
asyncio.exceptions.CancelledError


Traceback (most recent call last):
  File "/data/user/0/org.python.testbed/files/python/lib/python3.14/test/test_android.py", line 53, in setUp
    self.assert_log("I", tag, message, skip=True, timeout=5)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/user/0/org.python.testbed/files/python/lib/python3.14/test/test_android.py", line 65, in assert_log
    self.fail(f"line not found: {expected!r}")
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: line not found: 'test.test_android.TestAndroidOutput.test_bytes 1737630241.1795416'

[picnixz]

The iOS failures seem unrelated though I cannot confirm and the Android failure may be related so I'll check

[picnixz]

The code that seems to fail is:

self.assertEqual(write_len, stream.write(b))
if lines is None:
    lines = [b.decode()]
self.assert_logs(level, tag, lines)

However, we're using a strict or a backslashreplace error handler in b.decode() and the logcat process:

    def setUp(self):
        self.logcat_process = subprocess.Popen(
            ["logcat", "-v", "tag"], stdout=subprocess.PIPE,
            errors="backslashreplace"
        )

so I don't know how it was affected by this change. I'll rerun the build bot for this one and if it still fails, I'll revert the PR.

[picnixz]

!buildbot aarch64 Android 3.x

[bedevere-bot]

The regex 'aarch64 Android 3.x' did not match any buildbot builder. Is the requested builder in the list of stable builders?

[picnixz]

Nevermind, the two build bots are actually green on the latest main ¯\_(ツ)_/¯

[mhsmith]

I'm not sure what happened with the iOS buildbot, but the Android failure is a known problem: #124666.

[picnixz]

Thank you for confirming this. iOS build bot seems to never run so it could be a network issue or build bot issue.

[mhsmith]

The iOS buildbot had some issues recently (#129200), but it should be back to normal now. This particular failure is one I haven't seen before – it looks like it passed the test suite and then crashed at the end.