Python 3

To see a summary of our current position on Python 3 support, see SupportedPythonVersions#Python_3.x_support.

This is a status page for keeping track of what needs to be done to make progress on Mercurial on Python 3.

Nobody is actively working on this - AugieFackler works on it sporadically, and would be happy to see patches on this topic flagged with Py3 on the mailing list. The work in progress is visible at http://hg.durin42.com/hg-py3k/ - note that ChangesetEvolution is in use on that repository, and so hashes will change over time as the patchset is rebased.

1. What Works

run-tests.py can pass its own tests (test-run-tests.py and test-run-tests.t) under 2.6, 2.7 and 3.5.

2. Next Steps

• Eliminate all Python 3 compatibility warnings from test-check-py3-compat.t

• Get the entire codebase working with 'from future import absolute_import'

  • This requires fixing some cyclic imports. See test-check-module-imports.t for currently whitelisted cyclic imports.

• Make existing modules at least parse with Python 3 (still some Python 2.x syntax)
• Remove 2to3 and have the source be 2.6/2.7/3.5 compatible
• Conditionalize imports for renamed modules
• Get the C extensions compiling correctly in Python 3

• Start adding b and u everywhere and using 'from future import unicode_literals'