Explicitly select free-threading Python

[fschulze]

I would like to be able to use py313t in the envlist to explicitly run python3.13t as a free-threaded nogil build in addition to py313 which would run python3.13 as an explicitly regular build.

Is there already some way to do that which I missed?

Currently py313t seems to use python.

Related:

• virtualenv is not able to detect free-threading python3.13t pypa/virtualenv#2776

[gaborbernat]

Someone needs to add this functionality first inside virtualenv, or UV if you're ok using tox-uv...

[gaborbernat]

You can always use https://tox.wiki/en/4.21.2/cli_interface.html#tox-run---discover in the meantime to force it...

[ssbarnea]

IMHO that would likely be the most useful tox change to implement because 3.13t is very near and a major source of bugs. Making easy for people to test it with tox would be... very useful.

[gaborbernat]

PR welcome.

[fschulze]

Thanks for the pointer to --discover, that might already be enough for me. Will try later.