tree 3ffccdda378b059f594ab06767ef896c9547467b
parent 1bce7544dab8d6e9083a5b40d0f303c65ece200b
author brandjon <brandjon@google.com> 1559677771 -0700
committer Copybara-Service <copybara-worker@google.com> 1559677854 -0700

Warn in more cases of possible Python version mismatch in host config

We already emit a diagnostic message when the host config's Python version overrides a Python tool's normal version. This helps users know to add --host_force_python=PY2 to their bazelrc. Without it, all they'd see is a confusing Python stack trace.

With this change, we also emit a diagnostic message when the target's python_version attribute is omitted and the user has not set --host_force_python=PY2. This covers the case where both the target and the host config default to PY3, but the target was really intended to be a Python 2 target. Previously, this case sometimes worked anyway due to #4815, but with Python toolchains enabled it breaks and we need to help the user understand the breakage.

In all cases the diagnostic is still only printed when the target has non-zero exit code and is built in host config.

See also #7899. Fixes #8549.

RELNOTES: None
PiperOrigin-RevId: 251496135