tree 97e071d7f3a6e6c11d98a571242b356a25ae24ab
parent 693a1587baf055979493565933f8f40225c00c6d
author Richard Levasseur <rlevasseur@google.com> 1703020902 -0800
committer Richard Levasseur <rlevasseur@google.com> 1703020902 -0800

fix: register autodetecting toolchain automatically

@bazel_tools depends on rules_python, but the version is currently
specifies (0.22.0) doesn't register a toolchain by default. This means
the Bazel builtin Python rules aren't usable because no toolchain
is registered for them.

Registering the toolchain directly in @bazel_tools inverts the problem:
a toolchain is now always registered, but will usually always have
precedence over any that rules_python registers (because @bazel_tools
typically comes earlier in the module graph ordering).

Upgrading bazel_tools past to 0.23.0 or higher (which register a Python
toolchain automatically) is possible, but results in many failures in
Bazel CI that are hard to figure out.

To fix, we make rules_python register the autodetecting toolchain.
Later rules_python versions register a different toolchain, but this
at least gives Bazel something it can set as the minimum version that
preserves existing behavior.

Work towards https://github.com/bazelbuild/bazel/issues/20458