No matching toolchains when using `current_py_cc_headers` with WORKSPACE.

[lalten]

🐞 bug report

Description

Can not use @rules_python//python/cc:current_py_cc_headers in WORKSPACE mode because the toolchain fails to resolve. The WORKSPACE file is setting up a hermetic interpreter via python_register_toolchains.

Note that the target works as expected when using a MODULE.bazel.

🔬 Minimal Reproduction

See repro repo: https://github.com/lalten/current_py_cc_headers

🔥 Exception or Error

@@rules_python//python/cc:current_py_cc_headers (5b7f3da): No matching toolchains found for types @@rules_python//python/cc:toolchain_type.

🌍 Your Environment

Operating System: ubuntu-latest
Output of bazel version: 7.0.0
Rules_python version: 0.27.1

[rickeylev]

Ah, i think what's happening is the workspace code path registers a specific target instead of :all (which is what bzlmod does). https://github.com/bazelbuild/rules_python/blob/main/python/repositories.bzl#L583

Should be a simple fix to have it register the additional toolchain.

In the meantime, you can work around this by adding native.register_toolchain() to your workspace. Something like @<name>_toolchains//:all, where <name> is the name of the python runtime repo that was used (usually @python or @python_3_11). Or register the specific platforms you're interested by doing using @<name>_toolchains//<platform>_toolchain, where<platform> would be e.g. linux_x86_64