tree 65f79d1f67600072824b72b92abea10c15a6f963
parent fa161fa85d49f8b054747078ae093aeb77fdf071
author brandjon <brandjon@google.com> 1553632651 -0700
committer Copybara-Service <copybara-worker@google.com> 1553632839 -0700

Implement autodetecting Python toolchain

This replaces the stub default Python toolchain with one that actually locates the target platform's Python interpreter at runtime. Try it out with

    bazel build //some_py_binary --experimental_use_python_toolchains

and note that, unlike before (#4815), the correct Python interpreter gets invoked by default regardless of whether you specify `--python_version=PY2` or `--python_version=PY3`.

This toolchain is only intended as a last resort, if the user doesn't define and register a better toolchain (that satisfies the target platform constraints).

Work toward #7375 and #4815. Follow-up work needed to add a test (#7843) and windows support (#7844).

RELNOTES: None
PiperOrigin-RevId: 240417315