Missing `@@_builtins` providers when using pinned toolchains

[tpasternak]

🐞 bug report

Is this a regression?

probably not

Description

A clear and concise description of the problem...

🔬 Minimal Reproduction

Just use this repo:

     File: BUILD.bazel
   1 load("@python_versions//3.12:defs.bzl", "py_binary")
   2 #load("@rules_python//python:defs.bzl", "py_binary")
   3 
   4 py_binary(
   5     name = "main",
   6     srcs = ["main/main.py"],
   7 )

     File: MODULE.bazel
   1 bazel_dep(
   2     name = "rules_python",
   3     version = "0.34.0",
   4 )
   5 
   6 python = use_extension("@rules_python//python/extensions:python.bzl", "python")
   7 python.toolchain(
   8     python_version = "3.12",
   9 )
  10 use_repo(python, "python_versions")

     File: main/main.py   <EMPTY>

🔥 Exception or Error

The BUILD.bazel file contains two different load statements. Depending on which one is enabled, a different set of providers is exposed

When "@rules_python//python:defs.bzl" is on, you get

% bazelisk cquery --output=starlark --starlark:expr="providers(target).keys()" //:main
INFO: Analyzed target //:main (2 packages loaded, 4 targets configured).
INFO: Found 1 target...
["LicenseInfo", "InstrumentedFilesInfo", "RunEnvironmentInfo", "@@rules_python~//python/private/common:providers.bzl%PyRuntimeInfo", "@@_builtins//:common/python/providers.bzl%PyRuntimeInfo", "@@rules_python~//python/private/common:providers.bzl%PyCcLinkParamsProvider", "@@rules_python~//python/private/common:providers.bzl%PyInfo", "@@_builtins//:common/python/providers.bzl%PyInfo", "FileProvider", "FilesToRunProvider", "OutputGroupInfo"]
INFO: Elapsed time: 0.477s, Critical Path: 0.00s
INFO: 0 processes.
INFO: Build completed successfully, 0 total actions

on the other hand, when "@python_versions//3.12:defs.bzl" is, you get

% bazelisk cquery --output=starlark --starlark:expr="providers(target).keys()" //:main
INFO: Analyzed target //:main (63 packages loaded, 1010 targets configured).
INFO: Found 1 target...
["LicenseInfo", "@@rules_python~//python/private/common:providers.bzl%PyInfo", "@@rules_python~//python/private/common:providers.bzl%PyRuntimeInfo", "InstrumentedFilesInfo", "RunEnvironmentInfo", "FileProvider", "FilesToRunProvider", "OutputGroupInfo"]
INFO: Elapsed time: 0.492s, Critical Path: 0.00s
INFO: 0 processes.
INFO: Build completed successfully, 0 total actions

Unfortunately, the latter one doesn't contain "@@rules_python~//python/private/common:providers.bzl%PyInfo", hence in IntelliJ we can't recognize it as a python target.

Screen.Recording.2024-08-09.at.09.54.53.mov

🌍 Your Environment

Operating System:

  
Fedora
  

Output of bazel version:

  
7.2.1
  

Rules_python version:

  
0.34
  

Anything else relevant?
"@python_versions//3.12:defs.bzl" seems to provide an extra target, named //:_main` which contains the expected providers

[rickeylev]

Thanks for the report.

This looks like an easy fix. When X.Y/defs.bzl is used, it's using the py_binary in python/config_settings/transition.bzl, which only includes one of the two PyInfo objects, giving preference to the non-builtin on. It's easy to make it forward along both.

However, the intellij plugin needs to be updated to handle the @rules_python provider. The @_builtins provider will be going away eventually. It should recognized both, giving preference to the @rules_python one.

[tpasternak]

Thank you for fixing it so quickly! We're aware that built-in providers will no longer be available in Bazel 8. However now we plan to overcome this problem with the --incompatible_autoload_externally flag