Draft: select native compilers from the C++ toolchain for sdist wheel builds

[xangcastle]

No description provided.

[aspect-workflows]

✨ Aspect Workflows Tasks

📅 Tue Jun 23 07:57:56 UTC 2026

❌ 2 failed tasks

• ❌ test (test-e2e-bazel-9) · ⏱ 34.5s · 🐙 GitHub Actions · ☑️ Check
  💬 failed in test · Bazel test failed
• ❌ test (test-root-bazel-9) · ⏱ 22s · 🐙 GitHub Actions · ☑️ Check
  💬 failed in test · Bazel test failed

✅ 5 successful tasks

• ✅ buildifier · ⏱ 18.9s · 🐙 GitHub Actions · ☑️ Check
  💬 Format complete (clean)
• ✅ gazelle · ⏱ 22.8s · 🐙 GitHub Actions · ☑️ Check
  💬 Gazelle complete (clean)
• ✅ test (test-e2e-bazel-8) · ⏱ 2m 1s · 🐙 GitHub Actions · ☑️ Check
  💬 Bazel test complete (160/160 passed)
• ✅ test (test-examples-uv_pip_compile-bazel-8) · ⏱ 30s · 🐙 GitHub Actions · ☑️ Check
  💬 Bazel test complete (1/1 passed · 1 cached)
• ✅ test (test-root-bazel-8) · ⏱ 1m 53s · 🐙 GitHub Actions · ☑️ Check
  💬 Bazel test complete (209/209 passed)

🔁 Reproduce

❌ test (test-e2e-bazel-9 · test-root-bazel-9)

aspect test -- //...

# vanilla bazel
bazel test -- //...

_{Install aspect: docs.aspect.build/cli/install}

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[tamird]

I do not think CcToolchainInfo exposes a reusable compiler-command
contract for arbitrary PEP 517 backends. Bazel's configured compile and link
actions have Bazel C++ semantics; distutils, Meson, CMake, and other backends
own different driver and linker behavior after changing into the source tree.
Projecting those actions requires the sysroot, token, driver, and path
heuristics this change has accumulated.

#1152 removes that projection. Packages declare build_toolchains and env
explicitly; rules_py forwards their inputs and Make variables, makes only
exact whole-value declared tool paths absolute before chdir, and leaves all
other values opaque.