feat(pex): use exec interpreter for PEX builds, enabling cross-builds#880
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feat(pex): use exec interpreter for PEX builds, enabling cross-builds#880
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whl_install's compile_pyc uses `py_toolchain.interpreter` which is resolved in target configuration. In cross-arch builds, the target interpreter is not runnable on the build host. Add a `resolved_py_toolchain` rule (analogous to `resolved_unpack_toolchain`) that re-exports the Python toolchain, and reference it via `cfg="exec"` so compileall gets a host-runnable interpreter. This is safe because .pyc bytecode depends on Python version, not architecture. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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…#618) The PEX builder was being passed the target platform's interpreter, which fails in cross-builds (e.g. building a Linux PEX on macOS) with "Exec format error". Since rules_py already controls dependency resolution hermetically, the PEX builder doesn't need the target interpreter — it just needs to run on the build host. Remove the --python flag from py_pex_binary and let PEXBuilder use the current (cfg=exec) interpreter instead. Based on the work by Peter Lobsinger in #618. Co-Authored-By: Peter Lobsinger <peter@tecton.ai> Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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…#881) When `compile_pyc` is enabled, `whl_install` invokes `compileall` using `py_toolchain.interpreter` which is resolved in **target** configuration. In cross-arch builds (e.g. x86 host building for arm64), the target interpreter isn't runnable on the build host, causing the action to fail. This adds a `resolved_py_toolchain` rule (following the existing `resolved_unpack_toolchain` pattern) and references it via `cfg="exec"` so compileall gets a host-runnable interpreter. This is safe because `.pyc` bytecode depends on Python version, not architecture. ### Changes are visible to end-users: no ### Test plan - Covered by existing test cases - Cross-arch scenario validated in #880 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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Takes over #618. The PEX builder previously required a target-configured Python interpreter, which fails in cross-arch builds since the target interpreter isn't runnable on the build host.
The fix removes the
--pythonargument entirely —PEXBuilder(interpreter=None)works because rules_py already controls dependency resolution hermetically; PEX doesn't need to probe the interpreter for platform compatibility.Also adds cross-arch
build_testtargets validating PEX builds for bothlinux_arm64andlinux_amd64viaplatform_transition_filegroup.Closes #618.
Changes are visible to end-users: yes
py_pex_binarynow supports cross-architecture builds (e.g. building an arm64 PEX on an x86 host).Test plan
build_testtargets addedpy-pex-binarye2e tests pass🤖 Generated with Claude Code