CI: skip llvm-tools-preview install for tests-nocoverage jobs#14967
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llvm-tools (llvm-profdata/llvm-cov) is only used by noxfile.py's process_rust_coverage, which the tests-nocoverage session never calls. Installing the component costs ~10s on the Windows jobs, and the Windows 3.9 tests-nocoverage job is the longest job in the whole CI run, so this is time saved directly on the critical path. https://claude.ai/code/session_014StKTjk7GBcVdiWKimEsQb
reaperhulk
approved these changes
Jun 7, 2026
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What
Skips
rustup component add llvm-tools-previewwhen the nox session istests-nocoverage(linux matrix condition + windows-tests composite action).Why
llvm-tools(llvm-profdata/llvm-cov) is only used byprocess_rust_coverageinnoxfile.py, whichtests-nocoveragenever calls (it neither sets-Cinstrument-coveragenor processes profraw files).From recent CI timing data, the
windows (x64, 3.9, tests-nocoverage)job is consistently the longest job in the entire CI run (~6.4 min; the whole run's wall time tracks it), and it spends ~10s downloading/installing this unused component. Thewindows-11-armand linuxpypy-3.11tests-nocoverage jobs save the same.Small, but it comes straight off the critical path of every CI run.
https://claude.ai/code/session_014StKTjk7GBcVdiWKimEsQb
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