fix: probe flag support without OUT_DIR via tempfile - #1875
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NobodyXu merged 3 commits intoSep 1, 2026
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Callers outside Cargo build scripts (e.g. rustc bootstrap) have no OUT_DIR, so flag-support probes errored and unwrap_or(false) silently dropped flags such as -gz. Fall back to unique tempfiles on the probe path only; compile() still requires OUT_DIR. Co-authored-by: Cestercian <yashafaid@gmail.com>
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Thank you! Some feedback on the code
Share check-file extension and contents between ensure_check_file and the OUT_DIR tempfile fallback, and extract probe-dir setup for reuse. Co-authored-by: Cestercian <yashafaid@gmail.com>
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Thank you, just one last comment to be resolved!
Share flush and sync_data with ensure_check_file; keep the tempfile handle drop at the NamedTempfile call site so Windows can open the probe file. Co-authored-by: Cestercian <yashafaid@gmail.com>
This was referenced Sep 4, 2026
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Build::flag_if_supportedqueues flags that are later applied viais_flag_supported_inner(...).unwrap_or(false). The probe writesflag_check.cunderget_out_dir(), which only succeeds whenBuild::out_dir()was set orOUT_DIRis in the environment. Outside a Cargo build script (rustc bootstrap, rust-lang/rust#158169), that lookup errors, every flag is treated as unsupported, and flags such as-gzare silently dropped.get_out_diris unchanged:compile()/ archive output still requireOUT_DIR. Only the flag-support probe falls back to uniqueNamedTempfiles understd::env::temp_dir()when the dir is missing.Changes
is_flag_supported_inner: tempfile fallback whenOUT_DIR/out_diris unset; existingflag_check.creuse whenOUT_DIRis presentTest::gcc_without_out_dirplusflag_if_supported_without_out_dircovering unsetOUT_DIRRelated
Fixes #1765. Bootstrap symptom: rust-lang/rust#158169.
Testing