Configure-time guard for known-bad Windows toolchains (#36) - #39
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Two combinations configured and built cleanly while being wrong; both were advisory prose until the test suite (21 s of segfaults) enforced one. - mingw GCC with any AVX2-or-wider target compiled in is now a FATAL_ERROR naming GCC PR 126741, with both escapes in the message: cap to the 128-bit tiers, or CORVUS_ALLOW_UNSUPPORTED_TOOLCHAIN=ON (warns). - Real MSVC is capped at AVX2 by corvus itself — (HWY_AVX3|(HWY_AVX3-1)) OR-ed into HWY_DISABLED_TARGETS — so a change to Highway's blocklist cannot silently widen an unvalidated build. Announced on every MSVC configure (WARNING top-level, NOTICE as a subproject); CORVUS_MSVC_UNBLOCK_AVX512 lifts both caps. - clang-cl and GNU-driver clang pass untouched: the guard keys on the compiler ID, never on CMake's MSVC/MINGW variables. The guard does not parse CORVUS_DISABLED_TARGETS. A two-sided compile probe asks Highway's own HWY_TARGETS whether a wide target survives the cap; it showed the hand-written "HWY_AVX3|HWY_AVX2" is not a 128-bit cap (AVX3_DL/ZEN4/SPR stay compiled) — the false-confidence case the issue warned about. The verdict is a pure function, tested in cmake -P on every leg (mutation-checked); the Windows job gains two configure-only mingw steps that reuse its Highway checkout. Verified locally by widening the system match to Darwin in a scratch copy and configuring with Homebrew g++-16: uncapped -> fatal, 128-bit cap -> OK, partial cap -> fatal, override -> warning. Closes #36 Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
…n the Windows job comment The unquoted $(pkg-config ...) was intentional word splitting, flagged by shellcheck via actionlint. reviewdog reports per touched file, so the pre-existing warning surfaced on this PR. An explicit array keeps the behaviour and states the intent. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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Closes #36.
cmake/ToolchainGuard.cmaketurns two advisory Windows hazards into configure-time behaviour.FATAL_ERRORnaming GCC PR 126741, both escapes in the messageCORVUS_ALLOW_UNSUPPORTED_TOOLCHAIN=ONWARNING(HWY_AVX3|(HWY_AVX3-1))OR-ed intoHWY_DISABLED_TARGETS), announced every configure:WARNINGtop-level,NOTICEas a subprojectCORVUS_MSVC_UNBLOCK_AVX512=ONGNU/MSVConlyNo string parsing. A two-sided compile probe asks Highway's own
HWY_TARGETSwhether a wide target survives the cap. It immediately showed that the hand-written"HWY_AVX3|HWY_AVX2"is not a 128-bit cap —AVX3_DL/AVX3_ZEN4/AVX3_SPRstay compiled — which is the false-confidence case the issue warned about. A broken probe reportsPROBE_FAILEDand is treated as uncapped, never as capped.Why the MSVC cap is explicit: today MSVC tops out at AVX2 only because Highway's
HWY_BROKEN_MSVCsays so. If upstream adds a version floor (#28), an MSVC build would silently start compiling AVX-512 kernels nobody validated. The notice is unconditional rather than host-CPU-dependent because the cap governs what is compiled, and the configure host is often not the run host.Verification
toolchain_guardctest: the verdict function incmake -Pscript mode, every leg, mutation-checked (breaking the Windows match fails 3 verdicts).CORVUS_EXPECT_TARGET=AVX2still holding.No GCC version condition yet — no fixed release exists; #29 is the trigger.
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