Reserve an 8 MiB main-thread stack on Windows - #94
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Windows gives the main thread 1 MiB; Linux and macOS give it 8 MiB. Building clap's command tree for this many subcommands needs just under 1 MiB in an unoptimized build (measured with `ulimit -s` on 2026-09-06: main fails below 1024 KiB on macOS too), so adding a single flag to `message` (#90, #91) made every debug and test invocation on Windows, `--help` included, die with `thread 'main' has overflowed its stack`, and `cargo test --all-targets` failed on windows-latest only. A build script now passes `/STACK:8388608` to the MSVC linker (and `--stack` to the GNU one). This is the approach rustup takes for the same clap behaviour (clap-rs/clap#5134), and unlike a `.cargo/config` rustflags entry it survives CI setting `RUSTFLAGS`. The reservation is address space, not committed memory. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WG7vFLjFZHqAUMRS1zkWRE
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Proof: #90 was rebased onto this branch and its |
This was referenced Sep 6, 2026
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Problem
Windows gives the main thread 1 MiB of stack; Linux and macOS give it 8 MiB. Building clap's derived command tree for this many subcommands needs just under 1 MiB in an unoptimized build, so
mainis already at the edge: adding one flag tomessage(#90, #91) made every debug and test invocation ofteamson Windows,--helpincluded, fail withand
cargo test --all-targetsfailed onwindows-latestonly (both PRs' CI runs), while #92 and #93, which do not touchmessage, passed.Measured locally with
ulimit -s:main, #90 and #91 all fail below 1024 KiB on macOS as well, in every startup phase including--help-json, which only builds the command tree.Fix
A
build.rspasses/STACK:8388608to the MSVC linker (--stackon the GNU toolchain) for Windows targets, which matches the Unix defaults. This is what rustup does for the same clap behaviour (clap-rs/clap#5134). A build script survives CI overridingRUSTFLAGS, which a.cargo/config.tomlrustflagsentry would not. The reservation is address space, not committed memory.Verification
mainpasses on Windows with or without this change, so the proof is #90: it is rebased onto this branch and itswindows-latestjob goes green with the same code that failed before.🤖 Generated with Claude Code
https://claude.ai/code/session_01WG7vFLjFZHqAUMRS1zkWRE