ci(macos): drop -stack_size rustflag (breaks proc-macro dylib links)#294
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Follow-up to #293. Replacing `-undefined dynamic_lookup` with `-Wl,-stack_size,0x800000` fixed the dyld crash but introduced a new build failure: ld64 rejects `-stack_size` on any link that is not a main executable — ld: -stack_size option can only be used when linking a main executable cargo applies rustflags to every link invocation, including proc-macro/cdylib crates (e.g. serde_derive, linked `-dynamiclib`), so the flag fails the build before any test runs. On Linux the equivalent `-zstack-size` is silently accepted for shared objects, which is why it was never caught there. macOS already defaults the main-thread stack to 8 MB — the same value the Linux side sets explicitly — so no override is needed. Drop the custom rustflags on macOS entirely. Claude-Session: https://claude.ai/code/session_01Vnu2A87mWaKnbeFuWZSwkd
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Follow-up to #293
#293 removed
-undefined dynamic_lookup(which caused the dyldsyscall to map cache into shared region failed/ SIGABRT crash) and replaced it with-Wl,-stack_size,0x800000to preserve the Linux side's 8 MB stack intent. That replacement introduced a new build failure on macOS:Cause
ld64rejects-stack_sizeon any link target that isn't a main executable. Cargo appliesrustflagsto every link invocation — including proc-macro and cdylib crates likeserde_derive, which link as-dynamiclib. So the flag fails the build before a single test runs. On Linux the equivalent-zstack-sizeis silently accepted for shared objects, which is why the same pattern was never a problem there.Fix
Drop the custom
rustflagson macOS entirely. The macOS main-thread stack already defaults to 8 MB — the exact value the Linux side sets explicitly via-zstack-size=8388608— so no override is needed. (The-stack_sizelinker arg only affects the main thread anyway;cargo testruns tests on spawned worker threads, so it never influenced the test suite.)The step now writes only
linker = "clang"(the macOS default) plus a comment documenting both flags that must not come back.Verification
Confirmed on PR #244's runner: with #293 merged, the dyld crash is gone and the build now fails only on this
-stack_sizeerror — this PR removes that last flag. The same fix is already pushed to the #244 branch, which is re-running CI now.https://claude.ai/code/session_01Vnu2A87mWaKnbeFuWZSwkd