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deps(mimalloc): set MI_OVERRIDE=OFF on Windows #29467

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Merged
dylan-conway merged 2 commits into from
Apr 18, 2026
Merged

deps(mimalloc): set MI_OVERRIDE=OFF on Windows #29467

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deps(mimalloc): set MI_OVERRIDE=OFF on Windows
dylan-conway Apr 18, 2026
1432ab3
deps(mimalloc): add Windows row to override decision matrix
dylan-conway Apr 18, 2026
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9 changes: 7 additions & 2 deletions scripts/build/deps/mimalloc.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -83,9 +83,14 @@
args.MI_OVERRIDE = "ON";
args.MI_OSX_ZONE = "OFF";
args.MI_OSX_INTERPOSE = "OFF";
} else if (cfg.windows) {
// Bun links the static CRT and calls mi_* directly; nothing routes
// through CRT malloc. With override ON, dev3's alloc-override.c
// emits _expand/_msize/free into the static lib and lld-link
// duplicates against libucrt(d). mimalloc's *default* is ON, so
// this must be explicit.
args.MI_OVERRIDE = "OFF";
}

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Claude / Claude Code Review

Decision matrix comment omits Windows entry 

The decision matrix comment (lines 61–68) lists ASAN, macOS, and Linux override policies but omits a Windows entry, even though this PR adds an explicit `cfg.windows` branch setting `MI_OVERRIDE=OFF`. A reader consulting the matrix to understand Windows override policy would find no entry there; they must discover the rationale from the inline comment deeper in the function.
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claude[bot] marked this conversation as resolved.
// Windows: use mimalloc's defaults (no override; Windows has its own
// mechanism via the static CRT we link).

if (cfg.debug) {
// Heavy debug checks: guard bytes, freed-memory poisoning, double-free
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