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Switch flate2 to the zlib-rs backend - #1020
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The `zlib-rs` backend is the fastest `flate2` backend, and being pure Rust it doesn't depend on a C toolchain, so cross-compiles without issue (unlike `zlib-ng`). See: - https://github.com/rust-lang/flate2-rs#backends - https://trifectatech.org/blog/zlib-rs-is-faster-than-c/ The `runtime_detection` feature has to be enabled explicitly, since it's one of the default features disabled by `default-features = false`, and is required for runtime CPU feature detection (and so SIMD acceleration) in `zlib-rs`. This also unblocks buildpacks that use the `tar` feature from switching to `zlib-rs` themselves, since when both features are enabled `zlib` takes precedence over `zlib-rs`. GUS-W-24154015.
edmorley
marked this pull request as ready for review
October 2, 2026 13:26
edmorley
enabled auto-merge (squash)
October 2, 2026 13:27
runesoerensen
approved these changes
Oct 2, 2026
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The
zlib-rsbackend is the fastestflate2backend, and being pure Rust it doesn't depend on a C toolchain, so cross-compiles without issue (unlikezlib-ng). See:The
runtime_detectionfeature has to be enabled explicitly, since it's one of the default features disabled bydefault-features = false, and is required for runtime CPU feature detection (and so SIMD acceleration) inzlib-rs.This also unblocks buildpacks that use the
tarfeature from switching tozlib-rsthemselves, since when both features are enabledzlibtakes precedence overzlib-rs.GUS-W-24154015.