Build for iOS (aarch64-apple-ios) is broken

[olliiiver]

Hello.

It seems I cannot build the SDK for aarch64-apple-ios.

I've added a pipeline to demonstrate this here:

https://github.com/olliiiver/matrix-rust-sdk-build/actions/runs/12320983696/job/34391426770

The error message is:

  = note: ld: warning: object file (/Users/runner/work/matrix-rust-sdk-build/matrix-rust-sdk-build/matrix-rust-sdk/target/aarch64-apple-ios/debug/deps/libblake3-e40b55db2257280c.rlib[6](db3b6bfb95261072-blake3_neon.o)) was built for newer 'iOS' version (17.5) than being linked (10.0)
          Undefined symbols for architecture arm64:
            "___chkstk_darwin", referenced from:
                _blake3_hash4_neon in libblake3-e40b55db2257280c.rlib[6](db3b6bfb95261072-blake3_neon.o)
          ld: symbol(s) not found for architecture arm64
          clang: error: linker command failed with exit code 1 (use -v to see invocation)

How can this be fixed?

[zzorba]

Seems like neon might not be available on all arm64 platforms, according to the blake3 documentation https://docs.rs/blake3/latest/blake3/

[olliiiver]

Hi @zzorba ,

looks like this is a blake3 build issue.

I've added a ticket here as well:

BLAKE3-team/BLAKE3#437

[bnjbvr]

For what it's worth, we at Element are building the aarch64-ios SDK with optimizations, as it seems to trigger dead code elimination, and remove usage of this symbol. It's an unfortunate workaround, and we'd be super happy to have a better fix for this, in case any of you has a better understanding of the issue or idea :)

[olliiiver]

Hi @bnjbvr @zzorba . Thanks for coming back to me. Yes, the build (currently) works by using the following workaround:

export CARGO_FEATURE_NO_NEON=1
cargo build --target aarch64-apple-ios