fix(build): build with Xcode 27 / Swift 6.4 - #172
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- Bump mlx-swift to SharpAI/mlx-swift#16. Metal 4.1 (Xcode 27) no longer treats `this` as `thread` in member functions, which broke 17 of 40 MLX kernels, including all quantized matmuls, so mlx.metallib failed to build. - build.sh: Swift 6.4 builds into .build/out/Products/Release, not .build/arm64-apple-macosx/release. Ask SwiftPM for the bin dir with `--show-bin-path`, and copy the metallib there as mlx.metallib. MLX loads a colocated mlx.metallib first, so it takes priority over the partial default.metallib in mlx-swift_Cmlx.bundle. default.metallib is still copied for mlx-c. - Scripts and tests: use .build/release/SwiftLM, which is a symlink to the real bin dir on both the old and new SwiftPM layouts. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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September 24, 2026 03:22
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Problem
./build.shfails on a fresh macOS 27.0 machine (an M6 Mac mini) with Xcode 27 and Swift 6.4. There are two separate problems:thisinside a member function no longer defaults to thethreadaddress space. 17 of the 40 MLX kernels fail to compile, including every quantized matmul kernel, somlx.metallibisn't built..build/out/Products/Release/.build.sh,run_benchmark.sh, the profiling scripts and two tests all hard-code.build/arm64-apple-macosx/release/. As a result the metallib is copied to a directory the binary never looks in, and the scripts can't find the binary.Changes
mlx-swiftto fix(metal): build with Xcode 27 / Metal 4.1 (explicit thread on member functions) mlx-swift#16. It backports Fix implicitthreadaddress space qualifier becoming explicit in metal 4.1 ml-explore/mlx#3963 and applies the same fix to the older NAX tile structs. See that PR for the details.build.sh: get the bin dir fromswift build -c release --show-bin-path, and copy the metallib there asmlx.metallib. MLX loads a colocatedmlx.metallibbefore anything else, so the full 128 MB kernel set always takes priority over the 3.8 MB partialdefault.metallibthat SwiftPM puts inmlx-swift_Cmlx.bundle.default.metallibis still copied for mlx-c..build/release/SwiftLM, which is a symlink to the real bin dir on both the old and new SwiftPM layouts.run_benchmark.shnow resolvesMETAL_LIBRARY_PATHthrough the same symlink.scripts/build.shis left alone. It's an older duplicate ofbuild.sh; tell me if it should be removed or brought in line.Verification
./build.shfinishes and writesmlx.metallibanddefault.metallib(128 MB each) to.build/out/Products/Release/.Qwen3.8-27B-4bit, running from.build/release/SwiftLM): all correct, including a code word retrieved from a 7.9K-token prompt; decode 9.0 tok/s. Merge after fix(metal): build with Xcode 27 / Metal 4.1 (explicit thread on member functions) mlx-swift#16.🤖 Generated with Claude Code