[Build] Fix CPU extension build on macOS ARM64#41538
[Build] Fix CPU extension build on macOS ARM64#41538guru-meesho wants to merge 1 commit intovllm-project:mainfrom
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Two issues prevent building vLLM's CPU backend on ARM with Clang: 1. C++ standard set to 17, but csrc/cpu/cpu_attn_vec.hpp uses C++20 structured bindings captured in lambdas. GCC permits this as an extension in C++17 mode, but Clang rejects it. Bump to C++20. 2. FP32Vec16(const BF16Vec32&, int) constructor exists in x86 types but is missing from cpu_types_arm.hpp, causing a compilation error in load_b_pair_vec() for FP8 attention paths. Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
guru-meesho
requested review from
LucasWilkinson,
bigPYJ1151 and
tlrmchlsmth
as code owners
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Code Review
This pull request updates the C++ standard from C++17 to C++20 in the CMake configuration files and introduces a new constructor for the FP32Vec16 struct in the ARM CPU types to support conversions from BF16Vec32. I have no feedback to provide.
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@LucasWilkinson can you please review this PR. Was considering contributing to the codebase and as first step needed to build the code base locally but faced issue while compiling the code via clang. Checked the codebase and it seems even though c++ 20 features such as lambda is being used the cmake refers to c++ 17 leading to issues while compilation using clang due to stricter rule adherence while the same compilation passes when using gcc. |
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Thanks @guru-meesho But the issue should be resolved by #41387 |
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Summary
Fixes #41537
FP32Vec16(const BF16Vec32&, int)constructor tocpu_types_arm.hpp— this constructor exists incpu_types_x86.hppbut was never ported to the ARM types header, causing a compilation error inload_b_pair_vec()for FP8 attention pathsTest plan
uv pip install --editable . --torch-backend=auto🤖 Generated with Claude Code