spaCy for Windows ARM64: Build Tools & Pre-compiled Wheels

This repository contains tools and instructions to successfully compile spaCy (and its dependencies like srsly, blis, thinc) on Windows on ARM64 devices (Surface Pro X, Surface Laptop 7, Snapdragon Dev Kits, etc.).

🛑 The Problem

Building spaCy from source via pip on Windows ARM64 often fails with:

• Compiler Crashes: error: command 'cl.exe' failed: None (The native MSVC compiler is unstable in some environments).
• Linker Errors: lld-link: error: could not open 'libcmt.lib' (Library paths are not automatically found).
• Narrowing Errors: error: non-constant-expression cannot be narrowed (If switching to Clang without specific flags).

✅ The Solution

This repository provides a "Masquerade Script" (build_spacy_arm64.bat) that:

1. Activates the correct Visual Studio ARM64 environment.
2. Shims the compiler: It forces Python to use clang-cl.exe (which is stable) by disguising it as cl.exe.
3. Auto-Locates Libraries: It hunts your drive for the correct ARM64 versions of msvcrt.lib, kernel32.lib, and ucrt.lib and forces the linker to use them.
4. Fixes Compilation: Injects flags (-Wno-c++11-narrowing) to bypass strict Clang errors.

🚀 Quick Start (Use the Wheel)

If you just want to install spaCy without building it, download the .whl file from the [Releases/Dist folder] and run:

pip install spacy-3.x.x-cp311-cp311-win_arm64.whl

🛠️ How to Build from Source

If you need to build it yourself (e.g., for a different python version), follow these steps.

1. Prerequisites

   • Install Visual Studio Build Tools 2022. In the "Individual Components" tab, ensure these are checked:

   • MSVC v143 - VS 2022 C++ ARM64/ARM64EC build tools

   • C++ Clang Compiler for Windows

   • Windows 11 SDK (10.0.22621.0) (Critical for libcmt.lib)

   • C++ ATL for v143 build tools (ARM64)

2. Setup

   • Clone this repo.

   • Download the spaCy source code.

   • Copy "build_scripts/force_build_arm64.bat" into the root of the spaCy source folder.

3. Run the Builder

   Right-click -> "force_build_arm64.bat" and select Run as Administrator.

   The script will:

   • Detect your Python installation automatically.

   • Create a temp shim folder (C:\cls_shim).

   • Install build dependencies (cython, numpy).

   • Compile the project using the Clang shim.

   • Output the final .whl file in the dist/ folder.