feat: build and test on native arm64 runners

.github/workflows/build.yaml

@@ -18,7 +18,7 @@ jobs:
   build-sdist:
     name: Source distribution
     if: startsWith(github.ref, 'refs/tags/v')
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     steps:
       - uses: actions/checkout@v7
         with:
@@ -48,15 +48,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-latest]
+        os: [ubuntu-26.04, ubuntu-26.04-arm, windows-2025, windows-11-arm, macos-26]
 
     steps:
-      - name: Set up QEMU
-        if: runner.os == 'Linux'
-        uses: docker/setup-qemu-action@v4
-        with:
-          platforms: arm64
-
       - uses: actions/checkout@v7
         with:
           submodules: recursive
@@ -65,15 +59,15 @@ jobs:
 
       - uses: actions/upload-artifact@v7
         with:
-          name: wheels-${{ runner.os }}
+          name: wheels-${{ matrix.os }}
           path: wheelhouse/*.whl
           if-no-files-found: error
 
   publish:
     name: Publish to PyPI
     if: startsWith(github.ref, 'refs/tags/v')
     needs: [build-sdist, build-wheels]
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     environment:
       name: pypi
       url: https://pypi.org/project/cchardet/

.github/workflows/test.yml

@@ -16,7 +16,7 @@ concurrency:
 jobs:
   native-safety:
     name: Native ASan / UBSan
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     steps:
       - uses: actions/checkout@v7
         with:
@@ -40,7 +40,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-latest]
+        os: [ubuntu-26.04, ubuntu-26.04-arm, windows-2025, windows-11-arm, macos-26]
         python-version: ["3.11", "3.12", "3.13", "3.14", "3.14t", "3.15", "3.15t"]
 
     steps:
@@ -51,25 +51,42 @@ jobs:
       - uses: astral-sh/setup-uv@c18668ad3cf93ea998bef934396af7bb5c839dc7 # v10.2.0
         with:
           version: latest-known
-          python-version: ${{ matrix.python-version }}
+          # On Windows ARM64, uv picks an emulated x86-64 interpreter unless the
+          # request names the architecture.
+          python-version: ${{ matrix.os == 'windows-11-arm' && format('cpython-{0}-windows-aarch64-none', matrix.python-version) || matrix.python-version }}
 
       - name: Install locked dependencies
         run: uv sync --locked
 
+      - name: Check interpreter architecture
+        shell: bash
+        run: |
+          uv run --no-sync python - <<'EOF'
+          import os
+          import platform
+          import sysconfig
+
+          plat = sysconfig.get_platform()
+          # A universal2 build covers both macOS architectures, so check the running process.
+          arch = platform.machine() if plat.endswith("universal2") else plat
+          print(plat, arch)
+          assert ("arm64" in arch or "aarch64" in arch) == (os.environ["RUNNER_ARCH"] == "ARM64")
+          EOF
+
       - name: Lint
-        if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.14'
+        if: matrix.os == 'ubuntu-26.04' && matrix.python-version == '3.14'
         run: uv run ruff check
 
       - name: Type check
-        if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.14'
+        if: matrix.os == 'ubuntu-26.04' && matrix.python-version == '3.14'
         run: uv run mypy
 
       - name: Test
         run: uv run pytest
 
   package:
     name: Verify distributions
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-26.04
     steps:
       - uses: actions/checkout@v7
         with:

CHANGES.md

@@ -4,6 +4,10 @@
 
 - Support Python 3.15, including the free-threaded CPython 3.15 build, with
   tests and wheels for Linux, macOS, and Windows
+- Publish Windows ARM64 wheels, and build Linux aarch64 wheels on native arm64
+  runners instead of under QEMU emulation
+- Test every supported Python version on arm64 Linux and Windows in addition to
+  x86-64
 
 ## 2.3.0 (2026-09-16)
 

README.md

@@ -12,8 +12,8 @@ cChardet is a high-speed universal character encoding detector built on the
 ## Python support
 
 cChardet supports CPython 3.11 through 3.15, including the free-threaded
-CPython 3.14 and 3.15 builds. Each version is tested on Linux, macOS, and
-Windows.
+CPython 3.14 and 3.15 builds. Each version is tested on Linux and Windows on
+both x86-64 and arm64, and on macOS on Apple silicon.
 
 ## Development
 
@@ -239,6 +239,6 @@ See **COPYING** file.
 
 ## Support Platforms
 
-- Windows x86, x86_64
+- Windows x86, x86_64, ARM64
 - Linux x86_64, aarch64
 - macOS x86_64, arm64

pyproject.toml

@@ -73,8 +73,5 @@ archs = "auto"
 test-command = "python tools/wheel_smoke.py"
 test-sources = ["tools/wheel_smoke.py"]
 
-[tool.cibuildwheel.linux]
-archs = ["auto", "aarch64"]
-
 [tool.cibuildwheel.macos]
 archs = ["x86_64", "arm64"]