Add macOS arm64 sysroot/lbcxx by mathetake · Pull Request #4656 · envoyproxy/toolshed

mathetake · 2026-06-16T03:41:32Z

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Add repository rules and build scripts for cross-compiling to macOS arm64 from Linux x86_64: - sysroot.bzl: add `macos_sysroot` rule and `setup_macos_sysroot()` for macOS SDK sysroot (headers, frameworks, .tbd stubs) - libcxx_libs.bzl: add `libcxx_libs_darwin` rule and `setup_libcxx_libs_darwin()` for darwin libc++ (dylibs + __config_site) - versions.bzl: add placeholder hashes for macOS sysroot and darwin libcxx - build_macos_sysroot.sh: script to package macOS SDK from Xcode - build_libcxx_darwin.sh: script to build darwin libc++ from LLVM source The macOS SDK sysroot provides system headers and .tbd library stubs. The darwin libcxx provides libc++ dylibs and the __config_site header needed by the LLVM toolchain for cross-compilation. When hashes are empty (tarballs not yet built/uploaded), the rules generate fallback content: the sysroot creates an empty directory, and libcxx_libs generates __config_site from the Linux LLVM version. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Add a `build-macos-sysroot` job to the Bazel CI workflow that runs on `macos-14` and produces two artifacts: 1. `sysroot-macos-arm64.tar.xz` — macOS SDK sysroot extracted from the Xcode installation on the CI runner (headers, frameworks, .tbd stubs) 2. `libcxx-llvm18.1.8-darwin-aarch64.tar.xz` — libc++ built from LLVM source for darwin arm64 (dylibs + __config_site) These artifacts are needed for cross-compiling Envoy (and other C++ projects) from Linux x86_64 to macOS arm64. The Linux sysroots are built by debootstrap on Linux runners; the macOS sysroot requires a macOS runner with Xcode to extract Apple's SDK. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

- Fix shellcheck SC2295: quote expansions inside ${..} in sysroot scripts - Fix shellcheck SC2034: remove unused ARCH variable in libcxx script - Fix cmake error: add libunwind to LLVM_ENABLE_RUNTIMES and set LIBCXXABI_USE_LLVM_UNWINDER=ON (required by libcxxabi) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Some frameworks (e.g., SystemConfiguration) have headers under Versions/A/Headers/ instead of just Headers/. Copy the full framework structure including versioned directories so clang can find all headers. Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com> Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

macOS `cp -a` requires the parent directory to exist. Create it with mkdir -p before copying Headers/Modules directories. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Ruby.framework contains self-referencing symlinks (ruby -> .) that cause infinite recursion during Bazel's glob expansion. Remove these circular symlinks before packaging. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Selectively copying Headers/Modules/tbd from frameworks breaks clang's framework header lookup, which depends on symlinks like: Headers -> Versions/Current/Headers Versions/Current -> A SDK frameworks contain only headers, modules, and .tbd stubs (no large binaries), so copying the entire directory is safe and correct. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Without this, binaries linked against the cross-compiled libc++ fail at runtime with "no LC_RPATH's found" because the dylib install name is @rpath/libc++.1.dylib. macOS ships libc++ at /usr/lib/libc++.1.dylib, so patching the install names makes binaries use the system library. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

mathetake · 2026-06-16T16:25:25Z

sorry will switch to a different way -

Replace the macos-14 runner approach with a fully Linux-based build: Sysroot: Download Apple's CLTools SDK package from their public CDN (swcdn.apple.com, no auth required) and extract on Linux using cerisier/pkgutil. A manifest file selects only the needed files (headers, .tbd stubs, 6 frameworks). Result: ~6MB vs 205MB. Libcxx: Extract __config_site and libc++ dylibs directly from the official LLVM macOS-ARM64 release tarball — no cmake build needed. Patch install names from @rpath/ to /usr/lib/ so binaries use the system libc++ at runtime. Benefits: - No macOS runner needed (cheaper, faster) - Deterministic (pinned URLs + SHA256 checksums) - Minimal sysroot (only files needed for cross-compilation) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Apple's CDN may reject requests without a browser user-agent. Also fix stale comment referencing macos-14 runner. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

LLVM 18.x uses "clang+llvm-VER-arm64-apple-macosNN" naming convention, not "LLVM-VER-macOS-ARM64" (which is the newer format from LLVM 20+). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

The macOS LLVM tarball's llvm-install-name-tool is a Mach-O binary that can't run on Linux. Use the Linux distro's llvm-install-name-tool instead — it can edit Mach-O files cross-platform. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

The system llvm package doesn't include llvm-install-name-tool. Extract it from the Linux LLVM 18.1.8 release instead. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

llvm-install-name-tool is a symlink to llvm-objcopy that changes behavior based on argv[0]. Extract llvm-objcopy and create the symlink. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

The pre-built LLVM 18 binaries need libtinfo.so.5 which isn't on Ubuntu 24.04. Use the system llvm-18 package instead. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

These cmake/Xcode-based scripts are superseded by the CI job that extracts pre-built artifacts from Apple's CDN and LLVM releases. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

phlax · 2026-06-16T21:39:07Z

ci/docker error is unrelated annoyance

phlax · 2026-06-16T21:41:12Z

+    # Darwin libc++ cross-compilation libraries (built from LLVM source for macOS arm64)
+    # Contains include/__config_site and lib/libc++.dylib, lib/libc++abi.dylib
+    "libcxx_libs_darwin_sha256": {
+        "aarch64": "",  # TODO: populate after building and uploading tarball


we might need to hook this into the ci bazel/prepare step

d602445 🤞

Hook the macOS cross-compilation artifact hashes into the bazel release prepare step in _release.yml. When a bins release is created, the jq filter now also updates macos_sysroot_sha256 and libcxx_libs_darwin_sha256 in versions.bzl from the release asset checksums. Handles both initial population (empty string → hash) and updates (old hash → new hash). Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com> Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

mathetake · 2026-06-16T22:39:05Z

docker 🤷

mathetake requested a review from phlax June 16, 2026 03:44

mathetake and others added 3 commits June 16, 2026 15:00

mathetake force-pushed the tyoneda/darwin-cross-compilation branch from 043c3fe to fa34f54 Compare June 16, 2026 15:00

mathetake marked this pull request as ready for review June 16, 2026 15:08

mathetake and others added 5 commits June 16, 2026 15:13

mathetake marked this pull request as draft June 16, 2026 16:25

mathetake and others added 8 commits June 16, 2026 16:27

fix: yamllint line-length for Apple CDN URL

95372b2

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

mathetake marked this pull request as ready for review June 16, 2026 20:59

phlax reviewed Jun 16, 2026

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Comment thread .github/workflows/_bazel.yml Outdated

fix: use YAML block scalar for long URL per review

0da1bd9

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

mathetake enabled auto-merge (squash) June 16, 2026 21:09

phlax reviewed Jun 16, 2026

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Comment thread .github/workflows/_bazel.yml Outdated

mathetake and others added 2 commits June 16, 2026 21:33

fix: rename job/steps to reflect extract, not build

406c810

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com> Signed-off-by: Takeshi Yoneda <tyoneda@netflix.com>

mathetake force-pushed the tyoneda/darwin-cross-compilation branch from 6eabf64 to 406c810 Compare June 16, 2026 21:37

phlax reviewed Jun 16, 2026

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mathetake changed the title ~~sysroot/compile: add macOS arm64 cross-compilation support~~ Add macOS arm64 sysroot/lbcxx Jun 16, 2026

mathetake disabled auto-merge June 16, 2026 21:49

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Add macOS arm64 sysroot/lbcxx#4656

Add macOS arm64 sysroot/lbcxx#4656
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