Force Bazel to use different minimum macos version

[os12345678]

I am trying to bazel build @llvm-project//mlir/...:all but am getting errors with the minimum macos version.

external/llvm-project/llvm/utils/TableGen/DFAEmitter.cpp:367:18: error: 'get<unsigned int, llvm::Record *, unsigned int, std::string>' is unavailable: introduced in macOS 10.13 OS << std::get<unsigned>(SingleAction); ^

/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/v1/variant:1544:22: note: 'get<unsigned int, llvm::Record *, unsigned int, std::string>' has been explicitly marked unavailable here constexpr const _Tp& get(const variant<_Types...>& __v) {

I have added --macos_minimum_os=10.13 in .bazelrc but it seems to get ignored - building with verbose_failure flag shows '-mmacosx-version-min=10.11.

sw_vers ProductName: macOS ProductVersion: 13.2.1 BuildVersion: 22D68
clang --version Apple clang version 14.0.0 (clang-1400.0.29.202) Target: arm64-apple-darwin22.3.0 Thread model: posix InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Any help is appreciated, thanks!

[j2kun]

I don't have a mac machine to test on, but I think that flag may be for when you're building applications for Mac systems, not necessarily which C++ toolchain is used.

I see this in bazel upstream: https://github.com/bazelbuild/bazel/blob/28898a91543cb9388fae4231ccbebbba65177d71/src/main/starlark/builtins_bzl/common/xcode/providers.bzl#L177-L193

Which suggests to me you should be setting some macos_sdk_version: https://bazel.build/reference/command-line-reference#flag--macos_sdk_version

Could you try that and let me know if it works? Please send a PR to add that to .bazelrc if you get it working and have the time.

[j2kun]

I'm afraid you may need to update your xcode version, because it looks like bazel detects the xcode version automatically here.

[Stevengre]

Thank you very much for this helpful tutorial! In my macbook air M2, this command cannot be ommitted in .bazelrc:common --host_cxxopt='-std=c++17'. However, the environment setup seems can be skiped. I just check this and I don't know why. I hope this information can be helpful.