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Add Apple CC toolchain setup (#113)
This migrates the Apple CC toolchain from bazel into this repo. This allows this to evolve and be updated without a full bazel udpate. Bazel's built in unix toolchain can still be used to build macOS C++ targets, but this repo handles a wider variety of Apple specific flags and requires you have Xcode installed.
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‎.bazelci/presubmit.yml

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@@ -5,9 +5,19 @@ x_defaults:
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common: &common
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platform: macos
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build_targets:
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- "//..."
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- "//..."
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test_targets:
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- "//..."
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- "//..."
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toolchain_flags: &toolchain_flags
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build_flags:
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- "--apple_crosstool_top=@local_config_apple_cc//:toolchain"
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- "--crosstool_top=@local_config_apple_cc//:toolchain"
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- "--host_crosstool_top=@local_config_apple_cc//:toolchain"
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test_flags:
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- "--apple_crosstool_top=@local_config_apple_cc//:toolchain"
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- "--crosstool_top=@local_config_apple_cc//:toolchain"
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- "--host_crosstool_top=@local_config_apple_cc//:toolchain"
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tasks:
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macos_latest:
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name: "Latest Bazel with Head Deps"
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bazel: latest
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shell_commands:
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# Update the WORKSPACE to use head versions of some deps to ensure nothing
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# has landed on them breaking this project.
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- .bazelci/update_workspace_to_deps_heads.sh
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# Update the WORKSPACE to use head versions of some deps to ensure nothing
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# has landed on them breaking this project.
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- .bazelci/update_workspace_to_deps_heads.sh
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<<: *common
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macos_latest_vendored_toolchain:
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name: "Latest Bazel vendored toolchain"
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bazel: latest
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<<: *common
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<<: *toolchain_flags
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macos_last_green_vendored_toolchain:
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name: "Last Green Bazel vendored toolchain"
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bazel: last_green
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<<: *common
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<<: *toolchain_flags
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buildifier: latest

‎BUILD

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@@ -24,6 +24,8 @@ filegroup(
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testonly = 1,
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srcs = [
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"WORKSPACE",
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"//constraints:for_bazel_tests",
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"//crosstool:for_bazel_tests",
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"//lib:for_bazel_tests",
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"//rules:for_bazel_tests",
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"//tools:for_bazel_tests",

‎MODULE.bazel

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@@ -12,3 +12,8 @@ module(
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bazel_dep(name = "bazel_skylib", version = "1.3.0")
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bazel_dep(name = "platforms", version = "0.0.4")
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bazel_dep(name = "stardoc", version = "0.5.3", dev_dependency = True, repo_name = "io_bazel_stardoc")
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apple_cc_configure = use_extension("//crosstool:setup.bzl", "apple_cc_configure_extension")
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use_repo(apple_cc_configure, "local_config_apple_cc", "local_config_apple_cc_toolchains")
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register_toolchains("@local_config_apple_cc_toolchains//:all")

‎README.md

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@@ -1,14 +1,59 @@
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# Apple Support for [Bazel](https://bazel.build)
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This repository contains helper methods that support building rules that
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target Apple platforms. See [the
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docs](https://github.com/bazelbuild/apple_support/tree/master/doc) for
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how you can use these helpers. Also see
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[rules_apple](https://github.com/bazelbuild/rules_apple) and
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[rules_swift](https://github.com/bazelbuild/rules_swift) for more Apple
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platform rules.
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## Quick setup
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Copy the `WORKSPACE` snippet from [the releases
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page](https://github.com/bazelbuild/apple_support/releases).
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This repository contains the [Apple CC toolchain](#toolchain-setup),
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Apple related [platforms](platforms/BUILD) and
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[constraints](constraints/BUILD) definitions, and small helper functions
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for rules authors targeting Apple platforms.
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If you want to build iOS, tvOS, watchOS, or macOS apps, use
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[`rules_apple`][rules_apple].
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If you want to build Swift use
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[`rules_swift`](https://github.com/bazelbuild/rules_swift).
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See [the documentation](doc) for the helper rules provided by this
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repository.
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## Installation
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Copy the `MODULE.bazel` or `WORKSPACE` snippets from [the releases
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page](https://github.com/bazelbuild/apple_support/releases) into your
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project.
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## Toolchain setup
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The Apple CC toolchain in by this repository provides toolchains for
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building for Apple platforms besides macOS. Since Bazel 7 this toolchain
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is required when targeting those platforms but the toolchain also
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supports Bazel 6.
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To use the Apple CC toolchain, pull this repository into your build and
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add this to your `.bazelrc`:
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```bzl
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build --enable_platform_specific_config
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build:macos --apple_crosstool_top=@local_config_apple_cc//:toolchain
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build:macos --crosstool_top=@local_config_apple_cc//:toolchain
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build:macos --host_crosstool_top=@local_config_apple_cc//:toolchain
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```
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This ensures that all rules provided by [`rules_apple`][rules_apple], as
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well as other rules like `cc_binary`, all use the toolchain provided by
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this repository when building on macOS.
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NOTE: This toolchain requires a full Xcode installation, not just the
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Xcode Command Line Tools. If you only need to build for macOS and don't
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want to require a full Xcode installation in your build, use the builtin
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Unix toolchain provided by Bazel.
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### Incompatible toolchain resolution
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Bazel is currently working on migrating C++ toolchain configuration to a
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new discovery method that no longer uses the `--*crosstool_top` flags.
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If you would like to test this upcoming feature, or need to use this in
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your build for other reasons, you can use this toolchain with
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`--incompatible_enable_cc_toolchain_resolution` as long as you provide a
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`platform_mappings` file. Please file any issues you find as you test
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this work in progress configuration.
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[rules_apple]: https://github.com/bazelbuild/rules_apple

‎constraints/BUILD

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@@ -29,3 +29,11 @@ constraint_value(
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name = "catalyst",
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constraint_setting = ":target_environment",
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)
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# Consumed by bazel tests.
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filegroup(
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name = "for_bazel_tests",
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testonly = True,
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srcs = glob(["**"]),
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visibility = ["//:__pkg__"],
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)

‎crosstool/BUILD

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package(default_visibility = ["//visibility:public"])
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# Files which shouldn't be publicly visible and dependencies of all objc_* or ios_* rules should be excluded.
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exports_files(glob(
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["**"],
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))
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cc_binary(
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name = "wrapped_clang",
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testonly = True,
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srcs = [
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"wrapped_clang.cc",
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],
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)
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# Consumed by bazel tests.
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filegroup(
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name = "for_bazel_tests",
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testonly = True,
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srcs = glob(["**"]),
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visibility = ["//:__pkg__"],
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)

‎crosstool/BUILD.toolchains

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package(default_visibility = ["//visibility:public"])
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# Target constraints for each arch.
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# TODO(apple-rules): Rename osx constraint to macOS.
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OSX_TOOLS_CONSTRAINTS = {
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"armeabi-v7a": ["@platforms//cpu:arm"],
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"darwin_arm64": [
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"@platforms//os:osx",
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"@platforms//cpu:arm64",
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],
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"darwin_arm64e": [
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"@platforms//os:osx",
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"@platforms//cpu:arm64",
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],
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"darwin_x86_64": [
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"@platforms//os:osx",
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"@platforms//cpu:x86_64",
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],
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"ios_arm64": [
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"@platforms//os:ios",
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"@platforms//cpu:arm64",
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"@build_bazel_apple_support//constraints:device",
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],
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"ios_arm64e": [
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"@platforms//os:ios",
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"@platforms//cpu:arm64",
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],
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"ios_armv7": [
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"@platforms//os:ios",
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"@platforms//cpu:armv7",
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],
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"ios_i386": [
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"@platforms//os:ios",
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"@platforms//cpu:i386",
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],
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"ios_x86_64": [
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"@platforms//os:ios",
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"@platforms//cpu:x86_64",
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],
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"ios_sim_arm64": [
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"@platforms//os:ios",
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"@platforms//cpu:arm64",
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"@build_bazel_apple_support//constraints:simulator",
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],
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"tvos_arm64": [
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"@platforms//os:tvos",
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"@platforms//cpu:arm64",
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"@build_bazel_apple_support//constraints:device",
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],
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"tvos_x86_64": [
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"@platforms//os:tvos",
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"@platforms//cpu:x86_64",
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],
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"tvos_sim_arm64": [
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"@platforms//os:tvos",
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"@platforms//cpu:arm64",
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"@build_bazel_apple_support//constraints:simulator",
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],
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"watchos_arm64": [
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"@platforms//os:watchos",
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"@platforms//cpu:arm64",
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],
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"watchos_arm64_32": [
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"@platforms//os:watchos",
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"@platforms//cpu:arm64_32",
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],
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"watchos_armv7k": [
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"@platforms//os:watchos",
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"@platforms//cpu:armv7k",
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],
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"watchos_i386": [
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"@platforms//os:watchos",
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"@platforms//cpu:i386",
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],
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"watchos_x86_64": [
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"@platforms//os:watchos",
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"@platforms//cpu:x86_64",
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],
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}
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OSX_DEVELOPER_PLATFORM_CPUS = [
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"arm64",
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"x86_64",
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]
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[
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toolchain(
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name = "cc-toolchain-" + arch + "-" + cpu,
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exec_compatible_with = [
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# These only execute on macOS.
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"@platforms//os:osx",
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"@platforms//cpu:" + cpu,
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],
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target_compatible_with = OSX_TOOLS_CONSTRAINTS[arch],
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toolchain = "@local_config_apple_cc//:cc-compiler-" + arch,
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toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
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)
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for arch in OSX_TOOLS_CONSTRAINTS.keys()
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for cpu in OSX_DEVELOPER_PLATFORM_CPUS
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]

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