unregister default toolchains; update README
Motiejus Jakštys
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@ -9,6 +9,9 @@ environment:
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tasks:
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- setup: |
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sudo apt-get purge gcc -y && sudo apt-get autoremove -y
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- test_list_toolchains: |
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cd bazel-zig-cc; . .envrc; echo "Available toolchains:"
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bazel query @zig_sdk//... | sed -En '/.*_toolchain$/ s/.*:(.*)_toolchain$/\1/p'
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- test_default: |
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cd bazel-zig-cc; . .envrc; ./build-and-file \
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//test:hello | \
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89
README.md
89
README.md
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@ -2,17 +2,12 @@
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# Bazel zig cc toolchain
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This is an early stage zig-cc toolchain that can cross-compile C/C++ programs
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(including cgo) to these os/archs:
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- amd64-linux-gnu.2.19
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- amd64-linux-musl
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- arm64-linux-gnu.2.28
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- arm64-linux-musl
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- amd64-macos
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- arm64-macos
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... and more.
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This is a C/C++ toolchain that can (cross-)compile C/C++ programs. It contains
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clang-12, musl, glibc (versions 2-2.33, selectable), all in a ~40MB package.
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Read
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[here](https://andrewkelley.me/post/zig-cc-powerful-drop-in-replacement-gcc-clang.html)
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about zig-cc; the rest of the README will present how to use this toolchain
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from Bazel.
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# Usage
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@ -30,11 +25,34 @@ http_archive(
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load("@bazel-zig-cc//toolchain:defs.bzl", zig_register_toolchains = "register_toolchains")
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zig_register_toolchains()
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zig_register_toolchains(["x86_64-linux-gnu.2.28", "x86_64-macos-gnu"])
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```
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This will register the "default" toolchains. Look into `register_toolchains` on
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which parameters it accepts.
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The snippet above will download the zig toolchain and register it for the
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following platforms:
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- `x86_64-linux-gnu.2.28` for `["@platforms//os:linux", "@platforms//cpu:x86_64"]`.
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- `x86_64-macos-gnu` for `["@platforms//os:macos", "@platforms//cpu:x86_64"]`.
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Note that both Go and Bazel naming schemes are accepted. For convenience with
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Go, the following Go-style toolchain aliases are created:
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|Bazel (zig) name |Go name|
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--- | ---
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|`x86_64`|`amd64`|
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|`aarch64`|`arm64`|
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|`macos`|`darwin`|
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For example, the toolchain `linux_amd64_gnu is aliased to
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`x86_64-linux-gnu.2.28`. .2.28`.
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To find out which toolchains can be registered or used, run this:
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```
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$ bazel query @zig_sdk//... | sed -En '/.*_toolchain$/ s/.*:(.*)_toolchain$/\1/p'
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```
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This is still work in progress; please read [#Known Issues] before using.
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# Testing
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@ -81,11 +99,46 @@ how CI does it.
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# Known Issues
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- [ziglang/zig #9485 glibc 2.27 or older: fcntl64 not found, but zig's glibc headers refer it](https://github.com/ziglang/zig/issues/9485)
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- [ziglang/zig #9431 FileNotFound when compiling macos](https://github.com/ziglang/zig/issues/9431)
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- [rules/go #2894 Per-arch_target linker flags](https://github.com/bazelbuild/rules_go/issues/2894)
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## Parallel `zig c++` invocations may fail
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Closed issues:
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Task: [ziglang/zig #9431 FileNotFound when compiling macos](https://github.com/ziglang/zig/issues/9431)
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Background: there is a race when calling `zig c++`, which Bazel does a lot.
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This may fail compilation. Yours truly only reproduced it on macos with a cold
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cache. Based on that, a workaround in the toolchain exists, named
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`speed_first_safety_later`. The possible values are `auto` (default), `yes`,
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`no`.
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## glibc 2.27 or older
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Task: [ziglang/zig #9485 glibc 2.27 or older: fcntl64 not found, but zig's glibc headers refer it](https://github.com/ziglang/zig/issues/9485)
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Background: when glibc 2.27 or older is selected, it may miss `fcntl64`. A
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workaround is applied for `x86_64`, but not for aarch64. The same workaround
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may apply to aarch64, but the author didn't find a need to test or ensure it
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(yet).
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## cgo for darwin (macos)
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Task: [rules/go #2894 Per-arch_target linker flags](https://github.com/bazelbuild/rules_go/issues/2894)
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Background: this toolchain needs an extra step to be used for Darwin (macos)
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targets. Specifically, one needs to add `gc_linkopts` for every `go_binary`:
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```
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go_binary(
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<...>
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gc_linkopts = select({
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"@platforms//os:macos": ["-s", "-w", "-buildmode=pie"],
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"//conditions:default": [],
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}),
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)
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```
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Until the linked task is resolved, this needs to be done for every `go_binary`
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that is meant to be compiled to Darwin.
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# Closed issues
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- [ziglang/zig #9139 zig c++ hanging when compiling in parallel](https://github.com/ziglang/zig/issues/9139) (CLOSED)
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- [golang/go #46644 cmd/link: with CC=zig: SIGSERV when cross-compiling to darwin/amd64](https://github.com/golang/go/issues/46644) (CLOSED)
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@ -53,4 +53,11 @@ load(
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zig_register_toolchains = "register_toolchains",
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)
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zig_register_toolchains(speed_first_safety_later="auto")
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_REGISTER_TOOLCHAINS = [
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"linux_arm64_gnu.2.28",
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"linux_amd64_gnu.2.19",
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"darwin_amd64",
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"darwin_arm64",
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]
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zig_register_toolchains(register = _REGISTER_TOOLCHAINS)
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@ -56,13 +56,6 @@ _GLIBCS = [
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"2.33",
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]
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DEFAULT_TOOLCHAINS = [
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"linux_arm64_gnu.2.28", # There is a problem with fcntl on arm64, this is WIP
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"linux_amd64_gnu.2.19", # Debian Jessie amd64
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"darwin_amd64",
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"darwin_arm64",
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]
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def _target_darwin(gocpu, zigcpu):
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return struct(
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gotarget = "darwin_{}".format(gocpu),
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@ -146,8 +139,16 @@ def _target_linux_musl(gocpu, zigcpu):
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)
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def register_toolchains(
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register = DEFAULT_TOOLCHAINS,
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register = [],
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speed_first_safety_later = "auto"):
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"""
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Download zig toolchain and register some.
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@param register registers the given toolchains to the system using
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native.register_toolchains(). See README for possible choices.
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@param speed_first_safety_later is a workaround for
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https://github.com/ziglang/zig/issues/9431
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"""
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zig_repository(
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name = "zig_sdk",
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# Pre-release:
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@ -311,10 +312,6 @@ def zig_build_macro(absolute_path, zig_include_root):
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for target_config in _target_structs():
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gotarget = target_config.gotarget
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zigtarget = target_config.zigtarget
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native.platform(
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name = gotarget,
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constraint_values = target_config.constraint_values,
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)
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cxx_builtin_include_directories = []
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for d in DEFAULT_INCLUDE_DIRECTORIES + target_config.includes:
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@ -341,7 +338,7 @@ def zig_build_macro(absolute_path, zig_include_root):
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copts = copts + ["-include", absolute_path + "/" + incl]
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zig_cc_toolchain_config(
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name = zigtarget + "_cc_toolchain_config",
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name = zigtarget + "_toolchain_cc_config",
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target = zigtarget,
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tool_paths = absolute_tool_paths,
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cxx_builtin_include_directories = cxx_builtin_include_directories,
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@ -356,9 +353,9 @@ def zig_build_macro(absolute_path, zig_include_root):
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)
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native.cc_toolchain(
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name = zigtarget + "_cc_toolchain",
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name = zigtarget + "_toolchain_cc",
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toolchain_identifier = zigtarget + "-toolchain",
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toolchain_config = ":%s_cc_toolchain_config" % zigtarget,
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toolchain_config = ":%s_toolchain_cc_config" % zigtarget,
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all_files = ":zig",
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ar_files = ":zig",
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compiler_files = ":zig",
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@ -375,7 +372,7 @@ def zig_build_macro(absolute_path, zig_include_root):
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name = gotarget + "_toolchain",
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exec_compatible_with = None,
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target_compatible_with = target_config.constraint_values,
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toolchain = ":%s_cc_toolchain" % zigtarget,
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toolchain = ":%s_toolchain_cc" % zigtarget,
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toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
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)
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@ -384,6 +381,6 @@ def zig_build_macro(absolute_path, zig_include_root):
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name = zigtarget + "_toolchain",
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exec_compatible_with = None,
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target_compatible_with = target_config.constraint_values,
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toolchain = ":%s_cc_toolchain" % zigtarget,
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toolchain = ":%s_toolchain_cc" % zigtarget,
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toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
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)
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