build: Try Zig CC for x86_64 Linux

Author: varungandhi-src

.bazelrc

@@ -59,3 +59,5 @@ build:dev --copt="-Og" # For testing against large projects locally
 
 build:release --copt="-O2"
 build:release --config=stacktraces
+# Zig uses UBSan by default
+build:release --copt="-fno-sanitize=undefined"

WORKSPACE

@@ -4,6 +4,17 @@ load("//:fetch_deps.bzl", "fetch_direct_dependencies")
 
 fetch_direct_dependencies()
 
+load("@bazel-zig-cc//toolchain:defs.bzl", zig_toolchains = "toolchains")
+
+zig_toolchains()
+
+# Register the Zig toolchain before the grailbio one
+# so that the Zig one is preferred on Linux.
+register_toolchains(
+    "@zig_sdk//toolchain:linux_amd64_gnu.2.19",
+    "@zig_sdk//toolchain:linux_arm64_gnu.2.28",
+)
+
 # Setup the toolchain before setting up other dependencies
 load("@com_grail_bazel_toolchain//toolchain:deps.bzl", "bazel_toolchain_dependencies")
 
@@ -14,10 +25,11 @@ load("//:setup_llvm.bzl", "setup_llvm_toolchain")
 setup_llvm_toolchain(name = "llvm_toolchain")
 
 load("@llvm_toolchain//:toolchains.bzl", "llvm_register_toolchains")
-load("@rules_python//python:repositories.bzl", "py_repositories", "python_register_toolchains")
 
 llvm_register_toolchains()
 
+load("@rules_python//python:repositories.bzl", "py_repositories", "python_register_toolchains")
+
 python_register_toolchains(
     name = "python_3_10",
     # Remove this once agents stop running tests as root

fetch_deps.bzl

@@ -16,6 +16,7 @@ _SCIP_COMMIT = "aa0e511dcfefbacc3b96dcc2fe2abd9894416b1e"
 # in the types for which we implement hashing and comparison in
 # indexer/ScipExtras.{h,cc}
 
+_BAZEL_ZIG_CC_VERSION = "v1.0.1"
 _DOCTEST_VERSION = "2.4.9"
 _DTL_VERSION = "1.20"
 _RULES_PYTHON_VERSION = "0.18.1"
@@ -46,6 +47,18 @@ def fetch_direct_dependencies():
         ],
     )
 
+    http_archive(
+        # The repo hard-codes this name in internal functions,
+        # so use kebab-case instead of camel case.
+        name = "bazel-zig-cc",
+        sha256 = "e9f82bfb74b3df5ca0e67f4d4989e7f1f7ce3386c295fd7fda881ab91f83e509",
+        strip_prefix = "bazel-zig-cc-{}".format(_BAZEL_ZIG_CC_VERSION),
+        urls = [
+            "https://mirror.bazel.build/github.com/uber/bazel-zig-cc/releases/download/{0}/{0}.tar.gz".format(_BAZEL_ZIG_CC_VERSION),
+            "https://github.com/uber/bazel-zig-cc/releases/download/{0}/{0}.tar.gz".format(_BAZEL_ZIG_CC_VERSION),
+        ],
+    )
+
     http_archive(
         name = "com_github_nelhage_rules_boost",
         sha256 = "dc9140b868de82ae46dd44da73a7d9749b680b1e7d63b0912288c2de2cabcb1d",

setup_llvm.bzl

@@ -4,6 +4,9 @@ def setup_llvm_toolchain(name):
     # NOTE: The ASan build uses paths which involve the version.
     # Keep the version list in sync with settings.bzl
     mapping = {
+        # Even though we're using zig cc on Linux, keep these
+        # in to keep clang-format working in CI until we figure
+        # out a more lightweight solution.
         "linux-aarch64": {"version": "15.0.6", "triple": "aarch64-linux-gnu", "sha256": "8ca4d68cf103da8331ca3f35fe23d940c1b78fb7f0d4763c1c059e352f5d1bec"},
         "linux-x86_64": {"version": "15.0.6", "triple": "x86_64-linux-gnu-ubuntu-18.04", "sha256": "38bc7f5563642e73e69ac5626724e206d6d539fbef653541b34cae0ba9c3f036"},
         "darwin-arm64": {"version": "15.0.6", "triple": "arm64-apple-darwin21.0", "sha256": "32bc7b8eee3d98f72dd4e5651e6da990274ee2d28c5c19a7d8237eb817ce8d91"},