hermetic_cc_toolchain/toolchain/defs.bzl

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
load("@bazel_tools//tools/build_defs/repo:utils.bzl", "read_user_netrc", "use_netrc")
load("@bazel-zig-cc//toolchain/private:defs.bzl", "DEFAULT_INCLUDE_DIRECTORIES", "ZIG_TOOL_PATH", "target_structs")

_fcntl_map = """
GLIBC_2.2.5 {
   fcntl;
};
"""
_fcntl_h = """
#ifdef __ASSEMBLER__
.symver fcntl64, fcntl@GLIBC_2.2.5
#else
__asm__(".symver fcntl64, fcntl@GLIBC_2.2.5");
#endif
"""

# Official recommended version. Should use this when we have a usable release.
URL_FORMAT_RELEASE = "https://ziglang.org/download/{version}/zig-{host_platform}-{version}.tar.xz"

# Caution: nightly releases are purged from ziglang.org after ~90 days. A real
# solution would be to allow the downstream project specify their own mirrors.
# This is explained in
# https://sr.ht/~motiejus/bazel-zig-cc/#alternative-download-urls and is
# awaiting my attention or your contribution.
URL_FORMAT_NIGHTLY = "https://ziglang.org/builds/zig-{host_platform}-{version}.tar.xz"

# Author's mirror that doesn't purge the nightlies so aggressively. I will be
# cleaning those up manually only after the artifacts are not in use for many
# months in bazel-zig-cc. dl.jakstys.lt is a small x86_64 server with an NVMe
# drive sitting in my home closet on a 1GB/s symmetric residential connection,
# which, as of writing, has been quite reliable.
URL_FORMAT_JAKSTYS = "https://dl.jakstys.lt/zig/zig-{host_platform}-{version}.tar.xz"

_VERSION = "0.10.0-dev.2252+a4369918b"

_HOST_PLATFORM_SHA256 = {
    "linux-aarch64": "a88d646f881ae39bde4631e2b48d986a90878f6fadb1a588c8e297a52ac1b606",
    "linux-x86_64": "1d3c3769eba85a4334c93a3cfa35ad0ef914dd8cf9fd502802004c6908f5370c",
    "macos-aarch64": "ab46e7499e5bd7b6d6ff2ac331e1a4aa875a01b270dc40306bc29dbaf216fccf",
    "macos-x86_64": "fb213f996bcab805839e401292c42a92b63cd97deb1631e31bd61f534b7f6b1c",
}

def toolchains(
        version = _VERSION,
        url_formats = [URL_FORMAT_JAKSTYS],
        host_platform_sha256 = _HOST_PLATFORM_SHA256):
    """
        Download zig toolchain and declare bazel toolchains.
        The platforms are not registered automatically, that should be done by
        the user with register_toolchains() in the WORKSPACE file. See README
        for possible choices.
    """
    zig_repository(
        name = "zig_sdk",
        version = version,
        url_formats = url_formats,
        host_platform_sha256 = host_platform_sha256,
        host_platform_include_root = {
            "linux-aarch64": "lib/zig/",
            "linux-x86_64": "lib/",
            "macos-aarch64": "lib/zig/",
            "macos-x86_64": "lib/zig/",
        },
    )

ZIG_TOOL_WRAPPER = """#!/bin/bash
set -e

if [[ -n "$TMPDIR" ]]; then
  _cache_prefix=$TMPDIR
else
  _cache_prefix="$HOME/.cache"
  if [[ "$(uname)" = Darwin ]]; then
    _cache_prefix="$HOME/Library/Caches"
  fi
fi
export ZIG_LOCAL_CACHE_DIR="$_cache_prefix/bazel-zig-cc"
export ZIG_GLOBAL_CACHE_DIR=$ZIG_LOCAL_CACHE_DIR

exec "{zig}" "{zig_tool}" "$@"
"""

_ZIG_TOOLS = [
    "c++",
    "cc",
    "ar",
    "ld.lld",  # ELF
    "ld64.lld",  # Mach-O
    "lld-link",  # COFF
    "wasm-ld",  # WebAssembly
]

def _quote(s):
    return "'" + s.replace("'", "'\\''") + "'"

def _zig_repository_impl(repository_ctx):
    arch = repository_ctx.os.arch
    if arch == "amd64":
        arch = "x86_64"

    os = repository_ctx.os.name.lower()
    if os.startswith("mac os"):
        os = "macos"

    host_platform = "{}-{}".format(os, arch)

    zig_include_root = repository_ctx.attr.host_platform_include_root[host_platform]
    zig_sha256 = repository_ctx.attr.host_platform_sha256[host_platform]
    format_vars = {
        "version": repository_ctx.attr.version,
        "host_platform": host_platform,
    }

    urls = [uf.format(**format_vars) for uf in repository_ctx.attr.url_formats]
    repository_ctx.download_and_extract(
        auth = use_netrc(read_user_netrc(repository_ctx), urls, {}),
        url = urls,
        stripPrefix = "zig-{host_platform}-{version}/".format(**format_vars),
        sha256 = zig_sha256,
    )

    for zig_tool in _ZIG_TOOLS:
        repository_ctx.file(
            ZIG_TOOL_PATH.format(zig_tool = zig_tool),
            ZIG_TOOL_WRAPPER.format(
                zig = str(repository_ctx.path("zig")),
                zig_tool = zig_tool,
            ),
        )

    repository_ctx.file(
        "glibc-hacks/fcntl.map",
        content = _fcntl_map,
    )
    repository_ctx.file(
        "glibc-hacks/glibchack-fcntl.h",
        content = _fcntl_h,
    )

    for dest, src in {
        "platform/BUILD": "//toolchain/platform:BUILD",
        "toolchain/BUILD": "//toolchain/toolchain:BUILD",
        "libc/BUILD": "//toolchain/libc:BUILD",
        "libc_aware/platform/BUILD": "//toolchain/libc_aware/platform:BUILD",
        "libc_aware/toolchain/BUILD": "//toolchain/libc_aware/toolchain:BUILD",
    }.items():
        repository_ctx.symlink(Label(src), dest)

    for dest, src in {
        "BUILD": "//toolchain:BUILD.sdk.bazel",
        "private/BUILD": "//toolchain/private:BUILD.sdk.bazel",
    }.items():
        repository_ctx.template(
            dest,
            Label(src),
            executable = False,
            substitutions = {
                "{absolute_path}": _quote(str(repository_ctx.path(""))),
                "{zig_include_root}": _quote(zig_include_root),
            },
        )

zig_repository = repository_rule(
    attrs = {
        "version": attr.string(),
        "host_platform_sha256": attr.string_dict(),
        "url_formats": attr.string_list(allow_empty = False),
        "host_platform_include_root": attr.string_dict(),
    },
    implementation = _zig_repository_impl,
)

def filegroup(name, **kwargs):
    native.filegroup(name = name, **kwargs)
    return ":" + name

def declare_files(zig_include_root):
    filegroup(name = "empty")
    native.exports_files(["zig"], visibility = ["//visibility:public"])
    filegroup(name = "lib/std", srcs = native.glob(["lib/std/**"]))

    lazy_filegroups = {}

    for target_config in target_structs():
        for d in DEFAULT_INCLUDE_DIRECTORIES + target_config.includes:
            d = zig_include_root + d
            if d not in lazy_filegroups:
                lazy_filegroups[d] = filegroup(name = d, srcs = native.glob([d + "/**"]))