feat: bootstrap bun toolchain skeleton and smoke test

bun/BUILD.bazel

@@ -0,0 +1,103 @@
+load(":toolchain.bzl", "bun_toolchain")
+
+toolchain_type(name = "toolchain_type")
+
+bun_toolchain(
+    name = "linux_x64_toolchain_impl",
+    bun = "@bun_linux_x64//:bun",
+    version = "1.1.38",
+)
+
+bun_toolchain(
+    name = "linux_aarch64_toolchain_impl",
+    bun = "@bun_linux_aarch64//:bun",
+    version = "1.1.38",
+)
+
+bun_toolchain(
+    name = "darwin_x64_toolchain_impl",
+    bun = "@bun_darwin_x64//:bun",
+    version = "1.1.38",
+)
+
+bun_toolchain(
+    name = "darwin_aarch64_toolchain_impl",
+    bun = "@bun_darwin_aarch64//:bun",
+    version = "1.1.38",
+)
+
+bun_toolchain(
+    name = "windows_x64_toolchain_impl",
+    bun = "@bun_windows_x64//:bun",
+    version = "1.1.38",
+)
+
+toolchain(
+    name = "linux_x64_toolchain",
+    exec_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    toolchain = ":linux_x64_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)
+
+toolchain(
+    name = "linux_aarch64_toolchain",
+    exec_compatible_with = [
+        "@platforms//cpu:arm64",
+        "@platforms//os:linux",
+    ],
+    target_compatible_with = [
+        "@platforms//cpu:arm64",
+        "@platforms//os:linux",
+    ],
+    toolchain = ":linux_aarch64_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)
+
+toolchain(
+    name = "darwin_x64_toolchain",
+    exec_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:macos",
+    ],
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:macos",
+    ],
+    toolchain = ":darwin_x64_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)
+
+toolchain(
+    name = "darwin_aarch64_toolchain",
+    exec_compatible_with = [
+        "@platforms//cpu:arm64",
+        "@platforms//os:macos",
+    ],
+    target_compatible_with = [
+        "@platforms//cpu:arm64",
+        "@platforms//os:macos",
+    ],
+    toolchain = ":darwin_aarch64_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)
+
+toolchain(
+    name = "windows_x64_toolchain",
+    exec_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:windows",
+    ],
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:windows",
+    ],
+    toolchain = ":windows_x64_toolchain_impl",
+    toolchain_type = ":toolchain_type",
+)

bun/defs.bzl

@@ -0,0 +1,9 @@
+load(":repositories.bzl", "bun_register_toolchains", "bun_repositories")
+load(":toolchain.bzl", "BunToolchainInfo", "bun_toolchain")
+
+__all__ = [
+    "BunToolchainInfo",
+    "bun_register_toolchains",
+    "bun_repositories",
+    "bun_toolchain",
+]

bun/repositories.bzl

@@ -0,0 +1,73 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+_BUN_VERSION = "1.1.38"
+
+_BUN_ARCHIVES = {
+    "bun_linux_x64": {
+        "sha256": "a61da5357e28d4977fccd4851fed62ff4da3ea33853005c7dd93dac80bc53932",
+        "asset": "bun-linux-x64.zip",
+        "binary": "bun-linux-x64/bun",
+    },
+    "bun_linux_aarch64": {
+        "sha256": "3b08fd0b31f745509e1fed9c690c80d1a32ef2b3c8d059583f643f696639bd21",
+        "asset": "bun-linux-aarch64.zip",
+        "binary": "bun-linux-aarch64/bun",
+    },
+    "bun_darwin_x64": {
+        "sha256": "4e9814c9b2e64f9166ed8fc2a48f905a2195ea599b7ceda7ac821688520428a5",
+        "asset": "bun-darwin-x64.zip",
+        "binary": "bun-darwin-x64/bun",
+    },
+    "bun_darwin_aarch64": {
+        "sha256": "bbc6fb0e7bb99e7e95001ba05105cf09d0b79c06941d9f6ee3d0b34dc1541590",
+        "asset": "bun-darwin-aarch64.zip",
+        "binary": "bun-darwin-aarch64/bun",
+    },
+    "bun_windows_x64": {
+        "sha256": "52d6c588237c5a1071839dc20dc96f19ca9f8021b7757fa096d22927b0a44a8b",
+        "asset": "bun-windows-x64.zip",
+        "binary": "bun-windows-x64/bun.exe",
+    },
+}
+
+
+def _declare_bun_repo(name, asset, sha256, binary, version):
+    if native.existing_rule(name):
+        return
+
+    http_archive(
+        name = name,
+        urls = ["https://github.com/oven-sh/bun/releases/download/bun-v{}/{}".format(version, asset)],
+        sha256 = sha256,
+        build_file_content = """
+exports_files(["{binary}"])
+
+filegroup(
+    name = "bun",
+    srcs = ["{binary}"],
+    visibility = ["//visibility:public"],
+)
+""".format(binary = binary),
+    )
+
+
+def bun_repositories(version = _BUN_VERSION):
+    for name, metadata in _BUN_ARCHIVES.items():
+        _declare_bun_repo(
+            name = name,
+            asset = metadata["asset"],
+            sha256 = metadata["sha256"],
+            binary = metadata["binary"],
+            version = version,
+        )
+
+
+def bun_register_toolchains(version = _BUN_VERSION):
+    bun_repositories(version = version)
+    native.register_toolchains(
+        "//bun:darwin_aarch64_toolchain",
+        "//bun:darwin_x64_toolchain",
+        "//bun:linux_aarch64_toolchain",
+        "//bun:linux_x64_toolchain",
+        "//bun:windows_x64_toolchain",
+    )

bun/toolchain.bzl

@@ -0,0 +1,21 @@
+BunToolchainInfo = provider(fields = ["bun_bin", "version"])
+
+
+def _bun_toolchain_impl(ctx):
+    return [
+        platform_common.ToolchainInfo(
+            bun = BunToolchainInfo(
+                bun_bin = ctx.executable.bun,
+                version = ctx.attr.version,
+            ),
+        ),
+    ]
+
+
+bun_toolchain = rule(
+    implementation = _bun_toolchain_impl,
+    attrs = {
+        "bun": attr.label(allow_single_file = True, executable = True, cfg = "exec"),
+        "version": attr.string(mandatory = True),
+    },
+)