Vendor dependencies

Let's see how I like this workflow.

vendor/cxx/tools/buck/prelude/apple/apple_toolchain.bzl

@@ -0,0 +1,43 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under both the MIT license found in the
+# LICENSE-MIT file in the root directory of this source tree and the Apache
+# License, Version 2.0 found in the LICENSE-APACHE file in the root directory
+# of this source tree.
+
+load("@prelude//apple:apple_toolchain_types.bzl", "AppleToolchainInfo")
+load("@prelude//apple:swift_toolchain_types.bzl", "SwiftToolchainInfo")
+load("@prelude//cxx:cxx_toolchain_types.bzl", "CxxPlatformInfo", "CxxToolchainInfo")
+
+def apple_toolchain_impl(ctx: "context") -> ["provider"]:
+    sdk_path = ctx.attrs._internal_sdk_path or ctx.attrs.sdk_path
+    platform_path = ctx.attrs._internal_platform_path or ctx.attrs.platform_path
+    return [
+        DefaultInfo(),
+        AppleToolchainInfo(
+            actool = ctx.attrs.actool[RunInfo],
+            ibtool = ctx.attrs.ibtool[RunInfo],
+            dsymutil = ctx.attrs.dsymutil[RunInfo],
+            dwarfdump = ctx.attrs.dwarfdump[RunInfo] if ctx.attrs.dwarfdump else None,
+            lipo = ctx.attrs.lipo[RunInfo],
+            cxx_platform_info = ctx.attrs.cxx_toolchain[CxxPlatformInfo],
+            cxx_toolchain_info = ctx.attrs.cxx_toolchain[CxxToolchainInfo],
+            codesign = ctx.attrs.codesign[RunInfo],
+            codesign_allocate = ctx.attrs.codesign_allocate[RunInfo],
+            codesign_identities_command = ctx.attrs.codesign_identities_command[RunInfo] if ctx.attrs.codesign_identities_command else None,
+            compile_resources_locally = ctx.attrs.compile_resources_locally,
+            libtool = ctx.attrs.libtool[RunInfo],
+            momc = ctx.attrs.momc[RunInfo],
+            min_version = ctx.attrs.min_version,
+            xctest = ctx.attrs.xctest[RunInfo],
+            platform_path = platform_path,
+            sdk_name = ctx.attrs.sdk_name,
+            sdk_path = sdk_path,
+            sdk_version = ctx.attrs.version,
+            sdk_build_version = ctx.attrs.build_version,
+            swift_toolchain_info = ctx.attrs.swift_toolchain[SwiftToolchainInfo] if ctx.attrs.swift_toolchain else None,
+            watch_kit_stub_binary = ctx.attrs.watch_kit_stub_binary,
+            xcode_version = ctx.attrs.xcode_version,
+            xcode_build_version = ctx.attrs.xcode_build_version,
+        ),
+    ]