Vendor dependencies

Let's see how I like this workflow.

vendor/cxx/tools/buck/prelude/user/all.bzl

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+# 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/user:apple_resource_bundle.bzl", _apple_resource_bundle_spec = "registration_spec")
+load("@prelude//apple/user:apple_toolchain_override.bzl", _apple_toolchain_override_spec = "registration_spec")
+load("@prelude//apple/user:apple_tools.bzl", _apple_tools_spec = "registration_spec")
+load("@prelude//apple/user:apple_watchos_bundle.bzl", _apple_watchos_bundle_spec = "registration_spec")
+load("@prelude//apple/user:resource_group_map.bzl", _resource_group_map_spec = "registration_spec")
+load("@prelude//cxx/user:link_group_map.bzl", _link_group_map_spec = "registration_spec")
+load(":extract_archive.bzl", _extract_archive_spec = "registration_spec")
+
+_all_specs = [
+    _extract_archive_spec,
+    _apple_tools_spec,
+    _apple_resource_bundle_spec,
+    _link_group_map_spec,
+    _resource_group_map_spec,
+    _apple_watchos_bundle_spec,
+    _apple_toolchain_override_spec,
+]
+
+rules = {s.name: rule(impl = s.impl, attrs = s.attrs, **{k: v for k, v in {"cfg": s.cfg}.items() if v != None}) for s in _all_specs}
+
+# The rules are accessed by doing module.name, so we have to put them on the correct module.
+load_symbols(rules)

vendor/cxx/tools/buck/prelude/user/extract_archive.bzl

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+# 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//utils:utils.bzl", "value_or")
+load(":rule_spec.bzl", "RuleRegistrationSpec")
+
+# Buck v2 doesn't support directories as source inputs, while v1 allows that.
+# This rule fills that gap and allows to produce a directory from archive,
+# which then can be used as an input for other rules.
+
+def _impl(ctx: "context") -> ["provider"]:
+    output = ctx.actions.declare_output(value_or(ctx.attrs.directory_name, ctx.label.name))
+    archive = ctx.attrs.contents_archive
+    script, _ = ctx.actions.write(
+        "unpack.sh",
+        [
+            cmd_args(output, format = "mkdir -p {}"),
+            cmd_args(output, format = "cd {}"),
+            cmd_args(archive, format = "tar -xzf {}").relative_to(output),
+        ],
+        is_executable = True,
+        allow_args = True,
+    )
+    ctx.actions.run(cmd_args(["/bin/sh", script])
+        .hidden([archive, output.as_output()]), category = "extract_archive")
+
+    return [DefaultInfo(default_outputs = [output])]
+
+registration_spec = RuleRegistrationSpec(
+    name = "extract_archive",
+    impl = _impl,
+    attrs = {
+        # .tar.gz archive with the contents of the result directory
+        "contents_archive": attrs.source(),
+        # name of the result directory, if omitted, `name` attribute will be used instead
+        "directory_name": attrs.option(attrs.string()),
+    },
+)

vendor/cxx/tools/buck/prelude/user/rule_spec.bzl

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+# 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.
+
+RuleRegistrationSpec = record(
+    name = field(str.type),
+    impl = field("function"),
+    attrs = field({str.type: "attribute"}),
+    cfg = field([None, "transition"], None),
+)