Vendor dependencies

Let's see how I like this workflow.

vendor/cxx/tools/buck/prelude/ide_integrations/xcode.bzl

@@ -0,0 +1,31 @@
+# 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.
+
+XCODE_DATA_SUB_TARGET = "xcode-data"
+_XCODE_DATA_FILE_NAME = "xcode_data.json"
+
+XcodeDataInfo = provider(fields = [
+    "data",  # {str.type: _a}
+])
+
+def generate_xcode_data(
+        ctx: "context",
+        rule_type: str.type,
+        output: ["artifact", None],
+        populate_rule_specific_attributes_func: ["function", None] = None,
+        **kwargs) -> (["DefaultInfo"], XcodeDataInfo.type):
+    data = {
+        "rule_type": rule_type,
+        "target": ctx.label,
+    }
+    if output:
+        data["output"] = output
+    if populate_rule_specific_attributes_func:
+        data.update(populate_rule_specific_attributes_func(ctx, **kwargs))
+
+    json_file = ctx.actions.write_json(_XCODE_DATA_FILE_NAME, data)
+    return [DefaultInfo(default_outputs = [json_file])], XcodeDataInfo(data = data)