Vendor dependencies

Let's see how I like this workflow.

vendor/cxx/tools/buck/prelude/tests/re_utils.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.
+
+def get_re_executor_from_props(re_props: [{str.type: str.type}, None]) -> ["command_executor_config_builder", None]:
+    """
+    Convert the `remote_execution` properties param into a `CommandExecutorConfig`
+    to use with test providers.
+    """
+
+    if re_props == None:
+        return None
+
+    return CommandExecutorConfig(
+        local_enabled = False,
+        remote_enabled = True,
+        remote_execution_properties = re_props,
+        remote_execution_use_case = "tpx-default",
+    )

vendor/cxx/tools/buck/prelude/tests/tpx_re_legacy.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", "expect")
+
+_RE_ENABLED = "supports_remote_execution"
+_RE_OPTS_LABEL_PREFIX = "re_opts_capabilities="
+_RE_OPTS_KEYS = ["platform", "subplatform"]
+
+def _parse_re_opts(labels: [str.type]) -> [{str.type: str.type}, None]:
+    """
+    Parse out JSON-embedded RE options like:
+    "re_opts_capabilities={\"platform\": \"gpu-remote-execution\", \"subplatform\": \"P100\"}"
+    """
+
+    for label in labels:
+        if label.startswith(_RE_OPTS_LABEL_PREFIX):
+            result = json.decode(label[len(_RE_OPTS_LABEL_PREFIX):])
+            for key in result.keys():
+                expect(key in _RE_OPTS_KEYS, "unexpected key in RE options label: {}", key)
+            return result
+
+    return None
+
+# TODO(agallagher): Parsing RE options via JSON embedded in labels isn't a great
+# UI, and we just do it here to support existing use cases.  Ideally, though, we'd
+# present a better UI (e.g. an `re_opts` param for tests) and use that instead.
+def get_re_executor_from_labels(labels: [str.type]) -> ["command_executor_config_builder", None]:
+    """
+    Parse legacy RE-enablement test labels and use them to configure a test RE
+    executor to run the test with.
+
+    The UI is best documented at:
+    https://www.internalfb.com/intern/wiki/Remote_Execution/Users/GPU_RE_Contbuild_Migration/
+    """
+
+    # If the special "RE enabled" label isn't present, abort.
+    if _RE_ENABLED not in labels:
+        return None
+
+    # If there's no options found in labels, don't use RE.  This diverges from
+    # v1 behavior, but v2+tpx needs some platform to be set and so we probably
+    # want to the toolchain tp provide some exec-platform compatible platform.
+    re_opts = _parse_re_opts(labels)
+    if re_opts == None:
+        return None
+
+    return CommandExecutorConfig(
+        local_enabled = False,
+        remote_enabled = True,
+        remote_execution_properties = re_opts,
+        remote_execution_use_case = "tpx-default",
+    )