[BUG] OneOf attribute example is not working

[sk-]

In the OneOf docs it says:

Note that a OneOf matcher can be used anywhere you are defining a matcher attribute. So, an alternate form to the first example looks like:

m.Name(m.OneOf("True", "False"))

However, I'm not able to use that matcher, as I get the following error:

Traceback (most recent call last):
  File "cst/matcher_bug2.py", line 8, in <module>
    print(m.findall(node, matcher_oneof))
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1574, in findall
    nodes, _ = _find_or_extract_all(tree, matcher, metadata_resolver=metadata_resolver)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1539, in _find_or_extract_all
    tree.visit(finder)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/_nodes/base.py", line 225, in visit
    _CSTNodeSelfT, self._visit_and_replace_children(visitor)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/_nodes/statement.py", line 591, in _visit_and_replace_children
    test=visit_required(self, "test", self.test, visitor),
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/_nodes/internal.py", line 81, in visit_required
    result = node.visit(visitor)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/_nodes/base.py", line 216, in visit
    should_visit_children = visitor.on_visit(self)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1483, in on_visit
    match = _matches(node, self.matcher, self.metadata_lookup)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1352, in _matches
    return _node_matches(node, matcher, metadata_lookup)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1299, in _node_matches
    attribute_capture = _attribute_matches(actual, desired, metadata_lookup)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1113, in _attribute_matches
    sequence_capture = _sequence_matches(node, m, metadata_lookup)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1044, in _sequence_matches
    match_capture = _matches(node, matcher, metadata_lookup)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1352, in _matches
    return _node_matches(node, matcher, metadata_lookup)
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/libcst/matchers/_matcher_base.py", line 1282, in _node_matches
    for field in fields(matcher):
  File "/Users/user/.virtualenvs/cst/lib/python3.6/site-packages/dataclasses.py", line 972, in fields
    raise TypeError('must be called with a dataclass type or instance')
TypeError: must be called with a dataclass type or instance

This is the code I'm using to test it:

import libcst.matchers as m
import libcst

node = libcst.parse_statement("if True: continue")
matcher_oneof = m.OneOf(m.Name("True"), m.Name("False"))
matcher_oneof_attribute = m.Name(m.OneOf('True', 'False'))
matcher_matchiftrue = m.Name(m.MatchIfTrue(lambda value: value in ('True', 'False')))
print(m.findall(node, matcher_matchiftrue))
print(m.findall(node, matcher_oneof))
print(m.findall(node, matcher_oneof_attribute))

Note that the matcher_matchiftrue and the matcher_oneof matchers work fine in the example above.

[jimmylai]

The documentation is wrong. The options of OneOf need to be matchers (either concrete matcher node or some matcher helper node like OneOf/AllOf) instead of arbitrary type (like the str in the example).
We should fix the document.