Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

IndexError in parse_tree_builder.py, release 0.10.0

See original GitHub issue

Describe the bug

I’m trying to parse a snippet and I get this error:

contrib/python/lark-parser/lark/lark.py:438: in parse
    return self.parser.parse(text, start=start)
contrib/python/lark-parser/lark/parser_frontends.py:215: in parse
    return self._parse(text, start)
contrib/python/lark-parser/lark/parser_frontends.py:58: in _parse
    return self.parser.parse(input, start, *args)
contrib/python/lark-parser/lark/parsers/earley.py:320: in parse
    return transformer.transform(solutions[0])
contrib/python/lark-parser/lark/parsers/earley_forest.py:353: in transform
    self.visit(root)
contrib/python/lark-parser/lark/parsers/earley_forest.py:295: in visit
    vpno(current)
contrib/python/lark-parser/lark/parsers/earley_forest.py:417: in visit_packed_node_out
    transformed = self.transform_packed_node(node, self.data[id(node)])
contrib/python/lark-parser/lark/parsers/earley_forest.py:559: in transform_packed_node
    return self._call_rule_func(node, children)
contrib/python/lark-parser/lark/parsers/earley_forest.py:521: in _call_rule_func
    return self.callbacks[node.rule](data)
contrib/python/lark-parser/lark/parse_tree_builder.py:124: in __call__
    filtered = children[i].children
E   IndexError: list index out of range

I can’t figure out what’s wrong, could you help me please?

To Reproduce

l = Lark(open('golang.lark').read(), start='go_file', regex=True)
l.parse("""
package x
func evalFrameHash(frame FrameData) norm.Hash {
h := [4]byte{0x5b, 0xd1, 0xe9, 0x95}
for i, b := range frame.FrameData() {
    h[i%4] ^= b
}
return norm.Hash{Data: h}
""")

grammar is here https://gist.github.com/grihabor/2014488c65cde5a5ef71fd61c13a75d6