Parse tree for ambiguous grammar contains `drv` subtree? about lark

[Michael0x2a]

@erezsh -- sorry for the delayed response. I can confirm that the code currently on master resolves my issue. Thanks for the fix!

@erezsh Sorry, my bad. I was using Lark - v0.6.6. It works on master!
Thanks!

[erezsh]

(Ignore my comment if you saw it. I will address this bug soon)

[erezsh]

Hi Michael,
Sorry it took me a while to get to this issue, and thank you for pointing out a bug in Lark's core.
I just pushed a fix to master. Let me know if it solves this issue.

Hi -- I still have this issue with the following grammar

from lark import Lark

grammar = '''
start :  "1"
      | "1" "+" start
      | start "-" start
      | "(" start ")"
      | "(" start ")" "-" start
'''

foo = '1+(1+1)-1'

parser = Lark(grammar, start='start', ambiguity='explicit')
print(parser.parse(foo))

Output -

Tree(_ambig, [
    Tree(start, [
        Tree(start, [
            Tree(start, [
                Tree(start, [
                    Tree(drv, [Token(__ANON_0, '1')])
                ])
            ])
        ]),
        Tree(start, [])
    ]),
    Tree(start, [
        Tree(start, [
            Tree(start, [
                Tree(start, [])
            ]),
            Tree(start, [])
        ])
    ]),
    Tree(start, [
        Tree(start, [
            Tree(start, [
                Tree(start, [
                    Tree(drv, [Token(__ANON_0, '1')])
                ])
            ]),
            Tree(start, [])
        ])
    ])
])

Lark Version - v0.7.0
Python - v3.7.3

Thanks!

[erezsh]

@anishparanjpe Are you sure about these versions? I can't reproduce it (with Python 3.7.0)