Ambiguous fallbacks not resolved across groups

[felixSchl]

Failing test case

r"""
Usage: foo
  or: foo (--input=FILE)
Options: --input [env: INPUT]
"""

$ INPUT=bar prog
{"--input": "bar"}

Fails with: Unexpected output: - empty - (incorrectly matches first usage branch, rather than second)

This is because fallback scores are only kept for one group parse and then discarded, they must somehow be propagated until they reach a terminal group parse.

This should be a fairly easy fix in

neodoc/src/Language/Docopt/ParserGen/Parser.purs

Lines 647 to 679 in 848a2b5

	genParser x@(D.Group optional bs repeated) canSkip = do
	vs <- concat <$>
	let mod = if optional then P.try >>> P.option mempty else \p -> p
	parser = if repeated then goR else singleton <$> go
	in mod parser
	return $ score 0 vs
	where
	goR :: Parser (List (List ValueMapping))
	goR = do
	{score, result} <- unScoredResult
	<$> genBranchesParser bs
	false
	optsFirst
	-- always allow skipping for non-free groups.
	(not (D.isFree x) || canSkip)
	if (length (snd result) == 0)
	then return $ singleton (snd result)
	else do
	xs <- goR <|> pure Nil
	return $ (snd result) : xs
	go :: Parser (List ValueMapping)
	go = if length bs == 0
	then return mempty
	else do
	snd <<< _.result <<< unScoredResult
	<$> genBranchesParser bs
	false
	optsFirst
	-- always allow skipping for
	-- non-free groups.
	(not (D.isFree x) || canSkip)

.

goR must somehow fold <> and go must return the full result ({ score, result }).