Underscores in qualified names in HsParser

[Ross Paterson]

Anders Lau Olsen <alauo at mip.sdu.dk> writes:
> HsParser is confused by the combination of qualified names and
> identifiers starting with underscores. For example:
> 
>     module M where
> 
>     _f _ _ = 0
> 
>     x = 0 `M._f` 0 -- parse error at '.'
> 
>     y = M._f 0 0 -- parses as M . (_f 0 0)
> 
> I have tested this only for GHC 5.02. For what it's worth, I am pretty
> sure the later versions behave the same, and that the fix is to
> replace line 336 in Lexer.hs
> 
>     | isLower c -> do           -- qualified varid?
> 
> with
> 
>     | isLower c || c == '_' -> do       -- qualified varid?

Thanks for the report and fix.  I've applied this change in CVS.