Re: [LTP] flex warnings

[Manoj I. <ma...@au...>]

Dan,

I did some investigation on this some months ago trying to fix the 
broken scanner program, turns out this is a bug in flex.

Cheers
Manjo

> I'm having a look at the compiler warnings in an ltp build,
> and the first thing that shows up is a huge blort of flex
> warnings of the form
>
> "scan.l", line 111: warning, dangerous trailing context
> "scan.l", line 133: warning, dangerous trailing context
> "scan.l", line 160: warning, dangerous trailing context
> "scan.l", line 171: warning, dangerous trailing context
> "scan.l", line 179: warning, dangerous trailing context
> "scan.l", line 236: warning, dangerous trailing context
> "scan.l", line 97: warning, dangerous trailing context
>
> This warning is described at
> http://www.gnu.org/manual/flex-2.5.4/html_node/flex_23.html :
> "Some trailing context patterns cannot be properly matched
> and generate warning messages ("dangerous trailing context").
> These are patterns where the ending of the first part of the
> rule matches the beginning of the second part, such as
> "zx*/xy*", where the 'x*' matches the 'x' at the
> beginning of the trailing context. (Note that the POSIX
> draft states that the text matched by such patterns is
> undefined.)"
>
> Looking at scan.l, though, it's hard to see what flex is
> complaining about.  The pattern in line 97 is
> ^<<<rts_keyword_start>>>$
> The pattern at line 236 is
> <OUT>^.+$
> I'm no lex expert, so I don't quite see how those
> are ambiguous.
>
> Anyone know what's up with those warnings?
>
> Thanks,
> Dan
>
>