Re: strange parser error

[Ethan A M. <sf...@us...>]

On Wednesday, October 31, 2012 01:06:12 pm Dima Kogan wrote:
> >
> > On Wednesday, October 31, 2012 08:33:01 am Karl-Friedrich Ratzsch
> > wrote:
> > > 
> > > i observe a strange parser error, where any command containing + or
> > > - would no longer be accepted. It first occured to me after a
> > > mistype with the stats commmand, and boils down to this:
> > > 
> > > gp> a=0
> > > gp> stats file"
> > > 	undefined variable: file
> > > gp> a=a+1
> > >        ^
> > > 	';' expected

> > On Wed, 31 Oct 2012 10:17:06 -0700
> > Ethan A Merritt <sf...@us...> wrote:
> > Indeed quite strange.  I see the same thing with 4.4.4 and with
> > the current 4.6 CVS source.  
> > 
> > But it doesn't happen in 4.7,  so bisecting the changes from
> > 4.6 to 4.7 should identify the source of the problem and 
> > provide a fix.

Dima Kogan wrote> 
> Git bisect says the fix happened in
> 
> https://github.com/gnuplot/gnuplot/commit/9b944c2cd4c59545ce3cc903fdb88f01a8ca6e1e
> 

This turns out to be a good example of when automatic bisection yields only
a hint, not a fix.  The commit you found (I found it also) did not actually remove
the problem. It changed 2 call sites, one in stats.c and one in fit.c, 
such that try_to_get_string() was replaced with a call to string_or_express().
After this change the specific commands provided by Karl-Friedrich Ratzsch 
no longer trigger the error, but other calls to try_to_get_string() were 
still vulnerable.

The underlying problem was a failure to reset internal parsing state variables
after an error exit from command line parsing.  
Now fixed in CVS for 4.6 and 4.7.
	
	Ethan