Cabal bug

[Duncan Coutts]

On Fri, 2007-08-03 at 20:34 +0100, Simon Peyton-Jones wrote:
> I have not been following the recent work on Cabal, but I tried to
> build in the gap before this patch was committed.  I 
> 
> Fri Aug  3 18:57:01 GMT Daylight Time 2007  Thomas Schilling
> <nominolo at gmail.com>
> 
>   * Fix tab in Cabal.cabal.

> 
> I was surprised to find that tabs are disallowed in cabal files.  Is
> that really the intention?

Yes, since the new configurations format is layout sensitive.

So tabs are disallowed in initial whitespace in cabal files that use the
new features. Existing files should not be affected.

>   It seems like a pitfall for the unwary!  At the very least, if they
> must be disallowed, could the error message be more informative?  At
> the moment we get 

Yes, Thomas fixed that just now,

>                 Setup.exe: Cabal.cabal:70: Unrecognized field format:
> 'Distribution.Simple.SetupWrapper,'
> 
> It’d be better to get
> 
>                 Setup.exe: Cabal.cabal:70: illegal tab character:
> replace with spaces

the error message is now:

setup: Cabal.cabal:70: Tabs used for indentation at (line,column):
[(70,0),(71,1)]

That was for a test case where tabs were used in two places of course.

Duncan