Re: obstack: fix license problem

[Bruno Haible]

Hi Simon,

> Using the obstack module results in warnings:
> 
> warning: module obstack depends on a module with an incompatible license: exit
> warning: module obstack depends on a module with an incompatible license: 
> exitfail
> 
> The reason appears to be because obstack is 'LGPL' while exit and
> exitfail is 'GPL'.

Yes, this is so, unfortunately.

> Would you agree to re-license this module to 'LGPL'?

This is the wrong approach, IMO. If you are using 'obstack' in a library,
you don't _want_ it to call exit(). You need to change the 'obstack' module -
locally, via a local override - so that it can not call exit any more.

Paul Eggert and I wanted to do this long ago, but didn't find a _general_
solution that would serve GPLed and LGPLed projects equally and yet be simple.

Changing the licenses of 'exit' and 'exitfail' to LGPL would be the wrong
approach, because then people would ask for all gnulib to become LGPL,
piece by piece: first 'exit', then 'xmalloc', etc. etc.

> Bruno, your 'exit' module looks strange: it doesn't do anything except
> depending on stdlib.  It used to provide exit.h, but no longer does so.
> Can't we simply remove the 'exit' module and suggest users to use the
> stdlib module directly instead?

We could in theory, but a few modules (copy-file, exitfail, pipe, xsetenv etc.)
depend on it. I find it quite clear to say: "if you need the exit() function,
take the 'exit' module". Clearer than to say: "... take the 'stdlib' module".

Bruno