Re: [Caml-list] Segfault with open GADTs

[Goswin von Brederlow <goswin-v-b@web.de>]

On Tue, Oct 18, 2016 at 11:52:40AM -0200, Andre Nathan wrote:
> On 10/18/2016 11:10 AM, Pierrick Couderc wrote:
> > Hi,
> > 
> > It is supposed to work, but it seems thepattern-matching compiler does
> > not detect that M0.to_string is non exhaustive, thus it does not add a
> > Match_Failure in case the variant is unknown. With extensible variants,
> > a pattern matching is only exhaustive if you provide a wildcard or a
> > variable for variants added afterwards. 
> 
> 
> Indeed, if I add a catch-all branch in M0.to_string then the code in
> that branch is run, with no segfault.
> 
> But I guess my original idea of extending the type doesn't really work
> as I hoped, since with nested expressions like that, I'd need to find a
> way for M0.to_string to call back M1.to_string when a `T` is found.
> 
> Back to the drawing board...
> 
> Thanks,
> Andre

You can pass along the outermost to_string to all to_string
functions so they can restart from the outside when they recurse.

MfG
	Goswin