bug#49827: Error message for missing synopsis in opam importer

[Alice BRENON <alice.brenon@ens-lyon.fr>]

Hello,

Thanks for your answer !

Le Tue, 17 Aug 2021 09:43:10 +0200,
zimoun <zimon.toutoune@gmail.com> a écrit :

> Hi,
> 
> I am back from holidays. :-)
> 
> …   
> 
> From my understanding, there is 2 issues:  
> 
>  - gentle handler for error
>  - warn for incomplete metadata
> 

Yes, absolutely, because currently understanding the cause of the error
requires to delve into the source to understand what is going on. The
warning part is more optional, but if this pattern matching is modified
to handle that special case of a missing metadata instead of entirely
crashing, I thought it could be useful not to be too permissive either,
and to at least mention that a missing metadata was caught and should
be filled by hand.

This could take the form of a message above the output of the actual
scheme code for the package declaration while the importer is running,
or of an invalid value for that missing field in the generated scheme
output, something like "<FILL-ME>" or such that would be invalid in
scheme and would make guix build fail when trying to use the output
directly without manually editing it to fill the missing metadata.

> With Jérémy (jeko), we have started to work time to time using
> experimental pair-programming to fix the former.  Currently, each
> importer uses its own error mechanism and obviously incoherence
> between them happens; especially when ’--recursive’.  We are trying
> to unify that.
> 
> Thanks for the report of this use case. :-)

Glad to learn my report could help : )

> 
> 
> Cheers,
> simon