Re: [Lightning] On `LIGHTNING_CONFIGURE_IF_NOT_FOUND'

[Ludovic Courtès]

Hi,

Paolo Bonzini <address@hidden> writes:

>>> @code{LIGHTNING_CONFIGURE_IF_NOT_FOUND} will first look for a
>>> pre-installed copy of @lightning{} and, if it can be found, it will
>>> use it; otherwise, it will do exactly the same things that
>>> @lightning{}'s own configure script does.
> ... s/do exactly.*/try to find a compatible back-end for the copy of
> lightning in your package's source directory/.
>
> Sounds ok?

Perfect.

>>>   If @lightning{} is
>>> already installed, or if the configuration process succeeds,
> s/the configuration process succeeds/the system is supported by lightning/

Ok.

>> Anyway, I'd rewrite lines 26 and 37 of `lightning.m4' as follows:
>>
>>   if test -n "$cpu_subdir" && test -d "lightning"; then
>>
> It could be an idea.  But I could also give a hard error if "test -d
> lightning" fails.

Handling of the not-found situation should be left to the user.
Actually, according to the M4 file, the exact usage of the macro is
exactly this:

  LIGHTNING_CONFIGURE_IF_NOT_FOUND([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])

(It invokes $1 and $2 at the end.)

So one can use `AC_MSG_ERROR' as they see fit as an ACTION-IF-NOT-FOUND.

Perhaps the parameters of this macro should be documented as well.  :-)

> If you don't want a drop-in lightning, you can use only
>
> AC_CHECK_HEADERS([lightning.h])
>
> Can't you?

Yeah, but I'm not supposed to know that
`LIGHTNING_CONFIGURE_IF_NOT_FOUND' does no more than this.  :-)

Thanks,
Ludovic.