[Slackbuilds-users] 'AC_CHECK_LIB([readline]' fails on 14.2

[Nate Bargmann]

* On 2018 27 Jan 14:10 -0600, B Watson wrote:

> These symbols are defined in libncurses. Normally when anything links
> with readline, it also links with ncurses... you could probably have
> figured this out yourself, by reading the man page for tputs (it tells
> you it's part of curses anyway, which would have been a strong hint).
> 
> (I just re-read what I wrote above, and it sounds kinda smarmy... it
> isn't meant that way, it's supposed to be helpful & educational. I hate
> just giving an answer, would rather give the reasoning behind it.)

Not a problem.  :-)

I've had more experience in the Debian world, and I recognized that
tputs probably had to do with terminfo but since Slackware uses termcap,
I mentally stopped there.

> You can fix the problem in lxi-tools by adding LIBS="-lncurses" to the
> configure command. With standard SBo template, it would look like:
> 
> LIBS="-lncurses"
> CFLAGS="$SLKCFLAGS" \
> CXXFLAGS="$SLKCFLAGS" \
> ./configure \
>   --prefix=/usr \
>   <...other options here...>

That will be far more elegant than the solution I arrived at which was
to patch configure.ac and Makefile.am, make an m4 directory and copy the
ax_lib_readline.m4 into the m4 directory, and rerun autoreconf -f -i
which did actually work!  Passing LIBS this way is much better.

> When I run configure this way, I still can't build lxi-tools since I
> don't have the lxi library it depends on, but I do get:

Using my convoluted method above, I did get lxi-tools to build and was
able to discover and grab a screenshot from my oscilloscope.

> Interestingly, this isn't just a problem for lxi-tools. Anything that
> tries to link with -lreadline but not -lncurses will fail in the same
> way on 14.2:

I package Hamlib and in it we use readline, but also use the
ax_lib_readline.m4 macro as part of our upstream so I didn't hit this
problem last year.  That threw me for a bit of a curve as well.

> Clear as mud, yes?

Oh yeah.  ;-)

I hadn't made the connection of the tie in between ncurses and tinfo
although I know they are closely related.  Next time I can RTFM a bit
more!

Anyway, thanks much for the thorough explanation.  Sometimes a refresher
is needed no matter how much we think we know!

- Nate

-- 

"The optimist proclaims that we live in the best of all
possible worlds.  The pessimist fears this is true."

Ham radio, Linux, bikes, and more: http://www.n0nb.us
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