[GRASS-dev] Configuring --with-readline doesn't use -lncurses or -ltermcap

[Glynn Clements]

Gregor Mosheh wrote:

> Hi, all. I encountered a problem configuring --with-readline A workaround
> exists in the mailing list archives, but since the problem still exists
> almost 2 years after the workaround was posted, sholl asked me to post it
> to the devel list to bring it to your attention.
> 
> Problem:
> When --with-readline is supplied, configure reports that readline was not
> found.
> 
> Analysis:
> Examining the config.log, the compile of conftest.c includes the
> -lreadline flag, but does not include either -lncurses or -ltermcap which
> is required for GNU readline. The result is linking errors to the effect
> of "undefined reference to `tgetnum'" et al.
> 
> Workaround:
> Set LDFLAGS in the environment to force -lncurses

Yuk. That will add a ncurses dependency to every single library and
executable.

> http://grass.itc.it/pipermail/grassuser/2005-February/027824.html
> 
> Ideal:
> Have configure detect whether to use -lncurses or else -ltermcap, and have
> it use that flag, so configure will properly link with readline and thus
> detect it.

How is it meant to know *which* library to use? Both provide the
necessary functions (as does -ltinfo if you have that library), but
they don't necessarily behave the same (particularly on platforms
other than Linux, where e.g. -ltermcap may actually use the termcap
database while -lncurses may use the terminfo database).

Ideal:
The OS vendor adds the correct library as a dependency of libreadline.

On my system (Gentoo):

$ ldd /lib/libreadline.so
	linux-gate.so.1 =>  (0xffffe000)
	libncurses.so.5 => /lib/libncurses.so.5 (0xb7f65000)
	libc.so.6 => /lib/libc.so.6 (0xb7e4c000)
	/lib/ld-linux.so.2 (0x80000000)

--with-readline works fine here.

I consider this a WONTFIX until someone comes up with a coherent
answer to the question of how to choose amongst multiple competing
"providers" of tgetent etc.

On a related note: how many people actually feed complex expressions
to r.mapcalc via stdin?

-- 
Glynn Clements <glynn at gclements.plus.com>