Is this a bug? --with-png=DIR not supported

[Chris Pudney]

G'day,

I'm building gnuplot 4.3 on a CentOS 4 system where libgd (v2.0.35) and libpng (v1.2.8) are installed in non-standard locations, i.e. not /usr/lib nor /usr/local/lib.

The documentation suggests one ought to be able to run

configure --with-gd=GD_HOME --with-png=PNG_HOME

but this is clearly not the case.

$ ./configure  --with-png=/apps/web/server8000/libpng --with-gd=/apps/web/server8000/libgd
...
checking for gdlib-config... no
checking for gdImageCreate in -lgd... yes
checking gd.h usability... yes
checking gd.h presence... yes
checking for gd.h... yes
checking for gdImageGif in -lgd... yes
...
checking for gdImagePng in -lgd... no
...
** Configuration summary for gnuplot 4.3:

gnuplot will be compiled with the following terminals:

  Standalone terminals: yes (always builtin)
...
  png terminal: no (requires libgd with png support)
    (jpeg, gif and png terminals cannot use TTF fonts, requires libgd support)
...
$

Looking at configure.in it's clear that --with-png is ignored (./configure --help confirms it).

The workaround I'm using is

./configure --with-gd=/apps/web/server8000/libgd LDFLAGS='-L/apps/web/server8000/libpng/lib'

Also need to

export LD_LIBRARY_PATH=/apps/web/server8000/libgd/lib:/apps/web/server8000/libpng/lib

to get make check to work.

My question is: should --with-png=DIR be reinstated to make it possible to build gnuplot when libpng is in a non-standard location?

Thanks,
Chris.