loose dependency

[Tijl Coosemans]

On Thu, 14 Mar 2019 19:09:40 +0900 Koichiro Iwao <meta at FreeBSD.org>
wrote:
> On Thu, Mar 14, 2019 at 04:50:18PM +0900, Hiroki Sato wrote:
>> That is a workaround while increasing maintenance cost.  It is at the
>> maintainer's discretion.
> 
> Thanks for the advice. Fortunely, icons are not updated too open. The
> maintenance cost is not negligible but might be acceptable.

Like hrs already said: since this is a build dependency you can just
write:

BUILD_DEPENDS=	convert:graphics/ImageMagick6

This does not install ImageMagick6 if 7 is installed.  It will only
install 6 if convert does not exist.  It is a loose dependency.

This is not the case for RUN_DEPENDS because dependencies in a package
are currently specified using package names (including version).  They
would have to be specified using features where multiple packages can
then provide a feature.

port1:
PROVIDES=	feature1 feature2

port2:
PROVIDES=	feature2

port3:
RUN_DEPENDS=	feature2:category/port1

Then pkg could see if any installed packages provide feature2 and only
install port1 by default.