Many Qt ports require lrelease/lupdate to compile their translations. These programs are provided by qt4-linguist port, however that port provided much more that just these utilities, namely GUI applications for translation and pulls in many heavyweight depends, such as qt4-gui, qt4-assistant (which in turn pulls qt4-webkit, xml, network, sql etc.). With that, compiling a simple CLI application which just uses qt4-corelib (astro/gpsbabel for example) pulls in too much unneeded heavyweight and gui stuff.
That said, lrelease/lupdate should be split out of qt4-linguist, and corresponding USE_QT4 item added so qt applications using nls may be build without pulling extraneous depends.
I just hit this with net-p2p/bitcoin, which uses linguist_build for exactly this reason, which then results (among others) in the following dependency chain:
linguist_build -> linguist -> designer -> webkit
+1 on splitting out lrelease & lupdate
Created attachment 153399 [details]
initial patch to splitout tools
[propably still needs some work].
A commit references this bug:
Date: Tue Feb 24 21:39:23 UTC 2015
New revision: 379843
Introduce new USE_QT4 component linguisttools for lrelease/lupdate tools
split from from devel/qt4-linguist (similar to Qt 5 ports). These console
tools are often used for localization support in Qt ports, having them
standalone is quite useful. This work is based on Tobias Berner patch .
PR: 190929 
Requested by: amdmi3, koobs
Folks, feel free to convert existing ports.
Tobias, thanks for patch!
Yes, thank you Tobias :)