Questions about configure/building regarding Qt and Lua

[Daniel J S. <dan...@ie...>]

I upgraded to Mint 18.2 here, and I'm going through all the usually 
system rebuilding...

Why does configure report:

checking for QT... yes
configure: WARNING: The Qt terminal will use Qt5.

Is it simply because Qt5 is considered experimental support at this stage?

Also, when compiling I ran into a missing lrelease utility for Qt:

c++  -g -O2 -I/usr/lib/x86_64-linux-gnu/wx/include/gtk2-unicode-3.0 
-I/usr/include/wx-3.0 -D_FILE_OFFSET_BITS=64 -DWXUSINGDLL -D__WXGTK__ 
-pthread -I/usr/include/pango-1.0 -I/usr/include/harfbuzz 
-I/usr/include/pango-1.0 -I/usr/include/cairo -I/usr/include/glib-2.0 
-I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 
-I/usr/include/freetype2 -I/usr/include/libpng12 -fPIC   -lcerf  -o 
gnuplot_qt qtterminal/gnuplot_qt.o qtterminal/QtGnuplotWindow.o 
qtterminal/QtGnuplotApplication.o qtterminal/QtGnuplotWidget.o 
qtterminal/QtGnuplotScene.o qtterminal/QtGnuplotItems.o 
qtterminal/QtGnuplotEvent.o qtterminal/moc_QtGnuplotWindow.o 
qtterminal/moc_QtGnuplotApplication.o qtterminal/moc_QtGnuplotWidget.o 
qtterminal/moc_QtGnuplotScene.o qtterminal/moc_QtGnuplotEvent.o 
qtterminal/qrc_QtGnuplotResource.o -lQt5Network -lQt5Svg 
-lQt5PrintSupport -lQt5Widgets -lQt5Gui -lQt5Core -ldl -lm -lcerf  -lz 
-lpangocairo-1.0 -lpango-1.0 -lgobject-2.0 -lcairo -lglib-2.0
/usr/lib/x86_64-linux-gnu/qt5/bin/lrelease 
/home/sebald/gnuplot/gnuplot/gnuplot/src/qtterminal/po/qtgnuplot_fr.ts 
-qm qtgnuplot_fr.qm
/bin/bash: /usr/lib/x86_64-linux-gnu/qt5/bin/lrelease: No such file or 
directory
Makefile:1282: recipe for target 'qtgnuplot_fr.qm' failed
make[4]: *** [qtgnuplot_fr.qm] Error 127

Should configure check for that lrelease file that is being included? 
It isn't too much trouble to find the package and install lrelease 
(qttools5-dev-tools), but that package isn't automatically installed 
with all the other Qt5 packages as a requirement.  After installing 
qttools5-dev-tools, compilation continues with 29 translations for Qt.

I then ran into this problem:

make[2]: Entering directory '/usr/local/src/gnuplot/gnuplot/build1/docs'
lua5.2 /home/sebald/gnuplot/gnuplot/gnuplot/term/lua/gnuplot-tikz.lua 
termhelp > gnuplot-tikz.help
/bin/bash: lua5.2: command not found
Makefile:979: recipe for target 'gnuplot-tikz.help' failed
make[2]: *** [gnuplot-tikz.help] Error 127

which is of the same variety as the previous problem.  I had to install 
lua5.2 package because it isn't a requirement for liblua5.2-dev package. 
  Should configure check for the lua executable?

sebald@ ~/gnuplot/gnuplot/gnuplot $ lua5.2 -v
Lua 5.2.4  Copyright (C) 1994-2015 Lua.org, PUC-Rio

Dan