The problem is very simple.
The generated .c file has
valac -C --pkg lua luatest.vala
which should be
I have found all lua headers in /usr/include/lua52,
but pkg-config for vala(c) cannot find them.
the error is
/home/aleksandar/Programing/ewns-viewer/ewns-viewer.vala.c:8:17: fatal error: lua.h: No such file or directory