g++ 6 is stricter regarding narrowing conversions in initializer
lists. This causes errors similar to the following during compilation
with the gcc6 or gcc7 overlays:
locationinfo.cpp:163:21: error: narrowing conversion of '237'
from 'int' to 'char' inside { } [-Wnarrowing]
This has already been fixed upstream in several consecutive patches,
but there's no release including those fixes yet. This patch consists
of the essence of said fixes.
Tony Theodore
Moritz Bunkus