gcc supports type checks for printf parameters which can catch some hard
to reproduce bugs. Possible bugs happen when the parameter value is
intepreted differently to the variable value.
Example warnings follow
../library/LuaWrapper.cpp:1011:86: warning: format ‘%llu’ expects argument
of type ‘long long unsigned int’, but argument 3 has type ‘uint64_t
{aka long unsigned int}’ [-Wformat=]
../plugins/follow.cpp:159:35: warning: format not a string literal and no
format arguments [-Wformat-security]
The mask argument of the Impl template is there because apparently
an inner template cannot be fully specialized, so there needs to be
some argument besides i.