Marshall Clow via Boost
Calendar at https://www.boost.org/development
https://www.boost.org/development/tests/master/developer/locale.html
https://github.com/boostorg/locale/pull/15 is still not in "master" yet.
Despite the PR's title it'd fix "link" failures even for GCC e.g.,
### BEFORE ###
$ g++8 libs/locale/test/test_config.cpp -lboost_locale
/tmp//cc1DwEva.o: In function `main':
test_config.cpp:(.text+0x7cd): undefined reference to `boost::locale::generator::generator()'
test_config.cpp:(.text+0x88c): undefined reference to `boost::locale::generator::~generator()'
test_config.cpp:(.text+0x9b0): undefined reference to `boost::locale::generator::~generator()'
/tmp//cc1DwEva.o: In function `boost::locale::generator::operator()(std::__cxx11::basic_string