https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120106
--- Comment #15 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > '=' can be overridden on the command line, but overrides the environment and > previous assignments (when a Makefile #includes another one). Environment variables should be avoided in favor of command line assignments, and nested Makefile invocations should make use of them too.
