This option controls the visibility of
In C++, it controls whether or not the name of a class or
function that is declared only in
is visible when using the normal lookup mechanisms.
friend names are declared, they are
visible to these lookups. When
friend names are
not declared as required by the standard, function names are visible
only when using argument-dependent lookup, and class names are never
--friend_injection is provided
only as a migration aid for legacy source code that does not conform
to the C++ standard. Its use is not recommended.