https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60799
--- Comment #2 from Casey Carter <Casey at Carter dot net> --- [basic.lookup.unqual]/9 says that name *lookup* inside friend functions defined inline works as it does in member functions, but that doesn’t necessarily imply that the friend function should have the same *access* as member functions would to the names so found (excepting, of course, names of the class being defined). Given [class.friend]/2: Declaring a class to be a friend implies that the names of private and protected members from the class granting friendship can be accessed in the base-specifiers and member declarations of the befriended class. and [class.mem]/1: … Except when used to declare friends (11.3), to declare an unnamed bit-field (9.6), or to introduce the name of a member of a base class into a derived class (7.3.3), or when the declaration is an empty-declaration, member-declarations declare members of the class, and each such member-declaration shall declare at least one member name of the class. … It's "clear" that a friend declaration is a member-declaration which – oddly enough – does not declare a member. So the critical question is whether the wording “and member declarations” in [class.friend]/2 means “declarations that are syntactically member-declarations” or “declarations of members.” I'm inclined to the second interpretation, which would imply the behavior described in this bug report is what the standard intends.
