Before I look too deep: So I understand this only affects the sorting but does not add tags*? I previously understood that it adds tags for (private?) members that are declared in class declarations so that they can be autocompleted in the corresponding source file but not in other source files.
*: the new tm_tag_header_t only says "foo.h is included" so that we can later lookup foo.h and import tags from that file, right? So not a real tag but more of a pointer to a TMSourceFile?