Re: [RFC] Using a display_info union instead of a typedef Display_Info

[Paul Eggert <eggert@cs.ucla.edu>]

Thanks, this looks like a step in the right direction. I have a few
minor quibbles: function names like U_DISPLAY_INFO_X shouldn't be
lowercase, and more important DISPLAY_INFO/display_info should be a
function and not a macro, and it should return a pointer to new generic
type, 'struct generic_display_info' say, that contains only the leading
elements common to all the structures - and all the structures should be
changed to have a first member of that generic type. See the first
members of 'struct Lisp_Vector' and 'struct Lisp_Char_Table' for an
example of this.

I have my doubts about installing this in master now, as it doesn't have
direct benefit now. Ironically, one of the patches I have in mind (which
should improve overall Emacs performance significantly) involves
reverting a patch installed some years ago that was intended to be a
refactoring to do later work that was never done. So I appreciate Eli's
concern about merging this into master right away.

However, the patch seems to be a good candidate for installing into a
scratch branch that later patches can improve on, and once that branch
has direct benefits we could merge that into master.