The code in XKeycodeToKeysym that made indexes greater than 3 refer to XKB symbol groups had an off-by-one error, so it would always leave out the symbol that should have been at index 4. Rewrite the code to fix this and simplify the logic a bit.
This was originally diagnosed by firk in bugs.freedesktop.org 5349, which was migrated to GitLab as #97 (closed).
Using the XKeycodeToKeysym.c testcase from that bug, with a French keymap (setxkbmap fr), here's the original output:
0 22
1 33
2 0
3 0
4 A3
5 0
6 0
7 0
8 0 And here's the output with this patch applied (note 23 is now included in the right place):
0 22
1 33
2 0
3 0
4 23
5 A3
6 0
7 0
8 0 Fixes #97 (closed).