--diff-merges=, --no-diff-merges, --remerge-diff valuable options are absent for 'git range-diff' completion.

These are the options presented here:

|# Options accepted by log and show
__git_log_show_options="
         --diff-merges --diff-merges= --no-diff-merges --dd --remerge-diff
         --encoding=
"|

But they are not included for range-diff:

|_git_range_diff ()
{
         case "$cur" in
         --*)
                 __gitcomp "
                         --creation-factor= --no-dual-color
                         $__git_diff_common_options
                 "
                 return
                 ;;
         esac
         __git_complete_revlist
}|

[System Info] git version 2.53.0