fix(rsync): hardcode two-character options

completions/rsync

@@ -98,9 +98,27 @@ _comp_cmd_rsync()
                             awk 'sub(/^--?/,"--no-"){sub(/=$/,"");print}'
                     } | command grep -Exe "$(strings -d "$(type -P "$1")" 2>/dev/null | command sed -n '/[^-a-zA-Z0-9]/d;s/$/=?/;/^--[a-zA-Z]/p;s/^[a-zA-Z]/--&/p;s/^--no-/--/p')"
                 )"
-
+
+                # These options cannot be tested by "strings -d /path/to/rsync"
+                # because they are too short to extract using "strings".  We
+                # manually generate them when rsync is likely to suppor the feature.
+                local -a hardcoded_options=()
+                # * "--compress-choice" and its synonyms "--cc" and "--zc" are
+                #   available in rsync-3.2.0.
+                [[ " ${help_options[*]} " == *' --compress-choice= '* ]] &&
+                    hardcoded_options+=(--cc= --zc=)
+                # * The short name "--zl" for "--compress-level" has been
+                #   introduced in rsync-3.2.1.  We here abuse the fact that
+                #   another option "--early-info" is also introduced in
+                #   rsync-3.2.1.  We also confirm that rsync actually supports
+                #   the feature by checking the longer option.
+                [[ " ${help_options[*]} " == *' --early-info= '* ]] &&
+                    [[ " ${help_options[*]} " == *' --compress-level= '* ]] &&
+                    hardcoded_options+=(--zl=)
+
                 _comp_compgen -- -W '$(printf '%s\n' "${help_options[@]}" \
-                    "${confirmed_options[@]}" | sort -u)' -X '--no-OPTION'
+                    "${confirmed_options[@]}" "${hardcoded_options[@]}" | \
+                    sort -u)' -X '--no-OPTION'
             fi
             [[ ${COMPREPLY-} == *= ]] || compopt +o nospace
             ;;