On 3/7/22 18:22, Lv Ying via GNU gzip discussion and bug reports. wrote:

> However this manual separation job can not handle filename before options.
> ...
> getopt command from util-linux can handle such situation

We try to keep gzip portable to a wide variety of platforms, even those 
with ancient shells that lack getopt. I reworked zdiff.in to handle 
filenames before options (without using getopt) and installed the 
attached additional patch.

Please let us know of further problems by replying to this email and 
cc'ing to 54290@debbugs.gnu.org (there should be no need to open a new 
bug report).