Junio C Hamano <gitster@xxxxxxxxx> 于2023年8月3日周四 00:32写道：
>
> ZheNing Hu <adlternative@xxxxxxxxx> writes:
>
> >> --verify
> >> Verify that exactly one parameter is provided, and that it
> >> can be turned into a raw 20-byte SHA-1 that can be used to access the
> >> object database. If so, emit it to the standard output;
> >> otherwise, error out.
> >>
> >
> > So why doesn't "git rev-list --verify" check if 20-byte SHA-1 can
> > "access the object database"?
>
> Hysterical Raisins.
>
> "rev-parse" can do many things, and one of them is about expanding
> strings (like "9e4df4da", "jt/path-filter-fix", "seen~7^2", and
> "9e4df4da0786797b1d51ed8fd3dfc18970772a91") given from the command
> line into hexadecimal strings of the full length (they are often
> called "revision"). "--verify" tells the command that on the
> command line there must be ONE and only one "revision", give the
> full length hexadecimal string for it. The command fails if the
> command line argument cannot be turned into a hexadecimal string of
> the full length.
>
> Now, among the ones given as examples in the above, "9e4df4da",
> needs to look at the object database to turn it into a hexadecimal
> string of the full length, because it is likely to be an abbrevation
> (although it could be a branch name, too). "jt/path-filter-fix" and
> "seen~7^2" needs to look at the refs and probably into the object
> database (to see what the 7th generation grandparent is and what the
> second parent of that commit is) before they can be turned into
> hexadecimal strings of the full length.
>
> But "9e4df4da0786797b1d51ed8fd3dfc18970772a91" is already a full
> hexadecimal, so it is given back as a "revision" without checking if
> there is such an object in the object database.
>
Well, so the "git rev-parse --verify" command simply converts the revision
into a 20-byte SHA-1 without actually performing any real "verification", which
can be quite misleading.
> Checking if it can be turned into the form that can be used to query
> the object database, and checking the object database using it to
> find out if such an object exists, are two distinct steps low-level
> tool authors, who would want to use the plumbing tools, may need.
> The current option set allows the separation (and ^{object} suffix
> lets you do the both at the same time, too).
>
Thanks for the answer.
