Re: Bug: git ls-remote -h / --head results differ in output

From: Martin Ågren <martin.agren@gmail.com>
Date: Oct 15, 2017, 11:08 UTC
Message-ID: <CAN0heSpPWWdWY4d1wCdRH8TjcmD3kAiSffL0-_9kJWkm5P2EkA@mail.gmail.com>
In-Reply-To: <63fe2a84-d991-9165-32c0-8087d8513ce6@online.de>

On 15 October 2017 at 12:02, Thomas Rikl <trikl@online.de> wrote:

Show 35 quoted lines

> Example:
>
> tom1 ~/emacs/spacemacs/.emacs.d $ export LANG=en_US.utf8
>
> tom1 ~/emacs/spacemacs/.emacs.d $ git ls-remote -h
> usage: git ls-remote [--heads] [--tags] [--refs] [--upload-pack=<exec>]
>                      [-q | --quiet] [--exit-code] [--get-url]
>                      [--symref] [<repository> [<refs>...]]
>
>     -q, --quiet           do not print remote URL
>     --upload-pack <exec>  path of git-upload-pack on the remote host
>     -t, --tags            limit to tags
>     -h, --heads           limit to heads
>     --refs                do not show peeled tags
>     --get-url             take url.<base>.insteadOf into account
>     --exit-code           exit with exit code 2 if no matching refs are
> found
>     --symref              show underlying ref in addition to the object
> pointed by it
>
> tom1 ~/emacs/spacemacs/.emacs.d $ git ls-remote --head
> From https://github.com/syl20bnr/spacemacs
> 07014deead544c51fa6a826e91fe2ef05bf04323 refs/heads/develop
> 8e1af145480d53e8d32cdff2c83291889903164b refs/heads/master
> 2450b7e276634ece07b6b7ec6ca6c287af86caf3 refs/heads/release-0.101
> 8dadfc1494544bb152e80c2a436e43bc3713b389 refs/heads/release-0.102
> d993a021847cde2c42865bab6afa8adbb2edda0b refs/heads/release-0.103
> 44d4525543b1f2a385142721d0cb16cd3b0be580 refs/heads/release-0.104
> 9f9faa404e3dec3e08cc73cf7b5a0439fc309800 refs/heads/release-0.105
> 8e1af145480d53e8d32cdff2c83291889903164b refs/heads/release-0.200
> tom1 ~/emacs/spacemacs/.emacs.d $ git --version
> git version 2.14.2
>
> on archlinux: Linux achse 4.13.5-1-ARCH #1 SMP PREEMPT Fri Oct 6 09:58:47
> CEST 2017 x86_64 GNU/Linux

The behavior you observed matches with the documentation in gitcli(7) and is arguably correct. A lone "-h" prints the help/usage. But I would agree that this can be confusing, especially when considering git-ls-remote(1) on its own, without any extra knowledge about what a lone -h should do.

So -h and --heads can only be used interchangeably if you have other arguments. To see this, you could, e.g., try "git ls-remote -h -h".

Some more details. This looks like ba5f28bf7 (ls-remote: use parse-options api, 2016-01-19). Before that, "-h" was handled internally in builtin/ls-files.c. After that it is handled in the general options-parsing machinery. See for example 5ad0d3d52 (parse-options: allow -h as a short option, 2015-11-17), which explicitly wants to print the usage-string if "-h" is given as the lone argument.

I'm not sure which is the best way forward here, or how many other commands could have similar pitfalls. For example, the "-h"-flag of git grep shouldn't be able to cause this problem.

Martin