From: Eric Sunshine <sunshine@sunshineco.com>
Date: Sat, 07 Mar 2026 07:06:01 GMT
Subject: Re: [PATCH v3 1/3] branch: add '--name-prefix' option
Message-ID: <CAPig+cRQcA+0yWqbYMfjFXxhTsQ-tjJEqsVFudu1thuYi3AXUw@mail.gmail.com>
In-Reply-To: <6cbb950d8bc3b647d7fff72a72f938ee369b552c.1772802872.git.gitgitgadget@gmail.com>

On Fri, Mar 6, 2026 at 8:15 AM VALERI Yoann via GitGitGadget
<gitgitgadget@gmail.com> wrote:
> This patch adds a '--name-prefix' option to add a prefix to a newly
> created branch. It can use a regular string or a token as prefix. The
> only token currently handled is '@{current}', which is substituted for
> the current branch's name.
>
> Signed-off-by: VALERI Yoann <yoann.valeri@cea.fr>
> ---
> diff --git a/Documentation/git-branch.adoc b/Documentation/git-branch.adoc
> @@ -64,6 +65,10 @@ Note that this will create the new branch, but it will not switch the
> +With a `--name-prefix` option, you can add a prefix to the branch to create.
> +This can either a simple name, or a token. Currently, only '@{current}' is
> +managed as token, and will use the current branch name as prefix.

s/This can/& be/

> diff --git a/branch.c b/branch.c
> @@ -365,6 +365,23 @@ int read_branch_desc(struct strbuf *buf, const char *branch_name)
> +void add_branch_prefix(const char *name_prefix,
> +                                          const char *current_branch, struct strbuf *buf)
> +{
> +       int value = 0;

What is `value`? It doesn't seem to be used at all in this function.

> +       if (!name_prefix)
> +               return;
> +
> +       if (name_prefix[0] != '@') {
> +               strbuf_addstr(buf, name_prefix);
> +               return;
> +       }
> +
> +       if (strcmp(name_prefix, "@{current}") == 0)
> +               strbuf_addstr(buf, current_branch);
> +}

I would expect this function to produce some sort of diagnostic
warning when the user has given it a "@{token}" it doesn't recognize.

> diff --git a/branch.h b/branch.h
> @@ -148,6 +148,18 @@ int install_branch_config(int flag, const char *local, const char *origin, const
> +/*
> + * Store in 'buf' a prefix to the name of a branch to create by using the given
> + * string 'name_prefix'. It can either be a simple string to a shorthand
> + * starting with '@'.
> + *
> + * Currently, only '@{current}' is managed, and will use 'current_branch' as
> + * prefix.
> + */
> +void add_branch_prefix(const char *name_prefix, const char *current_branch,
> +                                          struct strbuf *buf);

It feels unnecessarily burdensome to force the caller to compute and
pass in `current_branch`. Intuitively, one would expect
add_branch_prefix() to compute the current branch itself if it
discovers that "@{current}" has been requested.

Moveover, this approach will not scale well when support for
additional "@{tokens}" is added down the road since it burdens *all*
callers with providing the values for *all* possible tokens.

> diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
> @@ -1716,4 +1716,22 @@ test_expect_success 'errors if given a bad branch name' '
> +test_expect_success 'create branch with --name-prefix' '
> +       git config branch.autosetupmerge false &&

Let's use `test_config` which will ensure that this setting is
reverted at the end of the test.


> +       git branch branch-with-prefix &&
> +       git branch --name-prefix "blob" -- -with-prefix &&
> +       test_must_fail git branch --name-prefix "blob" -- -with-prefix &&
> +       git branch --name-prefix "@{current}" -- -with-prefix &&
> +       git switch blob-with-prefix &&
> +       git branch --name-prefix "@{current}" -- -with-prefix &&
> +       test_must_fail git branch --name-prefix "@{current}" -- -with-prefix &&
> +       test_ref_exists refs/heads/branch-with-prefix &&
> +       test_ref_exists refs/heads/main-with-prefix &&
> +       test_ref_exists refs/heads/blob-with-prefix &&
> +       test_ref_exists refs/heads/blob-with-prefix-with-prefix &&
> +       git checkout main &&
> +       git branch -D branch-with-prefix main-with-prefix blob-with-prefix &&
> +       git branch -D blob-with-prefix-with-prefix
> +'