When the N-th previous thing checked out syntax (@{-N}) is used
with '--branch' option of check-ref-format the result may not be
the name of a branch that currently exists or ever existed. This
is because @{-N} is used to refer to the N-th last checked out
"thing", which might be a commit object name if the previous check
out was a detached HEAD state; or a branch name, otherwise. The
documentation thus does a wrong thing by promoting it as the
"previous branch syntax".
State that @{-N} is the syntax for specifying "N-th last thing
checked out" and also state that the result of using @{-N} might
also result in an commit object name.
Signed-off-by: Kaartic Sivaraam <kaartic.sivaraam@xxxxxxxxx>
---
Changes in v4:
- updated the commit message
- made changes suggested by Junio
Documentation/git-check-ref-format.txt | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/Documentation/git-check-ref-format.txt b/Documentation/git-check-ref-format.txt
index cf0a0b7df..8172a6b9a 100644
--- a/Documentation/git-check-ref-format.txt
+++ b/Documentation/git-check-ref-format.txt
@@ -78,17 +78,21 @@ reference name expressions (see linkgit:gitrevisions[7]):
. at-open-brace `@{` is used as a notation to access a reflog entry.
With the `--branch` option, the command takes a name and checks if
-it can be used as a valid branch name (e.g. when creating a new
-branch). The rule `git check-ref-format --branch $name` implements
-may be stricter than what `git check-ref-format refs/heads/$name`
-says (e.g. a dash may appear at the beginning of a ref component,
-but it is explicitly forbidden at the beginning of a branch name).
-When run with `--branch` option in a repository, the input is first
-expanded for the ``previous branch syntax''
-`@{-n}`. For example, `@{-1}` is a way to refer the last branch you
-were on. This option should be used by porcelains to accept this
-syntax anywhere a branch name is expected, so they can act as if you
-typed the branch name.
+it can be used as a valid branch name e.g. when creating a new branch
+(but be cautious when using the previous checkout syntax; it may refer
+to a detached HEAD state). The rule `git check-ref-format --branch
+$name` implements may be stricter than what `git check-ref-format
+refs/heads/$name` says (e.g. a dash may appear at the beginning of a
+ref component, but it is explicitly forbidden at the beginning of a
+branch name). When run with `--branch` option in a repository, the
+input is first expanded for the ``previous checkout syntax''
+`@{-n}`. For example, `@{-1}` is a way to refer the last thing that
+was checked out using "git checkout" operation. This option should be
+used by porcelains to accept this syntax anywhere a branch name is
+expected, so they can act as if you typed the branch name. As an
+exception note that, the ``previous checkout operation'' might result
+in a commit object name when the N-th last thing checked out was not
+a branch.
OPTIONS
-------
@@ -116,7 +120,7 @@ OPTIONS
EXAMPLES
--------
-* Print the name of the previous branch:
+* Print the name of the previous thing checked out:
+
------------
$ git check-ref-format --branch @{-1}
--
2.15.0.531.g2ccb3012c
