"git branch --contains x y" creates a branch instead of checking containment

The "git branch --list --contains x y" command lists all branches that contains commit x and matches the pattern y. Reading the git-branch(1) manual page gives the impression that "--list" is redundant, and that you can instead write

    git branch --contains x y

That command does something completely different, though. The "--contains x" part is silently ignored, so it creates a branch named "y" pointing at HEAD.

Tested in git 1.8.1.1 and 1.8.1.4.

In my opinion, there are two ways to fix this:

  - change the "git branch" implementation so
    that --contains implies --list.

  - change the manual page synopsis so that
    it is clear that --contains can only be
    used if --list is also used.  Also add an
    error check to the "git branch" implementation
    so that using --contains without specifying
    --list produces a fatal error message.

Personally I would prefer the first solution.

Repeat by running these commands:

# Set up a repo with two commits. # Branch a points to the oldest one, and # b and master to the newest one. mkdir contains || exit 1 cd contains git init touch a; git add a; git commit -m"Added a". git branch a touch b; git add b; git commit -m"Added b". git branch b

git branch --list --contains a # Prints "a", "b" and "master, as expected.

git branch --contains a # Prints "a", "b" and "master, as expected. # In this case, the --list option can be removed.

git branch --list --contains a b # Prints "b", as expected. "b" is a <pattern>.

git branch --list --contains a c # Prints nothing, as expected, as the "c" pattern doesn't match any of # the existing branches.

git for-each-ref # Prints three lines: refs/heads/a, refs/heads/b and # refs/heads/master, as expected.

git branch --contains a c # Prints nothing, as expected, but...

git for-each-ref # Prints four lines! Apparently, the command above created # refs/heads/c.

     /ceder

P.S. What I really wanted to do was "git merge-base --is-ancestor a b", but I keep forgetting its name.