Completion must sort before using uniq
authorMarc Khouzam <marc.khouzam@gmail.com>
Fri, 23 Nov 2012 14:02:22 +0000 (09:02 -0500)
committerJunio C Hamano <gitster@pobox.com>
Sun, 25 Nov 2012 06:35:48 +0000 (22:35 -0800)
The user can be presented with invalid completion results
when trying to complete a 'git checkout' command. This can happen
when using a branch name prefix that matches multiple remote branches.

For example, if available branches are:
master
remotes/GitHub/maint
remotes/GitHub/master
remotes/origin/maint
remotes/origin/master

When performing completion on 'git checkout ma' the user will be
given the choices:
maint
master

However, 'git checkout maint' will fail in this case, although
completion previously said 'maint' was valid. Furthermore, when
performing completion on 'git checkout mai', no choices will be
suggested. So, the user is first told that the branch name
'maint' is valid, but when trying to complete 'mai' into 'maint',
that completion is no longer valid.

The completion results should never propose 'maint' as a valid
branch name, since 'git checkout' will refuse it.

The reason for this bug is that the uniq program only
works with sorted input. The man page states
"uniq prints the unique lines in a sorted file".

When __git_refs uses the guess heuristic employed by checkout for
tracking branches it wants to consider remote branches but only if
the branch name is unique. To do that, it calls 'uniq -u'. However
the input given to 'uniq -u' is not sorted.

Therefore, in the above example, when dealing with 'git checkout ma',
"__git_refs '' 1" will find the following list:
master
maint
master
maint
master

which, when passed to 'uniq -u' will remain the same. Therefore
'maint' will be wrongly suggested as a valid option.

When dealing with 'git checkout mai', the list will be:
maint
maint

which happens to be sorted and will be emptied by 'uniq -u',
properly ignoring 'maint'.

A solution for preventing the completion script from suggesting
such invalid branch names is to first call 'sort' and then 'uniq -u'.

Signed-off-by: Marc Khouzam <marc.khouzam@gmail.com>
Reviewed-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
contrib/completion/git-completion.bash
index be800e09bdf0656951c415105e0d32ce0b0edf9e..48c3abdf987f0843b7886372a374be19a669398d 100644 (file)
@@ -321,7 +321,7 @@ __git_refs ()
                                if [[ "$ref" == "$cur"* ]]; then
                                        echo "$ref"
                                fi
-                       done | uniq -u
+                       done | sort | uniq -u
                fi
                return
        fi