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-rwxr-xr-xgit-checkout.sh74
1 files changed, 60 insertions, 14 deletions
diff --git a/git-checkout.sh b/git-checkout.sh
index 92ec069..8f4356d 100755
--- a/git-checkout.sh
+++ b/git-checkout.sh
@@ -6,6 +6,7 @@ SUBDIRECTORY_OK=Sometimes
old_name=HEAD
old=$(git-rev-parse --verify $old_name 2>/dev/null)
+oldbranch=$(git-symbolic-ref $old_name 2>/dev/null)
new=
new_name=
force=
@@ -13,6 +14,8 @@ branch=
newbranch=
newbranch_log=
merge=
+LF='
+'
while [ "$#" != "0" ]; do
arg="$1"
shift
@@ -50,7 +53,7 @@ while [ "$#" != "0" ]; do
exit 1
fi
new="$rev"
- new_name="$arg^0"
+ new_name="$arg"
if git-show-ref --verify --quiet -- "refs/heads/$arg"
then
branch="$arg"
@@ -139,23 +142,49 @@ fi
[ -z "$new" ] && new=$old && new_name="$old_name"
-# If we don't have an old branch that we're switching to,
+# If we don't have an existing branch that we're switching to,
# and we don't have a new branch name for the target we
-# are switching to, then we'd better just be checking out
-# what we already had
+# are switching to, then we are detaching our HEAD from any
+# branch. However, if "git checkout HEAD" detaches the HEAD
+# from the current branch, even though that may be logically
+# correct, it feels somewhat funny. More importantly, we do not
+# want "git checkout" nor "git checkout -f" to detach HEAD.
-[ -z "$branch$newbranch" ] &&
- [ "$new" != "$old" ] &&
- die "git checkout: provided reference cannot be checked out directly
+detached=
+detach_warn=
- You need -b to associate a new branch with the wanted checkout. Example:
- git checkout -b <new_branch_name> $arg
-"
+if test -z "$branch$newbranch" && test "$new" != "$old"
+then
+ detached="$new"
+ if test -n "$oldbranch"
+ then
+ detach_warn="warning: you are not on ANY branch anymore.
+If you meant to create a new branch from the commit, you need -b to
+associate a new branch with the wanted checkout. Example:
+ git checkout -b <new_branch_name> $arg"
+ fi
+elif test -z "$oldbranch" && test -n "$branch"
+then
+ # Coming back...
+ if test -z "$force"
+ then
+ git show-ref -d -s | grep "$old" >/dev/null || {
+ echo >&2 \
+"You are not on any branch and switching to branch '$new_name'
+may lose your changes. At this point, you can do one of two things:
+ (1) Decide it is Ok and say 'git checkout -f $new_name';
+ (2) Start a new branch from the current commit, by saying
+ 'git checkout -b <branch-name>'.
+Leaving your HEAD detached; not switching to branch '$new_name'."
+ exit 1;
+ }
+ fi
+fi
if [ "X$old" = X ]
then
- echo "warning: You do not appear to currently be on a branch." >&2
- echo "warning: Forcing checkout of $new_name." >&2
+ echo >&2 "warning: You appear to be on a branch yet to be born."
+ echo >&2 "warning: Forcing checkout of $new_name."
force=1
fi
@@ -226,8 +255,25 @@ if [ "$?" -eq 0 ]; then
git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
branch="$newbranch"
fi
- [ "$branch" ] &&
- GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
+ if test -n "$branch"
+ then
+ GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
+ elif test -n "$detached"
+ then
+ # NEEDSWORK: we would want a command to detach the HEAD
+ # atomically, instead of this handcrafted command sequence.
+ # Perhaps:
+ # git update-ref --detach HEAD $new
+ # or something like that...
+ #
+ echo "$detached" >"$GIT_DIR/HEAD.new" &&
+ mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" ||
+ die "Cannot detach HEAD"
+ if test -n "$detach_warn"
+ then
+ echo >&2 "$detach_warn"
+ fi
+ fi
rm -f "$GIT_DIR/MERGE_HEAD"
else
exit 1