checkout: refactor die_if_checked_out() caller

There is a bit dense logic to make a call to "die_if_checked_out()"
while trying to check out a branch.  Extract it into a helper
function and give it a bit of comment to describe what is going on.

The most important part of the refactoring is the separation of the
guarding logic before making the call to die_if_checked_out() into
the caller specific part (e.g., the logic that decides that the
caller is trying to check out an existing branch) and the bypass due
to the "--ignore-other-worktrees" option.  The latter will be common
no matter how the current or future callers decides they need this
protection.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/checkout.c b/builtin/checkout.c
index f02434bc155ba1769a248350afa686322e6110bb..b4ab972c5ac8e1bccd6e4558855a3f4c8737ec2b 100644 (file)
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1516,6 +1516,26 @@ static void die_if_some_operation_in_progress(void)
        wt_status_state_free_buffers(&state);
 }
 
+/*
+ * die if attempting to checkout an existing branch that is in use
+ * in another worktree, unless ignore-other-wortrees option is given.
+ * The check is bypassed when the branch is already the current one,
+ * as it will not make things any worse.
+ */
+static void die_if_switching_to_a_branch_in_use(struct checkout_opts *opts,
+                                               const char *full_ref)
+{
+       int flags;
+       char *head_ref;
+
+       if (opts->ignore_other_worktrees)
+               return;
+       head_ref = resolve_refdup("HEAD", 0, NULL, &flags);
+       if (head_ref && (!(flags & REF_ISSYMREF) || strcmp(head_ref, full_ref)))
+               die_if_checked_out(full_ref, 1);
+       free(head_ref);
+}
+
 static int checkout_branch(struct checkout_opts *opts,
                           struct branch_info *new_branch_info)
 {
@@ -1576,15 +1596,9 @@ static int checkout_branch(struct checkout_opts *opts,
        if (!opts->can_switch_when_in_progress)
                die_if_some_operation_in_progress();
 
-       if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
-           !opts->ignore_other_worktrees) {
-               int flag;
-               char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
-               if (head_ref &&
-                   (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
-                       die_if_checked_out(new_branch_info->path, 1);
-               free(head_ref);
-       }
+       /* "git checkout <branch>" */
+       if (new_branch_info->path && !opts->force_detach && !opts->new_branch)
+               die_if_switching_to_a_branch_in_use(opts, new_branch_info->path);
 
        if (!new_branch_info->commit && opts->new_branch) {
                struct object_id rev;