"git checkout <commit>" will checkout the commit in question and detach HEAD from the current branch. It is naturally a right thing to do once you get git references. But detached HEAD is a scary concept to new users because we show a lot of warnings and stuff, and it could be hard to get out of (until you know better). To keep switch a bit more friendly to new users, we only allow entering detached HEAD mode when --detach is given. "git switch" must take a branch (unless you create a new branch, then of course switch can take any commit-ish) Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx> --- builtin/checkout.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/builtin/checkout.c b/builtin/checkout.c index e9dfe38d69..4416b82bfd 100644 --- a/builtin/checkout.c +++ b/builtin/checkout.c @@ -45,6 +45,7 @@ struct checkout_opts { int merge; int force; int force_detach; + int implicit_detach; int writeout_stage; int overwrite_ignore; int ignore_skipworktree; @@ -1298,6 +1299,29 @@ static int switch_unborn_to_new_branch(const struct checkout_opts *opts) return status; } +static void die_expecting_a_branch(const struct branch_info *branch_info) +{ + struct object_id oid; + char *to_free; + + if (dwim_ref(branch_info->name, strlen(branch_info->name), &oid, &to_free) == 1) { + const char *ref = to_free; + + if (skip_prefix(ref, "refs/tags/", &ref)) + die(_("a branch is expected, got tag '%s'"), ref); + if (skip_prefix(ref, "refs/remotes/", &ref)) + die(_("a branch is expected, got remote branch '%s'"), ref); + die(_("a branch is expected, got '%s'"), ref); + } + if (branch_info->commit) + die(_("a branch is expected, got commit '%s'"), branch_info->name); + /* + * This case should never happen because we already die() on + * non-commit, but just in case. + */ + die(_("a branch is expected, got '%s'"), branch_info->name); +} + static int checkout_branch(struct checkout_opts *opts, struct branch_info *new_branch_info) { @@ -1345,6 +1369,14 @@ static int checkout_branch(struct checkout_opts *opts, !opts->force_detach) die(_("missing branch or commit argument")); + if (!opts->implicit_detach && + !opts->force_detach && + !opts->new_branch && + !opts->new_branch_force && + new_branch_info->name && + !new_branch_info->path) + die_expecting_a_branch(new_branch_info); + if (new_branch_info->path && !opts->force_detach && !opts->new_branch && !opts->ignore_other_worktrees) { int flag; @@ -1602,6 +1634,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix) opts.no_dwim_new_local_branch = 0; opts.switch_branch_doing_nothing_is_ok = 1; opts.accept_pathspec = 1; + opts.implicit_detach = 1; options = parse_options_dup(checkout_options); options = add_common_options(&opts, options); @@ -1633,6 +1666,7 @@ int cmd_switch(int argc, const char **argv, const char *prefix) opts.no_dwim_new_local_branch = 0; opts.accept_pathspec = 0; opts.switch_branch_doing_nothing_is_ok = 0; + opts.implicit_detach = 0; options = parse_options_dup(switch_options); options = add_common_options(&opts, options); -- 2.21.0.479.g47ac719cd3