#include "submodule.h"
#include "advice.h"
+static int checkout_optimize_new_branch;
+
static const char * const checkout_usage[] = {
N_("git checkout [<options>] <branch>"),
N_("git checkout [<options>] [<branch>] -- <file>..."),
int ignore_skipworktree;
int ignore_other_worktrees;
int show_progress;
+ /*
+ * If new checkout options are added, skip_merge_working_tree
+ * should be updated accordingly.
+ */
const char *new_branch;
const char *new_branch_force;
if (pos >= 0) {
struct cache_entry *old = active_cache[pos];
if (ce->ce_mode == old->ce_mode &&
- !oidcmp(&ce->oid, &old->oid)) {
+ oideq(&ce->oid, &old->oid)) {
old->ce_flags |= CE_UPDATE;
discard_cache_entry(ce);
return 0;
branch->path = strbuf_detach(&buf, NULL);
}
+/*
+ * Skip merging the trees, updating the index and working directory if and
+ * only if we are creating a new branch via "git checkout -b <new_branch>."
+ */
+static int skip_merge_working_tree(const struct checkout_opts *opts,
+ const struct branch_info *old_branch_info,
+ const struct branch_info *new_branch_info)
+{
+ /*
+ * Do the merge if sparse checkout is on and the user has not opted in
+ * to the optimized behavior
+ */
+ if (core_apply_sparse_checkout && !checkout_optimize_new_branch)
+ return 0;
+
+ /*
+ * We must do the merge if we are actually moving to a new commit.
+ */
+ if (!old_branch_info->commit || !new_branch_info->commit ||
+ !oideq(&old_branch_info->commit->object.oid,
+ &new_branch_info->commit->object.oid))
+ return 0;
+
+ /*
+ * opts->patch_mode cannot be used with switching branches so is
+ * not tested here
+ */
+
+ /*
+ * opts->quiet only impacts output so doesn't require a merge
+ */
+
+ /*
+ * Honor the explicit request for a three-way merge or to throw away
+ * local changes
+ */
+ if (opts->merge || opts->force)
+ return 0;
+
+ /*
+ * --detach is documented as "updating the index and the files in the
+ * working tree" but this optimization skips those steps so fall through
+ * to the regular code path.
+ */
+ if (opts->force_detach)
+ return 0;
+
+ /*
+ * opts->writeout_stage cannot be used with switching branches so is
+ * not tested here
+ */
+
+ /*
+ * Honor the explicit ignore requests
+ */
+ if (!opts->overwrite_ignore || opts->ignore_skipworktree ||
+ opts->ignore_other_worktrees)
+ return 0;
+
+ /*
+ * opts->show_progress only impacts output so doesn't require a merge
+ */
+
+ /*
+ * If we aren't creating a new branch any changes or updates will
+ * happen in the existing branch. Since that could only be updating
+ * the index and working directory, we don't want to skip those steps
+ * or we've defeated any purpose in running the command.
+ */
+ if (!opts->new_branch)
+ return 0;
+
+ /*
+ * new_branch_force is defined to "create/reset and checkout a branch"
+ * so needs to go through the merge to do the reset
+ */
+ if (opts->new_branch_force)
+ return 0;
+
+ /*
+ * A new orphaned branch requrires the index and the working tree to be
+ * adjusted to <start_point>
+ */
+ if (opts->new_orphan_branch)
+ return 0;
+
+ /*
+ * Remaining variables are not checkout options but used to track state
+ */
+
+ return 1;
+}
+
static int merge_working_tree(const struct checkout_opts *opts,
struct branch_info *old_branch_info,
struct branch_info *new_branch_info,
parse_commit_or_die(new_branch_info->commit);
}
- ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
- if (ret) {
- free(path_to_free);
- return ret;
+ /* optimize the "checkout -b <new_branch> path */
+ if (skip_merge_working_tree(opts, &old_branch_info, new_branch_info)) {
+ if (!checkout_optimize_new_branch && !opts->quiet) {
+ if (read_cache_preload(NULL) < 0)
+ return error(_("index file corrupt"));
+ show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
+ }
+ } else {
+ ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
+ if (ret) {
+ free(path_to_free);
+ return ret;
+ }
}
if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
static int git_checkout_config(const char *var, const char *value, void *cb)
{
+ if (!strcmp(var, "checkout.optimizenewbranch")) {
+ checkout_optimize_new_branch = git_config_bool(var, value);
+ return 0;
+ }
+
if (!strcmp(var, "diff.ignoresubmodules")) {
struct checkout_opts *opts = cb;
handle_ignore_submodules_arg(&opts->diff_options, value);