am: improve author-script error reporting
[gitweb.git] / builtin / checkout.c
index 29ef50013dccbd118093af0b4dc08eb907953cc2..902c06702c62258384692f94ed6b55ecf6381a4e 100644 (file)
@@ -25,6 +25,8 @@
 #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>..."),
@@ -42,6 +44,10 @@ struct checkout_opts {
        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;
@@ -96,7 +102,7 @@ static int update_some(const struct object_id *oid, struct strbuf *base,
        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;
@@ -472,6 +478,99 @@ static void setup_branch_path(struct branch_info *branch)
        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,
@@ -846,10 +945,19 @@ static int switch_branches(const struct checkout_opts *opts,
                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)
@@ -864,6 +972,11 @@ static int switch_branches(const struct checkout_opts *opts,
 
 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);