From: Harald Nordgren via GitGitGadget Date: Tue, 12 May 2026 10:55:07 GMT Subject: [PATCH v9] checkout: extend --track with a "fetch" mode to refresh start-point Message-ID: In-Reply-To: From: Harald Nordgren If you want to fork your topic branch from the very latest of the tip of a branch your remote has, you would do: git fetch origin some-branch git checkout -b new_branch --track origin/some-branch Extend the "--track" option of "git checkout" and allow users to write git checkout -b new_branch --track=fetch origin/some-branch to (1) fetch 'some-branch' from the remote 'origin', updating the remote-tracking branch 'origin/some-branch', (2) arrange subsequent 'git pull' on 'new_branch' to interact with 'origin/some-branch' and (3) fork 'new_branch' from it. In the value of the '--track' option, 'fetch' can be combined with the existing 'direct' (default) and 'inherit' modes via a comma-separated list. Examples: git checkout -b new_branch --track=fetch,inherit some_local_branch git switch -c new_branch --track=fetch origin/some-branch When "fetch" is requested and is in / form, run "git fetch " before resolving the ref, so that other remote-tracking branches are left untouched. If is a bare remote name like "origin" (which resolves to that remote's default branch), "git fetch " is run instead, since the target branch is not known up front. Abort the checkout if the fetch fails. Signed-off-by: Harald Nordgren --- checkout: --track=fetch * Support hierarchical remote names (e.g. nested/remote) by trying the longest prefix first. * Fold the existing-ref lookup into resolve_fetch_target() so it returns the ref name directly. Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2281%2FHaraldNordgren%2Fcheckout-fetch-start-point-v9 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2281/HaraldNordgren/checkout-fetch-start-point-v9 Pull-Request: https://github.com/git/git/pull/2281 Range-diff vs v8: 1: 61c2199fd5 ! 1: 021375e4cc checkout: extend --track with a "fetch" mode to refresh start-point @@ builtin/checkout.c: struct branch_info { }; +static int resolve_fetch_target(const char *arg, char **remote_out, -+ char **src_ref_out) ++ char **src_ref_out, char **existing_ref_out) +{ + const char *slash; -+ char *remote_name; -+ struct remote *remote; ++ char *remote_name = NULL; ++ struct remote *remote = NULL; + struct refspec_item query = { 0 }; + struct strbuf dst = STRBUF_INIT; -+ const char *rest; ++ struct object_id oid; ++ const char *rest = NULL; ++ const char *head_target = NULL; ++ const char *short_target; + + *remote_out = NULL; + *src_ref_out = NULL; ++ *existing_ref_out = NULL; + -+ if (!arg || !*arg) -+ return -1; -+ -+ slash = strchr(arg, '/'); -+ if (slash == arg) ++ if (!arg || !*arg || *arg == '/') + return -1; -+ remote_name = slash ? xstrndup(arg, slash - arg) : xstrdup(arg); + -+ remote = remote_get(remote_name); -+ if (!remote || !remote_is_configured(remote, 1)) { ++ slash = arg + strlen(arg); ++ while (1) { + free(remote_name); -+ return -1; ++ remote_name = xstrndup(arg, slash - arg); ++ remote = remote_get(remote_name); ++ if (remote && remote_is_configured(remote, 1)) ++ break; ++ while (slash > arg && *--slash != '/') ++ ; ++ if (slash == arg) { ++ free(remote_name); ++ return -1; ++ } + } + -+ rest = (slash && slash[1]) ? slash + 1 : NULL; ++ if (*slash == '/' && slash[1]) ++ rest = slash + 1; + if (!rest) { -+ struct object_id oid; -+ const char *head_target; -+ const char *short_target; -+ + strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name); + head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository), + dst.buf, + RESOLVE_REF_READING | + RESOLVE_REF_NO_RECURSE, + &oid, NULL); ++ if (head_target) { ++ *existing_ref_out = xstrdup(dst.buf); ++ if (skip_prefix(head_target, "refs/remotes/", &short_target) && ++ skip_prefix(short_target, remote_name, &short_target) && ++ *short_target == '/') ++ rest = short_target + 1; ++ } + strbuf_reset(&dst); -+ if (head_target && -+ skip_prefix(head_target, "refs/remotes/", &short_target) && -+ skip_prefix(short_target, remote_name, &short_target) && -+ *short_target == '/') -+ rest = short_target + 1; + } + + if (rest) { @@ builtin/checkout.c: struct branch_info { + } else { + *src_ref_out = xstrdup(rest); + } ++ if (!*existing_ref_out) { ++ strbuf_reset(&dst); ++ strbuf_addf(&dst, "refs/remotes/%s", arg); ++ if (!refs_read_ref(get_main_ref_store(the_repository), ++ dst.buf, &oid)) ++ *existing_ref_out = xstrdup(dst.buf); ++ } + } + + strbuf_release(&dst); @@ builtin/checkout.c: struct branch_info { +{ + char *remote_name = NULL; + char *src_ref = NULL; ++ char *existing_ref = NULL; + struct child_process cmd = CHILD_PROCESS_INIT; -+ struct strbuf dst_ref = STRBUF_INIT; -+ int have_existing_ref = 0; + -+ if (resolve_fetch_target(arg, &remote_name, &src_ref)) ++ if (resolve_fetch_target(arg, &remote_name, &src_ref, &existing_ref)) + return; + -+ { -+ struct object_id oid; -+ -+ if (strchr(arg, '/')) -+ strbuf_addf(&dst_ref, "refs/remotes/%s", arg); -+ else -+ strbuf_addf(&dst_ref, "refs/remotes/%s/HEAD", arg); -+ if (!refs_read_ref(get_main_ref_store(the_repository), -+ dst_ref.buf, &oid)) -+ have_existing_ref = 1; -+ } -+ + strvec_pushl(&cmd.args, "fetch", remote_name, NULL); + if (src_ref) + strvec_push(&cmd.args, src_ref); + cmd.git_cmd = 1; + if (run_command(&cmd)) { -+ if (have_existing_ref) ++ if (existing_ref) + warning(_("failed to fetch start-point '%s'; " + "using existing '%s'"), -+ arg, dst_ref.buf); ++ arg, existing_ref); + else + die(_("failed to fetch start-point '%s'"), arg); + } + + free(remote_name); + free(src_ref); -+ strbuf_release(&dst_ref); ++ free(existing_ref); +} + +static int parse_opt_checkout_track(const struct option *opt, @@ builtin/checkout.c: struct branch_info { static void branch_info_release(struct branch_info *info) { free(info->name); -@@ builtin/checkout.c: static int git_checkout_config(const char *var, const char *value, - opts->dwim_new_local_branch = git_config_bool(var, value); - return 0; - } -- - if (starts_with(var, "submodule.")) - return git_default_submodule_config(var, value, NULL); - @@ builtin/checkout.c: static struct option *add_common_switch_branch_options( { struct option options[] = { @@ t/t7201-co.sh: test_expect_success 'tracking info copied with autoSetupMerge=inh + test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD +' + ++test_expect_success 'checkout --track=fetch handles hierarchical remote name' ' ++ git checkout main && ++ git -C fetch_upstream checkout -b fetch_hier && ++ test_commit -C fetch_upstream u_hier && ++ git remote add nested/remote ./fetch_upstream && ++ test_when_finished "git remote remove nested/remote" && ++ git fetch nested/remote fetch_hier && ++ test_commit -C fetch_upstream u_hier_post && ++ git checkout --track=fetch -b local_hier nested/remote/fetch_hier && ++ test_cmp_rev refs/remotes/nested/remote/fetch_hier HEAD ++' ++ +test_expect_success 'checkout --track=inherit,direct is rejected' ' + test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err && + test_grep "cannot combine" err Documentation/git-checkout.adoc | 13 ++- Documentation/git-switch.adoc | 13 ++- builtin/checkout.c | 168 +++++++++++++++++++++++++++++++- t/t7201-co.sh | 144 +++++++++++++++++++++++++++ 4 files changed, 332 insertions(+), 6 deletions(-) diff --git a/Documentation/git-checkout.adoc b/Documentation/git-checkout.adoc index 43ccf47cf6..28f17f427e 100644 --- a/Documentation/git-checkout.adoc +++ b/Documentation/git-checkout.adoc @@ -158,11 +158,22 @@ of it"). resets __ to the start point instead of failing. `-t`:: -`--track[=(direct|inherit)]`:: +`--track[=(direct|inherit|fetch)[,...]]`:: When creating a new branch, set up "upstream" configuration. See `--track` in linkgit:git-branch[1] for details. As a convenience, --track without -b implies branch creation. + +The argument is a comma-separated list. `direct` (the default) and +`inherit` select the tracking mode and are mutually exclusive. Adding +`fetch` requests that the remote be fetched before __ is +resolved, so the new branch starts from a fresh tip: when +__ is in _/_ form, only that branch is +updated; when __ is a bare remote name (e.g. `origin`), +only the remote's default branch is updated. If the fetch fails and the +corresponding remote-tracking ref already exists, a warning is printed +and the checkout proceeds from the existing tip; otherwise the checkout +is aborted. ++ If no `-b` option is given, the name of the new branch will be derived from the remote-tracking branch, by looking at the local part of the refspec configured for the corresponding remote, and then stripping diff --git a/Documentation/git-switch.adoc b/Documentation/git-switch.adoc index 87707e9265..3f54cf39e9 100644 --- a/Documentation/git-switch.adoc +++ b/Documentation/git-switch.adoc @@ -154,11 +154,22 @@ should result in deletion of the path). attached to a terminal, regardless of `--quiet`. `-t`:: -`--track[ (direct|inherit)]`:: +`--track[=(direct|inherit|fetch)[,...]]`:: When creating a new branch, set up "upstream" configuration. `-c` is implied. See `--track` in linkgit:git-branch[1] for details. + +The argument is a comma-separated list. `direct` (the default) and +`inherit` select the tracking mode and are mutually exclusive. Adding +`fetch` requests that the remote be fetched before __ is +resolved, so the new branch starts from a fresh tip: when +__ is in _/_ form, only that branch is +updated; when __ is a bare remote name (e.g. `origin`), +only the remote's default branch is updated. If the fetch fails and the +corresponding remote-tracking ref already exists, a warning is printed +and the switch proceeds from the existing tip; otherwise the switch is +aborted. ++ If no `-c` option is given, the name of the new branch will be derived from the remote-tracking branch, by looking at the local part of the refspec configured for the corresponding remote, and then stripping diff --git a/builtin/checkout.c b/builtin/checkout.c index ac0186a33e..aff442c526 100644 --- a/builtin/checkout.c +++ b/builtin/checkout.c @@ -26,10 +26,12 @@ #include "preload-index.h" #include "read-cache.h" #include "refs.h" +#include "refspec.h" #include "remote.h" #include "repo-settings.h" #include "resolve-undo.h" #include "revision.h" +#include "run-command.h" #include "setup.h" #include "strvec.h" #include "submodule.h" @@ -62,6 +64,7 @@ struct checkout_opts { int count_checkout_paths; int overlay_mode; int dwim_new_local_branch; + int fetch; int discard_changes; int accept_ref; int accept_pathspec; @@ -113,6 +116,158 @@ struct branch_info { char *checkout; }; +static int resolve_fetch_target(const char *arg, char **remote_out, + char **src_ref_out, char **existing_ref_out) +{ + const char *slash; + char *remote_name = NULL; + struct remote *remote = NULL; + struct refspec_item query = { 0 }; + struct strbuf dst = STRBUF_INIT; + struct object_id oid; + const char *rest = NULL; + const char *head_target = NULL; + const char *short_target; + + *remote_out = NULL; + *src_ref_out = NULL; + *existing_ref_out = NULL; + + if (!arg || !*arg || *arg == '/') + return -1; + + slash = arg + strlen(arg); + while (1) { + free(remote_name); + remote_name = xstrndup(arg, slash - arg); + remote = remote_get(remote_name); + if (remote && remote_is_configured(remote, 1)) + break; + while (slash > arg && *--slash != '/') + ; + if (slash == arg) { + free(remote_name); + return -1; + } + } + + if (*slash == '/' && slash[1]) + rest = slash + 1; + if (!rest) { + strbuf_addf(&dst, "refs/remotes/%s/HEAD", remote_name); + head_target = refs_resolve_ref_unsafe(get_main_ref_store(the_repository), + dst.buf, + RESOLVE_REF_READING | + RESOLVE_REF_NO_RECURSE, + &oid, NULL); + if (head_target) { + *existing_ref_out = xstrdup(dst.buf); + if (skip_prefix(head_target, "refs/remotes/", &short_target) && + skip_prefix(short_target, remote_name, &short_target) && + *short_target == '/') + rest = short_target + 1; + } + strbuf_reset(&dst); + } + + if (rest) { + strbuf_addf(&dst, "refs/remotes/%s/%s", remote_name, rest); + query.dst = dst.buf; + if (!remote_find_tracking(remote, &query) && query.src) { + *src_ref_out = xstrdup(query.src); + free(query.src); + } else { + *src_ref_out = xstrdup(rest); + } + if (!*existing_ref_out) { + strbuf_reset(&dst); + strbuf_addf(&dst, "refs/remotes/%s", arg); + if (!refs_read_ref(get_main_ref_store(the_repository), + dst.buf, &oid)) + *existing_ref_out = xstrdup(dst.buf); + } + } + + strbuf_release(&dst); + *remote_out = remote_name; + return 0; +} + +static void fetch_remote_for_start_point(const char *arg) +{ + char *remote_name = NULL; + char *src_ref = NULL; + char *existing_ref = NULL; + struct child_process cmd = CHILD_PROCESS_INIT; + + if (resolve_fetch_target(arg, &remote_name, &src_ref, &existing_ref)) + return; + + strvec_pushl(&cmd.args, "fetch", remote_name, NULL); + if (src_ref) + strvec_push(&cmd.args, src_ref); + cmd.git_cmd = 1; + if (run_command(&cmd)) { + if (existing_ref) + warning(_("failed to fetch start-point '%s'; " + "using existing '%s'"), + arg, existing_ref); + else + die(_("failed to fetch start-point '%s'"), arg); + } + + free(remote_name); + free(src_ref); + free(existing_ref); +} + +static int parse_opt_checkout_track(const struct option *opt, + const char *arg, int unset) +{ + struct checkout_opts *opts = opt->value; + struct string_list tokens = STRING_LIST_INIT_DUP; + struct string_list_item *item; + int saw_direct = 0, saw_inherit = 0; + int ret = 0; + + opts->fetch = 0; + + if (unset) { + opts->track = BRANCH_TRACK_NEVER; + return 0; + } + + opts->track = BRANCH_TRACK_EXPLICIT; + if (!arg) + return 0; + + string_list_split(&tokens, arg, ",", -1); + for_each_string_list_item(item, &tokens) { + if (!strcmp(item->string, "fetch")) { + opts->fetch = 1; + } else if (!strcmp(item->string, "direct")) { + saw_direct = 1; + opts->track = BRANCH_TRACK_EXPLICIT; + } else if (!strcmp(item->string, "inherit")) { + saw_inherit = 1; + opts->track = BRANCH_TRACK_INHERIT; + } else { + ret = error(_("option `%s' expects \"%s\", \"%s\", " + "or \"%s\""), + "--track", "direct", "inherit", "fetch"); + goto out; + } + } + + if (saw_direct && saw_inherit) + ret = error(_("option `%s' cannot combine \"%s\" and \"%s\""), + "--track", "direct", "inherit"); + +out: + string_list_clear(&tokens, 0); + return ret; +} + static void branch_info_release(struct branch_info *info) { free(info->name); @@ -1741,10 +1896,10 @@ static struct option *add_common_switch_branch_options( { struct option options[] = { OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")), - OPT_CALLBACK_F('t', "track", &opts->track, "(direct|inherit)", + OPT_CALLBACK_F('t', "track", opts, "(direct|inherit|fetch)[,...]", N_("set branch tracking configuration"), PARSE_OPT_OPTARG, - parse_opt_tracking_mode), + parse_opt_checkout_track), OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"), PARSE_OPT_NOCOMPLETE), OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unborn branch")), @@ -1949,8 +2104,13 @@ static int checkout_main(int argc, const char **argv, const char *prefix, opts->dwim_new_local_branch && opts->track == BRANCH_TRACK_UNSPECIFIED && !opts->new_branch; - int n = parse_branchname_arg(argc, argv, dwim_ok, which_command, - &new_branch_info, opts, &rev); + int n; + + if (opts->fetch) + fetch_remote_for_start_point(argv[0]); + + n = parse_branchname_arg(argc, argv, dwim_ok, which_command, + &new_branch_info, opts, &rev); argv += n; argc -= n; } else if (!opts->accept_ref && opts->from_treeish) { diff --git a/t/t7201-co.sh b/t/t7201-co.sh index 9bcf7c0b40..6dfe9ec931 100755 --- a/t/t7201-co.sh +++ b/t/t7201-co.sh @@ -801,4 +801,148 @@ test_expect_success 'tracking info copied with autoSetupMerge=inherit' ' test_cmp_config "" --default "" branch.main2.merge ' +test_expect_success 'setup upstream for --track=fetch tests' ' + git checkout main && + git init fetch_upstream && + test_commit -C fetch_upstream u_main && + git remote add fetch_upstream fetch_upstream && + git fetch fetch_upstream && + git -C fetch_upstream checkout -b fetch_new && + test_commit -C fetch_upstream u_new +' + +test_expect_success 'checkout --track=fetch -b picks up branch created upstream after clone' ' + git checkout main && + test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_new && + git checkout --track=fetch -b local_new fetch_upstream/fetch_new && + test_cmp_rev refs/remotes/fetch_upstream/fetch_new HEAD && + test_cmp_config fetch_upstream branch.local_new.remote && + test_cmp_config refs/heads/fetch_new branch.local_new.merge +' + +test_expect_success 'checkout --track=fetch / leaves other tracking branches untouched' ' + git checkout main && + git -C fetch_upstream checkout -b fetch_target && + test_commit -C fetch_upstream u_target_pre && + git -C fetch_upstream checkout -b fetch_other && + test_commit -C fetch_upstream u_other_pre && + git fetch fetch_upstream && + other_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_other) && + git -C fetch_upstream checkout fetch_target && + test_commit -C fetch_upstream u_target_post && + git -C fetch_upstream checkout fetch_other && + test_commit -C fetch_upstream u_other_post && + git checkout --track=fetch -b local_target fetch_upstream/fetch_target && + test_cmp_rev refs/remotes/fetch_upstream/fetch_target HEAD && + test "$(git rev-parse refs/remotes/fetch_upstream/fetch_other)" = "$other_before" +' + +test_expect_success 'checkout --track=fetch with bare remote name fetches only /HEAD target' ' + git checkout main && + git -C fetch_upstream checkout main && + git remote set-head fetch_upstream main && + git -C fetch_upstream checkout -b fetch_unrelated && + test_commit -C fetch_upstream u_unrelated_pre && + git fetch fetch_upstream fetch_unrelated && + unrelated_before=$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated) && + git -C fetch_upstream checkout main && + test_commit -C fetch_upstream u_main_post && + git -C fetch_upstream checkout fetch_unrelated && + test_commit -C fetch_upstream u_unrelated_post && + git checkout --track=fetch -b local_from_remote fetch_upstream && + test_cmp_rev refs/remotes/fetch_upstream/main HEAD && + test "$(git rev-parse refs/remotes/fetch_upstream/fetch_unrelated)" = "$unrelated_before" +' + +test_expect_success 'checkout --track=fetch aborts and does not create branch when no existing ref' ' + git checkout main && + test_might_fail git branch -D bogus && + test_must_fail git checkout --track=fetch -b bogus fetch_upstream/does_not_exist && + test_must_fail git rev-parse --verify refs/heads/bogus +' + +test_expect_success 'checkout --track=fetch warns and proceeds when fetch fails but ref exists' ' + git checkout main && + git -C fetch_upstream checkout -b fetch_offline && + test_commit -C fetch_upstream u_offline && + git fetch fetch_upstream fetch_offline && + saved_url=$(git config remote.fetch_upstream.url) && + test_when_finished "git config remote.fetch_upstream.url \"$saved_url\"" && + git config remote.fetch_upstream.url ./does-not-exist && + git checkout --track=fetch -b local_offline fetch_upstream/fetch_offline 2>err && + test_grep "failed to fetch" err && + test_cmp_rev refs/remotes/fetch_upstream/fetch_offline HEAD +' + +test_expect_success 'checkout --track=fetch resolves through configured fetch refspec' ' + git checkout main && + git -C fetch_upstream checkout -b fetch_refspec && + test_commit -C fetch_upstream u_refspec && + git fetch fetch_upstream fetch_refspec && + git remote add fetch_custom ./fetch_upstream && + test_when_finished "git remote remove fetch_custom" && + git config --replace-all remote.fetch_custom.fetch \ + "+refs/heads/*:refs/remotes/custom-ns/*" && + git fetch fetch_custom && + test_commit -C fetch_upstream u_refspec_post && + git checkout --track=fetch -b local_refspec custom-ns/fetch_refspec && + test_cmp_rev refs/remotes/custom-ns/fetch_refspec HEAD +' + +test_expect_success 'checkout --track=fetch handles hierarchical remote name' ' + git checkout main && + git -C fetch_upstream checkout -b fetch_hier && + test_commit -C fetch_upstream u_hier && + git remote add nested/remote ./fetch_upstream && + test_when_finished "git remote remove nested/remote" && + git fetch nested/remote fetch_hier && + test_commit -C fetch_upstream u_hier_post && + git checkout --track=fetch -b local_hier nested/remote/fetch_hier && + test_cmp_rev refs/remotes/nested/remote/fetch_hier HEAD +' + +test_expect_success 'checkout --track=inherit,direct is rejected' ' + test_must_fail git checkout --track=inherit,direct -b bad fetch_upstream/fetch_new 2>err && + test_grep "cannot combine" err +' + +test_expect_success 'checkout --track=fetch then --track=direct drops fetch (last-one-wins)' ' + git checkout main && + git -C fetch_upstream checkout -b fetch_lastwin && + test_commit -C fetch_upstream u_lastwin && + test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin && + test_must_fail git checkout --track=fetch --track=direct \ + -b local_lastwin fetch_upstream/fetch_lastwin && + test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_lastwin +' + +test_expect_success 'checkout --track=fetch,inherit fetches and inherits' ' + git checkout main && + git -C fetch_upstream checkout -b fetch_inherit && + test_commit -C fetch_upstream u_inherit && + git fetch fetch_upstream fetch_inherit && + git checkout -b base_inherit fetch_upstream/fetch_inherit && + test_commit -C fetch_upstream u_inherit2 && + git checkout main && + git checkout --track=fetch,inherit -b local_inherit base_inherit && + test_cmp_rev refs/remotes/fetch_upstream/fetch_inherit HEAD && + test_cmp_config fetch_upstream branch.local_inherit.remote && + test_cmp_config refs/heads/fetch_inherit branch.local_inherit.merge +' + +test_expect_success 'checkout --track=bogus reports an error' ' + git checkout main && + test_must_fail git checkout --track=bogus -b bogus_branch fetch_upstream/fetch_new 2>err && + test_grep "expects" err +' + +test_expect_success 'switch --track=fetch -c picks up branch created upstream after clone' ' + git checkout main && + git -C fetch_upstream checkout -b fetch_switch && + test_commit -C fetch_upstream u_switch && + test_must_fail git rev-parse --verify refs/remotes/fetch_upstream/fetch_switch && + git switch --track=fetch -c local_switch fetch_upstream/fetch_switch && + test_cmp_rev refs/remotes/fetch_upstream/fetch_switch HEAD +' + test_done base-commit: 29bd7ed5127255713c1ac2f43b7c6f257d7b4594 -- gitgitgadget