builtin/checkout: learn -B

Internally, --track and --orphan still use the 'safe' -b, not -B.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 261dd90c381eccbd87d73325478e1d5abcf05e15..97c51449f76af11f4eab55dc466aacbe79211134 100644 (file)
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -9,7 +9,7 @@ SYNOPSIS
 --------
 [verse]
 'git checkout' [-q] [-f] [-m] [<branch>]
 --------
 [verse]
 'git checkout' [-q] [-f] [-m] [<branch>]

-'git checkout' [-q] [-f] [-m] [[-b|--orphan] <new_branch>] [<start_point>]
+'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>]

 'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
 'git checkout' --patch [<tree-ish>] [--] [<paths>...]
 
 'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
 'git checkout' --patch [<tree-ish>] [--] [<paths>...]
 


@@ -21,7 +21,7 @@ also update `HEAD` to set the specified branch as the current
 branch.
 
 'git checkout' [<branch>]::
 branch.
 
 'git checkout' [<branch>]::

-'git checkout' -b <new branch> [<start point>]::
+'git checkout' -b|-B <new_branch> [<start point>]::

 
        This form switches branches by updating the index, working
        tree, and HEAD to reflect the specified branch.
 
        This form switches branches by updating the index, working
        tree, and HEAD to reflect the specified branch.


@@ -31,6 +31,17 @@ were called and then checked out; in this case you can
 use the `--track` or `--no-track` options, which will be passed to
 'git branch'.  As a convenience, `--track` without `-b` implies branch
 creation; see the description of `--track` below.
 use the `--track` or `--no-track` options, which will be passed to
 'git branch'.  As a convenience, `--track` without `-b` implies branch
 creation; see the description of `--track` below.

++
+If `-B` is given, <new_branch> is created if it doesn't exist; otherwise, it
+is reset. This is the transactional equivalent of
++
+------------
+$ git branch -f <branch> [<start point>]
+$ git checkout <branch>
+------------
++
+that is to say, the branch is not reset/created unless "git checkout" is
+successful.

 
 'git checkout' [--patch] [<tree-ish>] [--] <pathspec>...::
 
 
 'git checkout' [--patch] [<tree-ish>] [--] <pathspec>...::
 


@@ -75,6 +86,12 @@ entries; instead, unmerged entries are ignored.
        Create a new branch named <new_branch> and start it at
        <start_point>; see linkgit:git-branch[1] for details.
 
        Create a new branch named <new_branch> and start it at
        <start_point>; see linkgit:git-branch[1] for details.
 

+-B::
+       Creates the branch <new_branch> and start it at <start_point>;
+       if it already exists, then reset it to <start_point>. This is
+       equivalent to running "git branch" with "-f"; see
+       linkgit:git-branch[1] for details.
+

 -t::
 --track::
        When creating a new branch, set up "upstream" configuration. See
 -t::
 --track::
        When creating a new branch, set up "upstream" configuration. See

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 27e810b15a45a27685b0c16c00d78f70928ca3d0..4ad74270cf1ae8be73372f8511f21ed1b14efdb4 100644 (file)
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -32,7 +32,11 @@ struct checkout_opts {
        int writeout_stage;
        int writeout_error;
 
        int writeout_stage;
        int writeout_error;
 

+       /* not set by parse_options */
+       int branch_exists;
+

        const char *new_branch;
        const char *new_branch;

+       const char *new_branch_force;

        const char *new_orphan_branch;
        int new_branch_log;
        enum branch_track track;
        const char *new_orphan_branch;
        int new_branch_log;
        enum branch_track track;


@@ -511,7 +515,8 @@ static void update_refs_for_switch(struct checkout_opts *opts,
                        }
                }
                else
                        }
                }
                else

-                       create_branch(old->name, opts->new_branch, new->name, 0,
+                       create_branch(old->name, opts->new_branch, new->name,
+                                     opts->new_branch_force ? 1 : 0,

                                      opts->new_branch_log, opts->track);
                new->name = opts->new_branch;
                setup_branch_path(new);
                                      opts->new_branch_log, opts->track);
                new->name = opts->new_branch;
                setup_branch_path(new);


@@ -531,7 +536,7 @@ static void update_refs_for_switch(struct checkout_opts *opts,
                                        new->name);
                        else
                                fprintf(stderr, "Switched to%s branch '%s'\n",
                                        new->name);
                        else
                                fprintf(stderr, "Switched to%s branch '%s'\n",

-                                       opts->new_branch ? " a new" : "",
+                                       opts->branch_exists ? " and reset" : " a new",

                                        new->name);
                }
                if (old->path && old->name) {
                                        new->name);
                }
                if (old->path && old->name) {


@@ -659,6 +664,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
                OPT__QUIET(&opts.quiet),
                OPT_STRING('b', NULL, &opts.new_branch, "branch",
                           "create and checkout a new branch"),
                OPT__QUIET(&opts.quiet),
                OPT_STRING('b', NULL, &opts.new_branch, "branch",
                           "create and checkout a new branch"),

+               OPT_STRING('B', NULL, &opts.new_branch_force, "branch",
+                          "create/reset and checkout a branch"),

                OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
                OPT_SET_INT('t', "track",  &opts.track, "track",
                        BRANCH_TRACK_EXPLICIT),
                OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
                OPT_SET_INT('t', "track",  &opts.track, "track",
                        BRANCH_TRACK_EXPLICIT),


@@ -689,6 +696,14 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
        argc = parse_options(argc, argv, prefix, options, checkout_usage,
                             PARSE_OPT_KEEP_DASHDASH);
 
        argc = parse_options(argc, argv, prefix, options, checkout_usage,
                             PARSE_OPT_KEEP_DASHDASH);
 

+       /* we can assume from now on new_branch = !new_branch_force */
+       if (opts.new_branch && opts.new_branch_force)
+               die("-B cannot be used with -b");
+
+       /* copy -B over to -b, so that we can just check the latter */
+       if (opts.new_branch_force)
+               opts.new_branch = opts.new_branch_force;
+

        if (patch_mode && (opts.track > 0 || opts.new_branch
                           || opts.new_branch_log || opts.merge || opts.force))
                die ("--patch is incompatible with all other options");
        if (patch_mode && (opts.track > 0 || opts.new_branch
                           || opts.new_branch_log || opts.merge || opts.force))
                die ("--patch is incompatible with all other options");


@@ -710,7 +725,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 
        if (opts.new_orphan_branch) {
                if (opts.new_branch)
 
        if (opts.new_orphan_branch) {
                if (opts.new_branch)

-                       die("--orphan and -b are mutually exclusive");
+                       die("--orphan and -b|-B are mutually exclusive");

                if (opts.track > 0)
                        die("--orphan cannot be used with -t");
                opts.new_branch = opts.new_orphan_branch;
                if (opts.track > 0)
                        die("--orphan cannot be used with -t");
                opts.new_branch = opts.new_orphan_branch;


@@ -859,8 +874,12 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
                if (strbuf_check_branch_ref(&buf, opts.new_branch))
                        die("git checkout: we do not like '%s' as a branch name.",
                            opts.new_branch);
                if (strbuf_check_branch_ref(&buf, opts.new_branch))
                        die("git checkout: we do not like '%s' as a branch name.",
                            opts.new_branch);

-               if (!get_sha1(buf.buf, rev))
-                       die("git checkout: branch %s already exists", opts.new_branch);
+               if (!get_sha1(buf.buf, rev)) {
+                       opts.branch_exists = 1;
+                       if (!opts.new_branch_force)
+                               die("git checkout: branch %s already exists",
+                                   opts.new_branch);
+               }

                strbuf_release(&buf);
        }
 
                strbuf_release(&buf);
        }
 

diff --git a/t/t2018-checkout-branch.sh b/t/t2018-checkout-branch.sh
index 3c130659d6506685ba7eee68810f3b6b693c0fed..1caffeac074ed9a8e434a3d6e53c20b00e8672cc 100755 (executable)
--- a/t/t2018-checkout-branch.sh
+++ b/t/t2018-checkout-branch.sh
@@ -118,4 +118,49 @@ test_expect_success 'checkout -b to an existing branch fails' '
        test_must_fail do_checkout branch2 $HEAD2
 '
 
        test_must_fail do_checkout branch2 $HEAD2
 '
 

+test_expect_success 'checkout -B to an existing branch resets branch to HEAD' '
+       git checkout branch1 &&
+
+       do_checkout branch2 "" -B
+'
+
+test_expect_success 'checkout -B to an existing branch with an explicit ref resets branch to that ref' '
+       git checkout branch1 &&
+
+       do_checkout branch2 $HEAD1 -B
+'
+
+test_expect_success 'checkout -B to an existing branch with unmergeable changes fails' '
+       git checkout branch1 &&
+
+       setup_dirty_unmergeable &&
+       test_must_fail do_checkout branch2 $HEAD1 -B &&
+       test_dirty_unmergeable
+'
+
+test_expect_success 'checkout -f -B to an existing branch with unmergeable changes discards changes' '
+       # still dirty and on branch1
+       do_checkout branch2 $HEAD1 "-f -B" &&
+       test_must_fail test_dirty_unmergeable
+'
+
+test_expect_success 'checkout -B to an existing branch preserves mergeable changes' '
+       git checkout branch1 &&
+
+       setup_dirty_mergeable &&
+       do_checkout branch2 $HEAD1 -B &&
+       test_dirty_mergeable
+'
+
+test_expect_success 'checkout -f -B to an existing branch with mergeable changes discards changes' '
+       # clean up from previous test
+       git reset --hard &&
+
+       git checkout branch1 &&
+
+       setup_dirty_mergeable &&
+       do_checkout branch2 $HEAD1 "-f -B" &&
+       test_must_fail test_dirty_mergeable
+'
+

 test_done
 test_done