checkout: introduce --detach synonym for "git checkout foo^{commit}"
For example, one might use this when making a temporary merge to test that two topics work well together. Patch by Junio, with tests from Jeff King. [jn: with some extra checks for bogus commandline usage] Suggested-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Junio C Hamano committed
Feb 8, 2011 at 04:32 UTC
32669671c7746888aa1e3832907deb7fc8405061
3 files changed
+126
-7
Documentation/git-checkout.txt
+11
-2
@@ -9,6 +9,7 @@ SYNOPSIS
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--------
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[verse]
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'git checkout' [-q] [-f] [-m] [<branch>]
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+'git checkout' [-q] [-f] [-m] [--detach] [<commit>]
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'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>]
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'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>...
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'git checkout' --patch [<tree-ish>] [--] [<paths>...]
@@ -22,9 +23,10 @@ branch.
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'git checkout' [<branch>]::
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'git checkout' -b|-B <new_branch> [<start point>]::
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+'git checkout' [--detach] [<commit>]::
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This form switches branches by updating the index, working
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- tree, and HEAD to reflect the specified branch.
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+ tree, and HEAD to reflect the specified branch or commit.
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+
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If `-b` is given, a new branch is created as if linkgit:git-branch[1]
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were called and then checked out; in this case you can
@@ -115,6 +117,13 @@ explicitly give a name with '-b' in such a case.
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Create the new branch's reflog; see linkgit:git-branch[1] for
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details.
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+--detach::
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+ Rather than checking out a branch to work on it, check out a
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+ commit for inspection and discardable experiments.
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+ This is the default behavior of "git checkout <commit>" when
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+ <commit> is not a branch name. See the "DETACHED HEAD" section
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+ below for details.
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+
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--orphan::
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Create a new 'orphan' branch, named <new_branch>, started from
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<start_point> and switch to it. The first commit made on this
@@ -204,7 +213,7 @@ leave out at most one of `A` and `B`, in which case it defaults to `HEAD`.
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-Detached HEAD
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+DETACHED HEAD
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-------------
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It is sometimes useful to be able to 'checkout' a commit that is
builtin/checkout.c
+20
-5
@@ -30,6 +30,7 @@ struct checkout_opts {
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int quiet;
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int merge;
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int force;
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+ int force_detach;
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int writeout_stage;
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int writeout_error;
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@@ -563,7 +564,7 @@ static void update_refs_for_switch(struct checkout_opts *opts,
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if (!file_exists(ref_file) && file_exists(log_file))
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remove_path(log_file);
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}
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- } else if (strcmp(new->name, "HEAD")) {
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+ } else if (opts->force_detach || strcmp(new->name, "HEAD")) {
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update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
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REF_NODEREF, DIE_ON_ERR);
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if (!opts->quiet) {
@@ -574,7 +575,8 @@ static void update_refs_for_switch(struct checkout_opts *opts,
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}
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remove_branch_state();
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strbuf_release(&msg);
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- if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
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+ if (!opts->quiet &&
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+ (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
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report_tracking(new);
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}
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@@ -677,6 +679,7 @@ static const char *unique_tracking_name(const char *name)
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static int parse_branchname_arg(int argc, const char **argv,
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int dwim_new_local_branch_ok,
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+ int force_detach,
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struct branch_info *new,
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struct tree **source_tree,
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unsigned char rev[20],
@@ -753,7 +756,8 @@ static int parse_branchname_arg(int argc, const char **argv,
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new->name = arg;
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setup_branch_path(new);
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- if (check_ref_format(new->path) == CHECK_REF_FORMAT_OK &&
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+ if (!force_detach &&
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+ check_ref_format(new->path) == CHECK_REF_FORMAT_OK &&
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resolve_ref(new->path, branch_rev, 1, NULL))
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hashcpy(rev, branch_rev);
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else
@@ -804,6 +808,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
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OPT_STRING('B', NULL, &opts.new_branch_force, "branch",
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"create/reset and checkout a branch"),
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OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "create reflog for new branch"),
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+ OPT_BOOLEAN(0, "detach", &opts.force_detach, "detach the HEAD at named commit"),
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OPT_SET_INT('t', "track", &opts.track, "set upstream info for new branch",
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BRANCH_TRACK_EXPLICIT),
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OPT_STRING(0, "orphan", &opts.new_orphan_branch, "new branch", "new unparented branch"),
@@ -842,9 +847,15 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
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opts.new_branch = opts.new_branch_force;
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if (patch_mode && (opts.track > 0 || opts.new_branch
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- || opts.new_branch_log || opts.merge || opts.force))
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+ || opts.new_branch_log || opts.merge || opts.force
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+ || opts.force_detach))
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die ("--patch is incompatible with all other options");
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+ if (opts.force_detach && (opts.new_branch || opts.new_orphan_branch))
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+ die("--detach cannot be used with -b/-B/--orphan");
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+ if (opts.force_detach && 0 < opts.track)
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+ die("--detach cannot be used with -t");
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+
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/* --track without -b should DWIM */
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if (0 < opts.track && !opts.new_branch) {
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const char *argv0 = argv[0];
@@ -895,7 +906,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
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dwim_new_local_branch &&
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opts.track == BRANCH_TRACK_UNSPECIFIED &&
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!opts.new_branch;
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- int n = parse_branchname_arg(argc, argv, dwim_ok,
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+ int n = parse_branchname_arg(argc, argv,
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+ dwim_ok, opts.force_detach,
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&new, &source_tree, rev, &opts.new_branch);
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argv += n;
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argc -= n;
@@ -922,6 +934,9 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
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}
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}
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+ if (opts.force_detach)
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+ die("git checkout: --detach does not take a path argument");
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+
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if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
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die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
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t/t2020-checkout-detach.sh
new
+95
@@ -0,0 +1,95 @@
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+#!/bin/sh
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+
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+test_description='checkout into detached HEAD state'
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+. ./test-lib.sh
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+
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+check_detached () {
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+ test_must_fail git symbolic-ref -q HEAD >/dev/null
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+}
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+
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+check_not_detached () {
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+ git symbolic-ref -q HEAD >/dev/null
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+}
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+
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+reset () {
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+ git checkout master &&
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+ check_not_detached
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+}
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+
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+test_expect_success 'setup' '
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+ test_commit one &&
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+ test_commit two &&
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+ git branch branch &&
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+ git tag tag
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+'
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+
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+test_expect_success 'checkout branch does not detach' '
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+ reset &&
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+ git checkout branch &&
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+ check_not_detached
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+'
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+
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+test_expect_success 'checkout tag detaches' '
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+ reset &&
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+ git checkout tag &&
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+ check_detached
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+'
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+
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+test_expect_success 'checkout branch by full name detaches' '
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+ reset &&
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+ git checkout refs/heads/branch &&
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+ check_detached
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+'
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+
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+test_expect_success 'checkout non-ref detaches' '
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+ reset &&
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+ git checkout branch^ &&
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+ check_detached
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+'
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+
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+test_expect_success 'checkout ref^0 detaches' '
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+ reset &&
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+ git checkout branch^0 &&
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+ check_detached
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+'
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+
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+test_expect_success 'checkout --detach detaches' '
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+ reset &&
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+ git checkout --detach branch &&
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+ check_detached
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+'
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+
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+test_expect_success 'checkout --detach without branch name' '
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+ reset &&
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+ git checkout --detach &&
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+ check_detached
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+'
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+
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+test_expect_success 'checkout --detach errors out for non-commit' '
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+ reset &&
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+ test_must_fail git checkout --detach one^{tree} &&
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+ check_not_detached
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+'
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+
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+test_expect_success 'checkout --detach errors out for extra argument' '
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+ reset &&
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+ git checkout master &&
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+ test_must_fail git checkout --detach tag one.t &&
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+ check_not_detached
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+'
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+
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+test_expect_success 'checkout --detached and -b are incompatible' '
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+ reset &&
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+ test_must_fail git checkout --detach -b newbranch tag &&
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+ check_not_detached
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+'
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+
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+test_expect_success 'checkout --detach moves HEAD' '
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+ reset &&
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+ git checkout one &&
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+ git checkout --detach two &&
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+ git diff --exit-code HEAD &&
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+ git diff --exit-code two
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+'
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+
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+test_done