checkout: allow detaching to HEAD even when switching to the tip of a branch

You cannot currently checkout the tip of an existing branch
without moving to the branch.

This allows you to detach your HEAD and place it at such a
commit, with:

    $ git checkout master^0

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/git-checkout.sh b/git-checkout.sh
index a7390e808c76dd5c8dab04396974ee5a709497fd..deb0a9a3c733ed889158d05b7cae4d174917553d 100755 (executable)
--- a/git-checkout.sh
+++ b/git-checkout.sh
@@ -170,7 +170,7 @@ describe_detached_head () {
        }
 }
 
-if test -z "$branch$newbranch" && test "$new" != "$old"
+if test -z "$branch$newbranch" && test "$new_name" != "$old_name"
 then
        detached="$new"
        if test -n "$oldbranch" && test -z "$quiet"
@@ -180,7 +180,7 @@ If you want to create a new branch from this checkout, you may do so
 (now or later) by using -b with the checkout command again. Example:
   git checkout -b <new_branch_name>"
        fi
-elif test -z "$oldbranch"
+elif test -z "$oldbranch" && test "$new" != "$old"
 then
        describe_detached_head 'Previous HEAD position was' "$old"
 fi

diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 867bbd26cbbacbe03ef76cadb6ff34976c324da5..5fa6a45577894e05446351fc5076a27accb1fa9f 100755 (executable)
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -3,7 +3,20 @@
 # Copyright (c) 2006 Junio C Hamano
 #
 
-test_description='git-checkout tests.'
+test_description='git-checkout tests.
+
+Creates master, forks renamer and side branches from it.
+Test switching across them.
+
+  ! [master] Initial A one, A two
+   * [renamer] Renamer R one->uno, M two
+    ! [side] Side M one, D two, A three
+  ---
+    + [side] Side M one, D two, A three
+   *  [renamer] Renamer R one->uno, M two
+  +*+ [master] Initial A one, A two
+
+'
 
 . ./test-lib.sh
 
@@ -129,4 +142,52 @@ test_expect_success 'checkout -m with merge conflict' '
        ! test -s current
 '
 
+test_expect_success 'checkout to detach HEAD' '
+
+       git checkout -f renamer && git clean &&
+       git checkout renamer^ &&
+       H=$(git rev-parse --verify HEAD) &&
+       M=$(git show-ref -s --verify refs/heads/master) &&
+       test "z$H" = "z$M" &&
+       if git symbolic-ref HEAD >/dev/null 2>&1
+       then
+               echo "OOPS, HEAD is still symbolic???"
+               false
+       else
+               : happy
+       fi
+'
+
+test_expect_success 'checkout to detach HEAD with branchname^' '
+
+       git checkout -f master && git clean &&
+       git checkout renamer^ &&
+       H=$(git rev-parse --verify HEAD) &&
+       M=$(git show-ref -s --verify refs/heads/master) &&
+       test "z$H" = "z$M" &&
+       if git symbolic-ref HEAD >/dev/null 2>&1
+       then
+               echo "OOPS, HEAD is still symbolic???"
+               false
+       else
+               : happy
+       fi
+'
+
+test_expect_success 'checkout to detach HEAD with HEAD^0' '
+
+       git checkout -f master && git clean &&
+       git checkout HEAD^0 &&
+       H=$(git rev-parse --verify HEAD) &&
+       M=$(git show-ref -s --verify refs/heads/master) &&
+       test "z$H" = "z$M" &&
+       if git symbolic-ref HEAD >/dev/null 2>&1
+       then
+               echo "OOPS, HEAD is still symbolic???"
+               false
+       else
+               : happy
+       fi
+'
+
 test_done