sha1_name: warning ambiguous refs.

diff --git a/git-checkout.sh b/git-checkout.sh
index 36308d22c6a72b9ad53ced60bd3c70a2e17520b6..463ed2eaff906edaeb0f6d3f8138798e373c6495 100755 (executable)
--- a/git-checkout.sh
+++ b/git-checkout.sh
@@ -1,6 +1,7 @@
 #!/bin/sh
 
-USAGE='[-f] [-b <new_branch>] [<branch>] [<paths>...]'
+USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
+SUBDIRECTORY_OK=Sometimes
 . git-sh-setup
 
 old=$(git-rev-parse HEAD)
@@ -8,6 +9,7 @@ new=
 force=
 branch=
 newbranch=
+merge=
 while [ "$#" != "0" ]; do
     arg="$1"
     shift
@@ -20,11 +22,14 @@ while [ "$#" != "0" ]; do
                [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
                        die "git checkout: branch $newbranch already exists"
                git-check-ref-format "heads/$newbranch" ||
-                       die "we do not like '$newbranch' as a branch name."
+                       die "git checkout: we do not like '$newbranch' as a branch name."
                ;;
        "-f")
                force=1
                ;;
+       -m)
+               merge=1
+               ;;
        --)
                break
                ;;
@@ -70,16 +75,22 @@ done
 
 if test "$#" -ge 1
 then
-       if test '' != "$newbranch$force"
+       hint=
+       if test "$#" -eq 1
+       then
+               hint="
+Did you intend to checkout '$@' which can not be resolved as commit?"
+       fi
+       if test '' != "$newbranch$force$merge"
        then
-               die "updating paths and switching branches or forcing are incompatible."
+               die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
        fi
        if test '' != "$new"
        then
                # from a specific tree-ish; note that this is for
                # rescuing paths and is never meant to remove what
                # is not in the named tree-ish.
-               git-ls-tree -r "$new" "$@" |
+               git-ls-tree --full-name -r "$new" "$@" |
                git-update-index --index-info || exit $?
        fi
        git-checkout-index -f -u -- "$@"
@@ -95,6 +106,14 @@ else
        fi
 fi
 
+# We are switching branches and checking out trees, so
+# we *NEED* to be at the toplevel.
+cdup=$(git-rev-parse --show-cdup)
+if test ! -z "$cdup"
+then
+       cd "$cdup"
+fi
+
 [ -z "$new" ] && new=$old
 
 # If we don't have an old branch that we're switching to,
@@ -104,7 +123,8 @@ fi
 
 [ -z "$branch$newbranch" ] &&
        [ "$new" != "$old" ] &&
-       die "git checkout: you need to specify a new branch name"
+       die "git checkout: to checkout the requested commit you need to specify 
+              a name for a new branch which is created and switched to"
 
 if [ "$force" ]
 then
@@ -112,7 +132,51 @@ then
        git-checkout-index -q -f -u -a
 else
     git-update-index --refresh >/dev/null
-    git-read-tree -m -u $old $new
+    merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
+       case "$merge" in
+       '')
+               echo >&2 "$merge_error"
+               exit 1 ;;
+       esac
+
+       # Match the index to the working tree, and do a three-way.
+       git diff-files --name-only | git update-index --remove --stdin &&
+       work=`git write-tree` &&
+       git read-tree --reset $new &&
+       git checkout-index -f -u -q -a &&
+       git read-tree -m -u $old $new $work || exit
+
+       if result=`git write-tree 2>/dev/null`
+       then
+           echo >&2 "Trivially automerged."
+       else
+           git merge-index -o git-merge-one-file -a
+       fi
+
+       # Do not register the cleanly merged paths in the index yet.
+       # this is not a real merge before committing, but just carrying
+       # the working tree changes along.
+       unmerged=`git ls-files -u`
+       git read-tree --reset $new
+       case "$unmerged" in
+       '')     ;;
+       *)
+               (
+                       z40=0000000000000000000000000000000000000000
+                       echo "$unmerged" |
+                       sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
+                       echo "$unmerged"
+               ) | git update-index --index-info
+               ;;
+       esac
+       exit 0
+    )
+    saved_err=$?
+    if test "$saved_err" = 0
+    then
+       test "$new" = "$old" || git diff-index --name-status "$new"
+    fi
+    (exit $saved_err)
 fi
 
 #