cherry-pick: Suggest a better method to retain authorship
[gitweb.git] / git-checkout.sh
index dd477245fb3703402b950cbc1378b35ce379d631..14835a4aa982af88d758ea014afacf7b2fb1bb1e 100755 (executable)
@@ -1,11 +1,13 @@
 #!/bin/sh
 
-USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
+USAGE='[-q] [-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
 SUBDIRECTORY_OK=Sometimes
 . git-sh-setup
+require_work_tree
 
 old_name=HEAD
 old=$(git-rev-parse --verify $old_name 2>/dev/null)
+oldbranch=$(git-symbolic-ref $old_name 2>/dev/null)
 new=
 new_name=
 force=
@@ -13,6 +15,9 @@ branch=
 newbranch=
 newbranch_log=
 merge=
+quiet=
+LF='
+'
 while [ "$#" != "0" ]; do
     arg="$1"
     shift
@@ -22,7 +27,7 @@ while [ "$#" != "0" ]; do
                shift
                [ -z "$newbranch" ] &&
                        die "git checkout: -b needs a branch name"
-               [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
+               git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
                        die "git checkout: branch $newbranch already exists"
                git-check-ref-format "heads/$newbranch" ||
                        die "git checkout: we do not like '$newbranch' as a branch name."
@@ -36,6 +41,9 @@ while [ "$#" != "0" ]; do
        -m)
                merge=1
                ;;
+       "-q")
+               quiet=1
+               ;;
        --)
                break
                ;;
@@ -50,8 +58,9 @@ while [ "$#" != "0" ]; do
                                exit 1
                        fi
                        new="$rev"
-                       new_name="$arg^0"
-                       if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
+                       new_name="$arg"
+                       if git-show-ref --verify --quiet -- "refs/heads/$arg"
+                       then
                                branch="$arg"
                        fi
                elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
@@ -76,6 +85,11 @@ while [ "$#" != "0" ]; do
     esac
 done
 
+case "$force$merge" in
+11)
+       die "git checkout: -f and -m are incompatible"
+esac
+
 # The behaviour of the command with and without explicit path
 # parameters is quite different.
 #
@@ -106,7 +120,11 @@ Did you intend to checkout '$@' which can not be resolved as commit?"
                git-ls-tree --full-name -r "$new" "$@" |
                git-update-index --index-info || exit $?
        fi
-       git-checkout-index -f -u -- "$@"
+
+       # Make sure the request is about existing paths.
+       git-ls-files --error-unmatch -- "$@" >/dev/null || exit
+       git-ls-files -- "$@" |
+       git-checkout-index -f -u --stdin
        exit $?
 else
        # Make sure we did not fall back on $arg^{tree} codepath
@@ -121,28 +139,43 @@ 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
+cd_to_toplevel
 
 [ -z "$new" ] && new=$old && new_name="$old_name"
 
-# If we don't have an old branch that we're switching to,
+# If we don't have an existing branch that we're switching to,
 # and we don't have a new branch name for the target we
-# are switching to, then we'd better just be checking out
-# what we already had
+# are switching to, then we are detaching our HEAD from any
+# branch.  However, if "git checkout HEAD" detaches the HEAD
+# from the current branch, even though that may be logically
+# correct, it feels somewhat funny.  More importantly, we do not
+# want "git checkout" nor "git checkout -f" to detach HEAD.
+
+detached=
+detach_warn=
 
-[ -z "$branch$newbranch" ] &&
-       [ "$new" != "$old" ] &&
-       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 test -z "$branch$newbranch" && test "$new" != "$old"
+then
+       detached="$new"
+       if test -n "$oldbranch" && test -z "$quiet"
+       then
+               detach_warn="Note: moving to \"$new_name\" which isn't a local branch
+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 "$oldbranch" && test -z "$quiet"
+then
+       echo >&2 "Previous HEAD position was $old"
+fi
 
 if [ "X$old" = X ]
 then
-       echo "warning: You do not appear to currently be on a branch." >&2
-       echo "warning: Forcing checkout of $new_name." >&2
+       if test -z "$quiet"
+       then
+               echo >&2 "warning: You appear to be on a branch yet to be born."
+               echo >&2 "warning: Forcing checkout of $new_name."
+       fi
        force=1
 fi
 
@@ -151,7 +184,7 @@ then
     git-read-tree --reset -u $new
 else
     git-update-index --refresh >/dev/null
-    merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
+    merge_error=$(git-read-tree -m -u --exclude-per-directory=.gitignore $old $new 2>&1) || (
        case "$merge" in
        '')
                echo >&2 "$merge_error"
@@ -161,15 +194,12 @@ else
        # 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 -u $new &&
-       git read-tree -m -u --aggressive $old $new $work || exit
+       git read-tree --reset -u $new || 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
+       eval GITHEAD_$new=${new_name:-${branch:-$new}} &&
+       eval GITHEAD_$work=local &&
+       export GITHEAD_$new GITHEAD_$work &&
+       git merge-recursive $old -- $new $work
 
        # Do not register the cleanly merged paths in the index yet.
        # this is not a real merge before committing, but just carrying
@@ -190,9 +220,9 @@ else
        exit 0
     )
     saved_err=$?
-    if test "$saved_err" = 0
+    if test "$saved_err" = 0 && test -z "$quiet"
     then
-       test "$new" = "$old" || git diff-index --name-status "$new"
+       git diff-index --name-status "$new"
     fi
     (exit $saved_err)
 fi
@@ -212,8 +242,30 @@ if [ "$?" -eq 0 ]; then
                git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
                branch="$newbranch"
        fi
-       [ "$branch" ] &&
-       GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
+       if test -n "$branch"
+       then
+               GIT_DIR="$GIT_DIR" git-symbolic-ref -m "checkout: moving to $branch" HEAD "refs/heads/$branch"
+               if test -z "$quiet"
+               then
+                       echo >&2 "Switched to${newbranch:+ a new} branch \"$branch\""
+               fi
+       elif test -n "$detached"
+       then
+               # NEEDSWORK: we would want a command to detach the HEAD
+               # atomically, instead of this handcrafted command sequence.
+               # Perhaps:
+               #       git update-ref --detach HEAD $new
+               # or something like that...
+               #
+               git-rev-parse HEAD >"$GIT_DIR/HEAD.new" &&
+               mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" &&
+               git-update-ref -m "checkout: moving to $arg" HEAD "$detached" ||
+                       die "Cannot detach HEAD"
+               if test -n "$detach_warn"
+               then
+                       echo >&2 "$detach_warn"
+               fi
+       fi
        rm -f "$GIT_DIR/MERGE_HEAD"
 else
        exit 1