Teach git-stash to "apply --index"

When given this subcommand, git-stash will try to merge the stashed
index into the current one. Only trivial merges are possible, since
we have no index for the index ;-) If a trivial merge is not possible,
git-stash will bail out with a hint to skip the --index option.

For good measure, finally include a test case.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/git-stash.sh b/git-stash.sh
index f01494dc1b..5c63ca5bce 100755
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -111,6 +111,13 @@ apply_stash () {
 	git diff-files --quiet ||
 		die 'Cannot restore on top of a dirty state'
 
+	unstash_index=
+	case "$1" in
+	--index)
+		unstash_index=t
+		shift
+	esac
+
 	# current index state
 	c_tree=$(git write-tree) ||
 		die 'Cannot apply a stash in the middle of a merge'
@@ -120,6 +127,15 @@ apply_stash () {
 	b_tree=$(git rev-parse --verify "$s^:") ||
 		die "$*: no valid stashed state found"
 
+	test -z "$unstash_index" || {
+		git diff --binary $s^2^..$s^2 | git apply --cached
+		test $? -ne 0 &&
+			die 'Conflicts in index. Try without --index.'
+		unstashed_index_tree=$(git-write-tree) ||
+			die 'Could not save index tree'
+		git reset
+	}
+
 	eval "
 		GITHEAD_$w_tree='Stashed changes' &&
 		GITHEAD_$c_tree='Updated upstream' &&
@@ -137,9 +153,12 @@ apply_stash () {
 			die "Cannot unstage modified files"
 		git-status
 		rm -f "$a"
+		test -z "$unstash_index" || git read-tree $unstashed_index_tree
 	else
 		# Merge conflict; keep the exit status from merge-recursive
-		exit
+		status=$?
+		test -z "$unstash_index" || echo 'Index was not unstashed.' >&2
+		exit $status
 	fi
 }