git-merge-ours: make it a builtin.

Except that this fixes a longstanding corner case bug by
tightening the way underlying diff-index command is run, it is
functionally equivalent to the scripted version.

Signed-off-by: Thomas Harning Jr <harningt@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -221,7 +221,7 @@ SCRIPT_SH = \
 	git-sh-setup.sh \
 	git-am.sh \
 	git-merge.sh git-merge-stupid.sh git-merge-octopus.sh \
-	git-merge-resolve.sh git-merge-ours.sh \
+	git-merge-resolve.sh \
 	git-lost-found.sh git-quiltimport.sh git-submodule.sh \
 	git-filter-branch.sh \
 	git-stash.sh
@@ -353,6 +353,7 @@ BUILTIN_OBJS = \
 	builtin-mailsplit.o \
 	builtin-merge-base.o \
 	builtin-merge-file.o \
+	builtin-merge-ours.o \
 	builtin-mv.o \
 	builtin-name-rev.o \
 	builtin-pack-objects.o \

builtin-merge-ours.c

@@ -0,0 +1,28 @@
+/*
+ * Implementation of git-merge-ours.sh as builtin
+ *
+ * Copyright (c) 2007 Thomas Harning Jr
+ * Original:
+ * Original Copyright (c) 2005 Junio C Hamano
+ *
+ * Pretend we resolved the heads, but declare our tree trumps everybody else.
+ */
+#include "git-compat-util.h"
+#include "builtin.h"
+
+static const char *diff_index_args[] = {
+	"diff-index", "--quiet", "--cached", "HEAD", "--", NULL
+};
+#define NARGS (ARRAY_SIZE(diff_index_args) - 1)
+
+int cmd_merge_ours(int argc, const char **argv, const char *prefix)
+{
+	/*
+	 * We need to exit with 2 if the index does not match our HEAD tree,
+	 * because the current index is what we will be committing as the
+	 * merge result.
+	 */
+	if (cmd_diff_index(NARGS, diff_index_args, prefix))
+		exit(2);
+	exit(0);
+}

builtin.h

@@ -51,6 +51,7 @@ extern int cmd_ls_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_mailinfo(int argc, const char **argv, const char *prefix);
 extern int cmd_mailsplit(int argc, const char **argv, const char *prefix);
 extern int cmd_merge_base(int argc, const char **argv, const char *prefix);
+extern int cmd_merge_ours(int argc, const char **argv, const char *prefix);
 extern int cmd_merge_file(int argc, const char **argv, const char *prefix);
 extern int cmd_mv(int argc, const char **argv, const char *prefix);
 extern int cmd_name_rev(int argc, const char **argv, const char *prefix);

git.c

@@ -325,6 +325,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "mailsplit", cmd_mailsplit },
 		{ "merge-base", cmd_merge_base, RUN_SETUP },
 		{ "merge-file", cmd_merge_file },
+		{ "merge-ours", cmd_merge_ours, RUN_SETUP },
 		{ "mv", cmd_mv, RUN_SETUP | NEED_WORK_TREE },
 		{ "name-rev", cmd_name_rev, RUN_SETUP },
 		{ "pack-objects", cmd_pack_objects, RUN_SETUP },