Re: [PATCH] builtin-commit: fix "git add x y && git commit y" committing x, too

Earlier, builtin commit would implicitly commit also the staged
changes.

This patch fixes that.

Signed-off-by: Johannes Schindelin <redacted>
---

	The function reset_index_to_head() could be moved to somewhere
	more central and be reused in builtin-reset.c instead of
	reset_index_file() later...

 builtin-add.c     |    1 +
 builtin-commit.c  |   30 +++++++++++++++++++++++++++++-
 t/t7500-commit.sh |   10 ++++++++++
 3 files changed, 40 insertions(+), 1 deletions(-)

diff --git a/builtin-add.c b/builtin-add.c
index 77dcde6..017c8f2 100644
--- a/builtin-add.c
+++ b/builtin-add.c

@@ -100,6 +100,7 @@ static void update_callback(struct diff_queue_struct *q,
 		case DIFF_STATUS_UNMERGED:
 		case DIFF_STATUS_MODIFIED:
 		case DIFF_STATUS_TYPE_CHANGED:
+		case DIFF_STATUS_ADDED:
 			add_file_to_cache(path, verbose);
 			break;
 		case DIFF_STATUS_DELETED:

diff --git a/builtin-commit.c b/builtin-commit.c
index 535039c..0dc6e1c 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c

@@ -19,6 +19,7 @@
 #include "strbuf.h"
 #include "utf8.h"
 #include "parse-options.h"
+#include "unpack-trees.h"
 
 static const char * const builtin_commit_usage[] = {
 	"git-commit [options] [--] <filepattern>...",

@@ -77,6 +78,31 @@ static struct option builtin_commit_options[] = {
 	OPT_END()
 };
 
+static int reset_index_to_head(void)
+{
+	struct unpack_trees_options opts;
+	struct tree_desc tree_desc;
+	struct tree *tree;
+	unsigned char sha1[20];
+
+	/* ignore if it is an initial commit */
+	if (get_sha1("HEAD", sha1))
+		return 0;
+	tree = parse_tree_indirect(sha1);
+	if (!tree || parse_tree(tree))
+		return error("Could not get HEAD's tree");
+	init_tree_desc(&tree_desc, tree->buffer, tree->size);
+
+	memset(&opts, 0, sizeof(opts));
+	opts.index_only = 1;
+	opts.merge = 1;
+	opts.head_idx = 1;
+	opts.fn = oneway_merge;
+	if (unpack_trees(1, &tree_desc, &opts))
+		return error("Could not reset temporary index to HEAD");
+	return 0;
+}
+
 static char *prepare_index(const char **files, const char *prefix)
 {
 	int fd;

@@ -120,12 +146,14 @@ static char *prepare_index(const char **files, const char *prefix)
 			die("failed to read HEAD tree object");
 	}
 
+	if (reset_index_to_head())
+		die ("failed to reset temporary index to HEAD");
+