[PATCH v3 1/3] merge: setup `opts` later in `checkout_fast_forward()`

[Martin Ågren]

After we initialize the various fields in `opts` but before we actually
use them, we might return early. Move the initialization further down,
to immediately before we use `opts`.

This limits the scope of `opts` and will help a later commit fix a
memory leak without having to worry about those early returns.

This patch is best viewed using something like this (note the tab!):
--color-moved --anchored="      trees[nr_trees] = parse_tree_indirect"

Signed-off-by: Martin Ågren <martin.ag...@gmail.com>
Signed-off-by: Junio C Hamano <gits...@pobox.com>
---
 merge.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/merge.c b/merge.c
index f06a4773d4..f123658e58 100644
--- a/merge.c
+++ b/merge.c
@@ -94,8 +94,24 @@ int checkout_fast_forward(const struct object_id *head,
                return -1;
 
        memset(&trees, 0, sizeof(trees));
-       memset(&opts, 0, sizeof(opts));
        memset(&t, 0, sizeof(t));
+
+       trees[nr_trees] = parse_tree_indirect(head);
+       if (!trees[nr_trees++]) {
+               rollback_lock_file(&lock_file);
+               return -1;
+       }
+       trees[nr_trees] = parse_tree_indirect(remote);
+       if (!trees[nr_trees++]) {
+               rollback_lock_file(&lock_file);
+               return -1;
+       }
+       for (i = 0; i < nr_trees; i++) {
+               parse_tree(trees[i]);
+               init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
+       }
+
+       memset(&opts, 0, sizeof(opts));
        if (overwrite_ignore) {
                memset(&dir, 0, sizeof(dir));
                dir.flags |= DIR_SHOW_IGNORED;
@@ -112,20 +128,6 @@ int checkout_fast_forward(const struct object_id *head,
        opts.fn = twoway_merge;
        setup_unpack_trees_porcelain(&opts, "merge");
 
-       trees[nr_trees] = parse_tree_indirect(head);
-       if (!trees[nr_trees++]) {
-               rollback_lock_file(&lock_file);
-               return -1;
-       }
-       trees[nr_trees] = parse_tree_indirect(remote);
-       if (!trees[nr_trees++]) {
-               rollback_lock_file(&lock_file);
-               return -1;
-       }
-       for (i = 0; i < nr_trees; i++) {
-               parse_tree(trees[i]);
-               init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
-       }
        if (unpack_trees(nr_trees, t, &opts)) {
                rollback_lock_file(&lock_file);
                return -1;
-- 
2.17.0.840.g5d83f92caf