bulk-checkin: zero-initialize hashfile_checkpoint

We declare a "struct hashfile_checkpoint" but only sometimes actually
call hashfile_checkpoint() on it. That makes it not immediately obvious
that it's valid when we later access its members.

In fact, the code is fine: we fill it in unconditionally in the while(1)
loop as long as "idx" is non-NULL. And then if "idx" is NULL, we exit
early from the function (because we're just computing the hash, not
actually writing), before we look at the struct.

However, this does seem to confuse gcc 9.2.1's -Wmaybe-uninitialized
when compiled with "-flto -O2" (probably because with LTO it can now
realize that our call to hashfile_truncate() does not set the members
either). Let's zero-initialize the struct to tell the compiler, as well
as any readers of the code, that all is well.

Reported-by: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/bulk-checkin.c b/bulk-checkin.c
index 39ee7d6107c15f3e5e439992bea8a8f3413aae05..583aacb9e36bded9047d5f18219637ba1613a612 100644 (file)
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -197,7 +197,7 @@ static int deflate_to_pack(struct bulk_checkin_state *state,
        git_hash_ctx ctx;
        unsigned char obuf[16384];
        unsigned header_len;
        git_hash_ctx ctx;
        unsigned char obuf[16384];
        unsigned header_len;

-       struct hashfile_checkpoint checkpoint;
+       struct hashfile_checkpoint checkpoint = {0};

        struct pack_idx_entry *idx = NULL;
 
        seekback = lseek(fd, 0, SEEK_CUR);
        struct pack_idx_entry *idx = NULL;
 
        seekback = lseek(fd, 0, SEEK_CUR);