bulk-checkin: fix sign compare warnings

In file bulk-checkin.c, three warnings are emitted by
"-Wsign-compare", two of which are caused by trivial loop iterator
type mismatches.  For the third case, the type of `rsize` from

			ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);

can be changed to size_t as both options of the ternary expression are
unsigned and the signedness of the variable isn't really needed
anywhere.

To prevent `read_result != rsize` making a clash, it is to be noted
that `read_result` is checked not to hold negative values.  Therefore
casting the variable to size_t is a safe operation and enough to
remove the sign-compare warning.

Fix issues accordingly, and remove `DISABLE_SIGN_COMPARE_WARNINGS` to
enable "-Wsign-compare" for the file.

Signed-off-by: Tuomas Ahola <taahol@utu.fi>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bulk-checkin.c

@@ -3,7 +3,6 @@
  */
 
 #define USE_THE_REPOSITORY_VARIABLE
-#define DISABLE_SIGN_COMPARE_WARNINGS
 
 #include "git-compat-util.h"
 #include "bulk-checkin.h"
@@ -56,7 +55,6 @@ static void flush_bulk_checkin_packfile(struct bulk_checkin_packfile *state)
 {
 	unsigned char hash[GIT_MAX_RAWSZ];
 	struct strbuf packname = STRBUF_INIT;
-	int i;
 
 	if (!state->f)
 		return;
@@ -82,7 +80,7 @@ static void flush_bulk_checkin_packfile(struct bulk_checkin_packfile *state)
 	finish_tmp_packfile(&packname, state->pack_tmp_name,
 			    state->written, state->nr_written,
 			    &state->pack_idx_opts, hash);
-	for (i = 0; i < state->nr_written; i++)
+	for (uint32_t i = 0; i < state->nr_written; i++)
 		free(state->written[i]);
 
 clear_exit:
@@ -131,14 +129,12 @@ static void flush_batch_fsync(void)
 
 static int already_written(struct bulk_checkin_packfile *state, struct object_id *oid)
 {
-	int i;
-
 	/* The object may already exist in the repository */
 	if (repo_has_object_file(the_repository, oid))
 		return 1;
 
 	/* Might want to keep the list sorted */
-	for (i = 0; i < state->nr_written; i++)
+	for (uint32_t i = 0; i < state->nr_written; i++)
 		if (oideq(&state->written[i]->oid, oid))
 			return 1;
 
@@ -182,13 +178,13 @@ static int stream_blob_to_pack(struct bulk_checkin_packfile *state,
 
 	while (status != Z_STREAM_END) {
 		if (size && !s.avail_in) {
-			ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
+			size_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 			ssize_t read_result = read_in_full(fd, ibuf, rsize);
 			if (read_result < 0)
 				die_errno("failed to read from '%s'", path);
-			if (read_result != rsize)
-				die("failed to read %d bytes from '%s'",
-				    (int)rsize, path);
+			if ((size_t)read_result != rsize)
+				die("failed to read %u bytes from '%s'",
+				    (unsigned)rsize, path);
 			offset += rsize;
 			if (*already_hashed_to < offset) {
 				size_t hsize = offset - *already_hashed_to;