reftable/block: introduce macro to initialize struct block_iter

There are a bunch of locations where we initialize members of `struct
block_iter`, which makes it harder than necessary to expand this struct
to have additional members. Unify the logic via a new `BLOCK_ITER_INIT`
macro that initializes all members.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

reftable/block.c

@@ -389,9 +389,7 @@ int block_reader_seek(struct block_reader *br, struct block_iter *it,
 	struct reftable_record rec = reftable_new_record(block_reader_type(br));
 	struct strbuf key = STRBUF_INIT;
 	int err = 0;
-	struct block_iter next = {
-		.last_key = STRBUF_INIT,
-	};
+	struct block_iter next = BLOCK_ITER_INIT;
 
 	int i = binsearch(br->restart_count, &restart_key_less, &args);
 	if (args.error) {

reftable/block.h

@@ -86,6 +86,10 @@ struct block_iter {
 	struct strbuf last_key;
 };
 
+#define BLOCK_ITER_INIT { \
+	.last_key = STRBUF_INIT, \
+}
+
 /* initializes a block reader. */
 int block_reader_init(struct block_reader *br, struct reftable_block *bl,
 		      uint32_t header_off, uint32_t table_block_size,

reftable/block_test.c

@@ -32,7 +32,7 @@ static void test_block_read_write(void)
 	int i = 0;
 	int n;
 	struct block_reader br = { 0 };
-	struct block_iter it = { .last_key = STRBUF_INIT };
+	struct block_iter it = BLOCK_ITER_INIT;
 	int j = 0;
 	struct strbuf want = STRBUF_INIT;
 
@@ -87,7 +87,7 @@ static void test_block_read_write(void)
 	block_iter_close(&it);
 
 	for (i = 0; i < N; i++) {
-		struct block_iter it = { .last_key = STRBUF_INIT };
+		struct block_iter it = BLOCK_ITER_INIT;
 		strbuf_reset(&want);
 		strbuf_addstr(&want, names[i]);
 

reftable/iter.h

@@ -53,10 +53,10 @@ struct indexed_table_ref_iter {
 	int is_finished;
 };
 
-#define INDEXED_TABLE_REF_ITER_INIT                                     \
-	{                                                               \
-		.cur = { .last_key = STRBUF_INIT }, .oid = STRBUF_INIT, \
-	}
+#define INDEXED_TABLE_REF_ITER_INIT { \
+	.cur = BLOCK_ITER_INIT, \
+	.oid = STRBUF_INIT, \
+}
 
 void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it,
 					  struct indexed_table_ref_iter *itr);

reftable/reader.c

@@ -224,10 +224,9 @@ struct table_iter {
 	struct block_iter bi;
 	int is_finished;
 };
-#define TABLE_ITER_INIT                          \
-	{                                        \
-		.bi = {.last_key = STRBUF_INIT } \
-	}
+#define TABLE_ITER_INIT { \
+	.bi = BLOCK_ITER_INIT \
+}
 
 static void table_iter_copy_from(struct table_iter *dest,
 				 struct table_iter *src)