xap_helper: fix C++-specific warnings

While initialization of zeroed structs in C is done via `{0}',
I've just learned from g++(1) that C++ uses `{}'.  I can't seem
to get use of a single designated initializer to compile without
warnings in C++, either, so we'll just initialize them as zero
and assign them ASAP for __cleanup__ functions.

This fixes compilation warnings under -Wextra in g++ (Debian 10.2.1-6)
which adds -Wmissing-field-initializers.  This also fixes compilation
warnings under -Wall in clang (FreeBSD 13.0.0) from -Wmissing.

1 files changed, 7 insertions, 5 deletions

diff --git a/lib/PublicInbox/xap_helper.h b/lib/PublicInbox/xap_helper.h
index e3ccfd41..e10527d1 100644
--- a/lib/PublicInbox/xap_helper.h
+++ b/lib/PublicInbox/xap_helper.h
@@ -436,7 +436,7 @@ static enum exc_iter dump_roots_iter(struct req *req,
                                 struct dump_roots_tmp *drt,
                                 Xapian::MSetIterator *i)
 {
-        CLEANUP_FBUF struct fbuf root_ids = { 0 }; // " $ID0 $ID1 $IDx..\n"
+        CLEANUP_FBUF struct fbuf root_ids = {}; // " $ID0 $ID1 $IDx..\n"
         try {
                 Xapian::Document doc = i->get_document();
                 if (!root2ids_str(&root_ids, &doc))
@@ -453,7 +453,8 @@ static enum exc_iter dump_roots_iter(struct req *req,
 
 static bool cmd_dump_roots(struct req *req)
 {
-        CLEANUP_DUMP_ROOTS struct dump_roots_tmp drt = { .root2id_fd = -1 };
+        CLEANUP_DUMP_ROOTS struct dump_roots_tmp drt = {};
+        drt.root2id_fd = -1;
         if ((optind + 1) >= req->argc) {
                 warnx("usage: dump_roots [OPTIONS] ROOT2ID_FILE QRY_STR");
                 return false; // need file + qry_str
@@ -563,12 +564,13 @@ union my_cmsg {
 
 static bool recv_req(struct req *req, char *rbuf, size_t *len)
 {
-        union my_cmsg cmsg = { 0 };
-        struct msghdr msg = { .msg_iovlen = 1 };
+        union my_cmsg cmsg = {};
+        struct msghdr msg = {};
         struct iovec iov;
         iov.iov_base = rbuf;
         iov.iov_len = *len;
         msg.msg_iov = &iov;
+        msg.msg_iovlen = 1;
         msg.msg_control = &cmsg.hdr;
         msg.msg_controllen = CMSG_SPACE(RECV_FD_SPACE);
 
@@ -823,7 +825,7 @@ static void recv_loop(void) // worker process loop
         static char rbuf[4096 * 33]; // per-process
         while (!parent_pid || getppid() == parent_pid) {
                 size_t len = sizeof(rbuf);
-                struct req req = { 0 };
+                struct req req = {};
                 if (!recv_req(&req, rbuf, &len))
                         continue;
                 if (req.fp[1]) {