constness fixes

add missing const qualifications, and add "const cast" suppressions
where unavoidable.

src/drv_maildir.c

@@ -649,7 +649,10 @@ static void
 make_key( const char *info_stop, DBT *tkey, const char *name )
 {
 	char *u = strpbrk( name, info_stop );
+DIAG_PUSH
+DIAG_DISABLE("-Wcast-qual")  // C has no const_cast<> ...
 	tkey->data = (char *)name;
+DIAG_POP
 	tkey->size = u ? (size_t)(u - name) : strlen( name );
 }
 #endif /* USE_DB */
@@ -844,7 +847,7 @@ maildir_set_uid( maildir_store_t *ctx, const char *name, uint *uid )
 static int
 maildir_compare( const void *l, const void *r )
 {
-	msg_t *lm = (msg_t *)l, *rm = (msg_t *)r;
+	const msg_t *lm = (const msg_t *)l, *rm = (const msg_t *)r;
 	char *ldot, *rdot, *ldot2, *rdot2, *lseq, *rseq;
 	int ret, llen, rlen;
 

src/main.c

@@ -248,8 +248,8 @@ is_inbox( const char *name )
 static int
 cmp_box_names( const void *a, const void *b )
 {
-	const char *as = *(const char **)a;
-	const char *bs = *(const char **)b;
+	const char *as = *(const char * const *)a;
+	const char *bs = *(const char * const *)b;
 	int ai = is_inbox( as );
 	int bi = is_inbox( bs );
 	int di = bi - ai;
@@ -1087,14 +1087,14 @@ sync_listed_boxes( main_vars_t *mvars, box_ent_t *mbox )
 		if (!mvars->list) {
 			nfasprintf( &mvars->names[M], "%s%s", mpfx, mbox->name );
 			nfasprintf( &mvars->names[S], "%s%s", spfx, mbox->name );
-			sync_boxes( mvars->ctx, (const char **)mvars->names, mbox->present, mvars->chan, done_sync_2_dyn, mvars );
+			sync_boxes( mvars->ctx, (const char * const *)mvars->names, mbox->present, mvars->chan, done_sync_2_dyn, mvars );
 			return 1;
 		}
 		printf( "%s%s <=> %s%s\n", mpfx, mbox->name, spfx, mbox->name );
 	} else {
 		if (!mvars->list) {
 			mvars->names[M] = mvars->names[S] = mbox->name;
-			sync_boxes( mvars->ctx, (const char **)mvars->names, mbox->present, mvars->chan, done_sync, mvars );
+			sync_boxes( mvars->ctx, (const char * const *)mvars->names, mbox->present, mvars->chan, done_sync, mvars );
 			return 1;
 		}
 		puts( mbox->name );

src/socket.c

@@ -232,7 +232,10 @@ verify_cert_host( const server_conf_t *conf, conn_t *sock )
 static int
 init_ssl_ctx( const server_conf_t *conf )
 {
+DIAG_PUSH
+DIAG_DISABLE("-Wcast-qual")  // C has no 'mutable' or const_cast<> ...
 	server_conf_t *mconf = (server_conf_t *)conf;
+DIAG_POP
 
 	if (conf->SSLContext)
 		return conf->ssl_ctx_valid;
@@ -320,7 +323,7 @@ socket_start_tls( conn_t *conn, void (*cb)( int ok, void *aux ) )
 	}
 
 	init_wakeup( &conn->ssl_fake, ssl_fake_cb, conn );
-	if (!(conn->ssl = SSL_new( ((server_conf_t *)conn->conf)->SSLContext ))) {
+	if (!(conn->ssl = SSL_new( ((server_conf_t const *)conn->conf)->SSLContext ))) {
 		print_ssl_errors( "initializing SSL connection" );
 		start_tls_p3( conn, 0 );
 		return;

src/sync.c

@@ -1002,7 +1002,7 @@ static void box_opened2( sync_vars_t *svars, int t );
 static void load_box( sync_vars_t *svars, int t, uint minwuid, uint_array_t mexcs );
 
 void
-sync_boxes( store_t *ctx[], const char *names[], int present[], channel_conf_t *chan,
+sync_boxes( store_t *ctx[], const char * const names[], int present[], channel_conf_t *chan,
             void (*cb)( int sts, void *aux ), void *aux )
 {
 	sync_vars_t *svars;

src/sync.h

@@ -80,7 +80,7 @@ extern const char *str_ms[2], *str_hl[2];
 #define BOX_PRESENT   1
 
 /* All passed pointers must stay alive until cb is called. */
-void sync_boxes( store_t *ctx[], const char *names[], int present[], channel_conf_t *chan,
+void sync_boxes( store_t *ctx[], const char * const names[], int present[], channel_conf_t *chan,
                  void (*cb)( int sts, void *aux ), void *aux );
 
 #endif

src/util.c

@@ -541,7 +541,7 @@ map_name( const char *arg, char **result, int reserve, const char *in, const cha
 static int
 compare_uints( const void *l, const void *r )
 {
-	uint li = *(uint *)l, ri = *(uint *)r;
+	uint li = *(const uint *)l, ri = *(const uint *)r;
 	if (li != ri)  // Can't subtract, the result might not fit into signed int.
 		return li > ri ? 1 : -1;
 	return 0;