The server_status flags are enums in MySQL 8.0

Author: sodabrew

ext/mysql2/client.c

@@ -1589,19 +1589,19 @@ void init_mysql2_client() {
 void rb_mysql_set_server_query_flags(MYSQL *client, VALUE result) {
   VALUE server_flags = rb_hash_new();
 
-#ifdef SERVER_QUERY_NO_GOOD_INDEX_USED
+#ifdef HAVE_CONST_SERVER_QUERY_NO_GOOD_INDEX_USED
   rb_hash_aset(server_flags, sym_no_good_index_used, flag_to_bool(SERVER_QUERY_NO_GOOD_INDEX_USED));
 #else
   rb_hash_aset(server_flags, sym_no_good_index_used, Qnil);
 #endif
 
-#ifdef SERVER_QUERY_NO_INDEX_USED
+#ifdef HAVE_CONST_SERVER_QUERY_NO_INDEX_USED
   rb_hash_aset(server_flags, sym_no_index_used, flag_to_bool(SERVER_QUERY_NO_INDEX_USED));
 #else
   rb_hash_aset(server_flags, sym_no_index_used, Qnil);
 #endif
 
-#ifdef SERVER_QUERY_WAS_SLOW
+#ifdef HAVE_CONST_SERVER_QUERY_WAS_SLOW
   rb_hash_aset(server_flags, sym_query_was_slow, flag_to_bool(SERVER_QUERY_WAS_SLOW));
 #else
   rb_hash_aset(server_flags, sym_query_was_slow, Qnil);

ext/mysql2/extconf.rb

@@ -110,7 +110,11 @@ def add_ssl_defines(header)
 add_ssl_defines(mysql_h)
 have_struct_member('MYSQL', 'net.vio', mysql_h)
 have_struct_member('MYSQL', 'net.pvio', mysql_h)
+# These constants are actually enums, so they cannot be detected by #ifdef in C code.
 have_const('MYSQL_ENABLE_CLEARTEXT_PLUGIN', mysql_h)
+have_const('SERVER_QUERY_NO_GOOD_INDEX_USED', mysql_h)
+have_const('SERVER_QUERY_NO_INDEX_USED', mysql_h)
+have_const('SERVER_QUERY_WAS_SLOW', mysql_h)
 have_const('MYSQL_OPT_CONNECT_ATTR_ADD', mysql_h) # for mysql_options4
 
 # This is our wishlist. We use whichever flags work on the host.