MDEV-26831 fallout: name resolution cache simple test

mysql-test/main/name_resolution_cache_debug.result

+connect con1,localhost,root;
+create table t1 (a int, b int);
+create table t2 (c int, d int);
+create view v1 as select c+1 as e, d+1 as f from t2;
+SET DEBUG_SYNC= 'table_field_cached SIGNAL in_sync WAIT_FOR go';
+prepare stmt1 from "select a from t1";
+execute stmt1;
+connection default;
+SET DEBUG_SYNC= 'now WAIT_FOR in_sync';
+SET DEBUG_SYNC= 'now SIGNAL go';
+connection con1;
+a
+SET DEBUG_SYNC= 'table_field_cached SIGNAL in_sync WAIT_FOR go';
+prepare stmt1 from "select e from v1";
+execute stmt1;
+connection default;
+SET DEBUG_SYNC= 'now WAIT_FOR in_sync';
+SET DEBUG_SYNC= 'now SIGNAL go';
+connection con1;
+e
+connection default;
+disconnect con1;
+SET DEBUG_SYNC = 'RESET';
+drop view v1;
+drop table t1,t2;

mysql-test/main/name_resolution_cache_debug.test

+
+source include/have_debug_sync.inc;
+
+connect con1,localhost,root;
+create table t1 (a int, b int);
+create table t2 (c int, d int);
+create view v1 as select c+1 as e, d+1 as f from t2;
+
+SET DEBUG_SYNC= 'table_field_cached SIGNAL in_sync WAIT_FOR go';
+prepare stmt1 from "select a from t1";
+--send execute stmt1
+
+connection default;
+SET DEBUG_SYNC= 'now WAIT_FOR in_sync';
+SET DEBUG_SYNC= 'now SIGNAL go';
+
+connection con1;
+--reap
+
+SET DEBUG_SYNC= 'table_field_cached SIGNAL in_sync WAIT_FOR go';
+prepare stmt1 from "select e from v1";
+--send execute stmt1
+
+connection default;
+SET DEBUG_SYNC= 'now WAIT_FOR in_sync';
+SET DEBUG_SYNC= 'now SIGNAL go';
+
+connection con1;
+--reap
+
+connection default;
+disconnect con1;
+
+SET DEBUG_SYNC = 'RESET';
+drop view v1;
+drop table t1,t2;

sql/sql_base.cc

@@ -5865,7 +5865,10 @@ find_field_in_table(THD *thd, TABLE *table, const char *name, size_t length,
   if (cached_field_index < table->s->fields &&
       !my_strcasecmp(system_charset_info,
                      table->field[cached_field_index]->field_name.str, name))
+  {
     field= table->field[cached_field_index];
+    DEBUG_SYNC(thd, "table_field_cached");
+  }
   else
   {
     LEX_CSTRING fname= {name, length};