MDEV-16039 Crash when selecting virtual columns generated using functions with DAYNAME()bb-10.5-nikita-expr-arena

Due to collation specifics an Item tree could change while fixing. Virtual fields.

1. This should be done on the correct query arena, which is table->expr_arena.
2. Doing it once per table open is enough. Furthermore, fixing virtual exprs after open sets the collation to the one definde by `SET NAMES`, which is incorrect: only the native table collation should be used, and it shouldn't be changed after the table is created.

1 files changed, 1 insertions, 42 deletions

diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 7ac0dcad596..ff9575bb478 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -5388,45 +5388,6 @@ static void mark_real_tables_as_free_for_reuse(TABLE_LIST *table_list)
 }
 
 
-static bool fix_all_session_vcol_exprs(THD *thd, TABLE_LIST *tables)
-{
-  Security_context *save_security_ctx= thd->security_ctx;
-  TABLE_LIST *first_not_own= thd->lex->first_not_own_table();
-  DBUG_ENTER("fix_session_vcol_expr");
-
-  for (TABLE_LIST *table= tables; table && table != first_not_own;
-       table= table->next_global)
-  {
-    TABLE *t= table->table;
-    if (!table->placeholder() && t->s->vcols_need_refixing &&
-         table->lock_type >= TL_WRITE_ALLOW_WRITE)
-    {
-      if (table->security_ctx)
-        thd->security_ctx= table->security_ctx;
-
-      for (Field **vf= t->vfield; vf && *vf; vf++)
-        if (fix_session_vcol_expr(thd, (*vf)->vcol_info))
-          goto err;
-
-      for (Field **df= t->default_field; df && *df; df++)
-        if ((*df)->default_value &&
-            fix_session_vcol_expr(thd, (*df)->default_value))
-          goto err;
-
-      for (Virtual_column_info **cc= t->check_constraints; cc && *cc; cc++)
-        if (fix_session_vcol_expr(thd, (*cc)))
-          goto err;
-
-      thd->security_ctx= save_security_ctx;
-    }
-  }
-  DBUG_RETURN(0);
-err:
-  thd->security_ctx= save_security_ctx;
-  DBUG_RETURN(1);
-}
-
-
 /**
   Lock all tables in a list.
 
@@ -5587,9 +5548,7 @@ bool lock_tables(THD *thd, TABLE_LIST *tables, uint count, uint flags)
     }
   }
 
-  bool res= fix_all_session_vcol_exprs(thd, tables);
-  if (!res)
-    res= thd->decide_logging_format(tables);
+    bool res= thd->decide_logging_format(tables);
 
   DBUG_RETURN(res);
 }