MDEV-4823: Server crashes in Item_func_not::fix_fields on creating a table...

MDEV-4823: Server crashes in Item_func_not::fix_fields on creating a table with a virtual column using NOT

fix_field() call protocol was brocken (zero pointer passed as link to item which is possible only if you are sure that there can not be Items which transforms).

mysql-test/suite/vcol/r/vcol_misc.result

@@ -193,3 +193,10 @@ SELECT COUNT(*) FROM t1;
 COUNT(*)
 2
 DROP TABLE t1;
+#
+# MDEV-4823 Server crashes in Item_func_not::fix_fields on
+# creating a table with a virtual column using NOT
+#
+CREATE TABLE t1 ( f1 INT, v4 INT AS ( NOT f1 ) VIRTUAL );
+drop table t1;
+# end of 5.2 tests

mysql-test/suite/vcol/t/vcol_misc.test

@@ -198,3 +198,11 @@ SELECT COUNT(*) FROM t1;
 
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-4823 Server crashes in Item_func_not::fix_fields on
+--echo # creating a table with a virtual column using NOT
+--echo #
+CREATE TABLE t1 ( f1 INT, v4 INT AS ( NOT f1 ) VIRTUAL );
+drop table t1;
+
+--echo # end of 5.2 tests

sql/table.cc

@@ -1812,7 +1812,7 @@ bool fix_vcol_expr(THD *thd,
   bool result= TRUE;
   TABLE_LIST tables;
   TABLE_LIST *save_table_list, *save_first_table, *save_last_table;
-  int error;
+  int error= 0;
   Name_resolution_context *context;
   const char *save_where;
   char* db_name;
@@ -1860,7 +1860,13 @@ bool fix_vcol_expr(THD *thd,
   save_use_only_table_context= thd->lex->use_only_table_context;
   thd->lex->use_only_table_context= TRUE;
   /* Fix fields referenced to by the virtual column function */
-  error= func_expr->fix_fields(thd, (Item**)0);
+  if (!func_expr->fixed)
+    error= func_expr->fix_fields(thd, &vcol_info->expr_item);
+
+  /* fix_fields could change the expression */
+  func_expr= vcol_info->expr_item;
+  /* Number of columns will be checked later */
+
   /* Restore the original context*/
   thd->lex->use_only_table_context= save_use_only_table_context;
   context->table_list= save_table_list;