Bug#22018999: gcols: assertion failed: !error

This problem occurs because we have inconsistent handling of evaluation
of various errors when evaluating constant expressions in generated
columns: Sometimes such errors are reported as errors, sometimes they
are converted to warnings. In strict mode, there is no problem because
they are consistently reported as errors.

The solution to the problem is to temporarily raise strict mode when
checking generated column expressions when creating or altering tables.

Note that this is a change of behavior that should be mentioned in manual.

Author: roylyseng

mysql-test/suite/gcol/r/gcol_bugfixes.result

@@ -573,3 +573,17 @@ SELECT * FROM t1;
 a	b	c
 1	1	11
 DROP TABLE t1;
+# Bug#22018999: gcols: assertion failed: !error
+SET @save_old_sql_mode= @@sql_mode;
+SET sql_mode="";
+Warnings:
+Warning	3090	Changing sql mode 'NO_AUTO_CREATE_USER' is deprecated. It will be removed in a future release.
+CREATE TABLE t (a INTEGER AS (SUBSTR('','a',1))) engine=innodb;
+ERROR 22007: Truncated incorrect INTEGER value: 'a'
+CREATE TABLE t (a INTEGER) engine=innodb;
+ALTER TABLE t ADD b INTEGER AS (SUBSTR('','a',1));
+ERROR 22007: Truncated incorrect INTEGER value: 'a'
+DROP TABLE t;
+set sql_mode= @save_old_sql_mode;
+Warnings:
+Warning	3090	Changing sql mode 'NO_AUTO_CREATE_USER' is deprecated. It will be removed in a future release.

mysql-test/suite/gcol/t/gcol_bugfixes.test

@@ -545,3 +545,20 @@ SELECT * FROM t1;
 FLUSH TABLES;
 SELECT * FROM t1;
 DROP TABLE t1;
+
+--echo # Bug#22018999: gcols: assertion failed: !error
+
+SET @save_old_sql_mode= @@sql_mode;
+SET sql_mode="";
+
+--error ER_TRUNCATED_WRONG_VALUE
+CREATE TABLE t (a INTEGER AS (SUBSTR('','a',1))) engine=innodb;
+
+CREATE TABLE t (a INTEGER) engine=innodb;
+
+--error ER_TRUNCATED_WRONG_VALUE
+ALTER TABLE t ADD b INTEGER AS (SUBSTR('','a',1));
+
+DROP TABLE t;
+
+set sql_mode= @save_old_sql_mode;

sql/table.cc

@@ -2855,6 +2855,10 @@ static bool unpack_gcol_info_from_frm(THD *thd,
   char *gcol_expr_str;
   int str_len= 0;
   const CHARSET_INFO *old_character_set_client;
+  bool disable_strict_mode= false;
+  bool status;
+
+  Strict_error_handler strict_handler;
 
   if (!(gcol_expr_str= (char*) alloc_root(&table->mem_root,
                                           gcol_expr->length +
@@ -2911,8 +2915,23 @@ static bool unpack_gcol_info_from_frm(THD *thd,
   /* From now on use gcol_info generated by the parser. */
   field->gcol_info= thd->lex->gcol_info;
 
+  /* Use strict mode regardless of strict mode setting when validating */
+  if (!thd->is_strict_mode())
+  {
+    thd->variables.sql_mode|= MODE_STRICT_ALL_TABLES;
+    thd->push_internal_handler(&strict_handler);
+    disable_strict_mode= true;
+  }
+
   /* Validate the Item tree. */
-  if (fix_fields_gcol_func(thd, field))
+  status= fix_fields_gcol_func(thd, field);
+
+  if (disable_strict_mode)
+  {
+    thd->pop_internal_handler();
+    thd->variables.sql_mode&= ~MODE_STRICT_ALL_TABLES;
+  }
+  if (status)
   {
     if (is_create_table)
     {