MDEV-12809 Bad column type created for TEXT(1431655798) CHARACTER SET utf8

mysql-test/r/type_blob.result

@@ -1063,3 +1063,19 @@ DROP TABLE t1;
 #
 # End of 5.5 tests
 #
+#
+# Start of 10.2 test
+#
+#
+# MDEV-12809 Bad column type created for TEXT(1431655798) CHARACTER SET utf8
+#
+CREATE TABLE t1 (a TEXT(1431655798) CHARACTER SET utf8);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` longtext CHARACTER SET utf8 DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;
+#
+# End of 10.2 test
+#

mysql-test/t/type_blob.test

@@ -680,3 +680,21 @@ DROP TABLE t1;
 --echo #
 --echo # End of 5.5 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.2 test
+--echo #
+
+--echo #
+--echo # MDEV-12809 Bad column type created for TEXT(1431655798) CHARACTER SET utf8
+--echo #
+
+CREATE TABLE t1 (a TEXT(1431655798) CHARACTER SET utf8);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+
+--echo #
+--echo # End of 10.2 test
+--echo #

sql/field.cc

@@ -9777,7 +9777,7 @@ void Column_definition::create_length_to_internal_length(void)
   case MYSQL_TYPE_STRING:
   case MYSQL_TYPE_VARCHAR:
     length*= charset->mbmaxlen;
-    DBUG_ASSERT(length <= UINT_MAX32);
+    set_if_smaller(length, UINT_MAX32);
     key_length= (uint32)length;
     pack_length= calc_pack_length(sql_type, key_length);
     break;