MDEV-30526 Assertion `rights == merged->cols' failed in update_role_columns

another case of the antipattern "iterate the HASH and delete
elements as we go"

mysql-test/suite/roles/role_grant_propagate.result

@@ -163,5 +163,18 @@ drop role student;
 drop role admin;
 drop database crm;
 #
+# MDEV-30526 Assertion `rights == merged->cols' failed in update_role_columns
+#
+create table t1 ( pk int, i int);
+create role a;
+grant select (i), update (pk) on t1 to a;
+revoke  update (pk) on t1 from a;
+show grants for a;
+Grants for a
+GRANT USAGE ON *.* TO `a`
+GRANT SELECT (`i`) ON `test`.`t1` TO `a`
+drop role a;
+drop table t1;
+#
 # End of 10.3 tests
 #

mysql-test/suite/roles/role_grant_propagate.test

@@ -196,6 +196,17 @@ drop role student;
 drop role admin;
 drop database crm;
 
+--echo #
+--echo # MDEV-30526 Assertion `rights == merged->cols' failed in update_role_columns
+--echo #
+create table t1 ( pk int, i int);
+create role a;
+grant select (i), update (pk) on t1 to a;
+revoke  update (pk) on t1 from a;
+show grants for a;
+drop role a;
+drop table t1;
+
 --echo #
 --echo # End of 10.3 tests
 --echo #

sql/sql_acl.cc

@@ -6550,6 +6550,7 @@ static int update_role_columns(GRANT_TABLE *merged,
     }
   }
 
+restart:
   for (uint i=0 ; i < mh->records ; i++)
   {
     GRANT_COLUMN *col = (GRANT_COLUMN *)my_hash_element(mh, i);
@@ -6558,6 +6559,7 @@ static int update_role_columns(GRANT_TABLE *merged,
     {
       changed= 1;
       my_hash_delete(mh, (uchar*)col);
+      goto restart;
     }
   }
   DBUG_ASSERT(rights == merged->cols);