MDEV-9443: Add REVOKE <role> as a command to PREPARE

mysql-test/suite/roles/prepare_stmt_with_role.result

@@ -38,6 +38,15 @@ Grants for test_user@%
 GRANT developers TO 'test_user'@'%'
 GRANT USAGE ON *.* TO 'test_user'@'%'
 #
+# Test revoking a role.
+#
+SET @revokeRole = 'REVOKE developers FROM test_user';
+PREPARE stmtRevokeRole FROM @revokeRole;
+EXECUTE stmtRevokeRole;
+SHOW GRANTS FOR test_user;
+Grants for test_user@%
+GRANT USAGE ON *.* TO 'test_user'@'%'
+#
 # Now drop the role.
 #
 SET @dropRole = 'DROP ROLE developers';

mysql-test/suite/roles/prepare_stmt_with_role.test

@@ -32,6 +32,15 @@ EXECUTE stmtGrantRole;
 SELECT * FROM mysql.roles_mapping;
 SHOW GRANTS FOR test_user;
 
+--echo #
+--echo # Test revoking a role.
+--echo #
+SET @revokeRole = 'REVOKE developers FROM test_user';
+PREPARE stmtRevokeRole FROM @revokeRole;
+EXECUTE stmtRevokeRole;
+
+SHOW GRANTS FOR test_user;
+
 --echo #
 --echo # Now drop the role.
 --echo #

sql/sql_prepare.cc

@@ -2465,6 +2465,7 @@ static bool check_prepared_statement(Prepared_statement *stmt)
   case SQLCOM_GRANT:
   case SQLCOM_GRANT_ROLE:
   case SQLCOM_REVOKE:
+  case SQLCOM_REVOKE_ROLE:
   case SQLCOM_KILL:
   case SQLCOM_COMPOUND:
   case SQLCOM_SHUTDOWN: