Bug #27493633: REGRESSION IN FEDERATED STORAGE ENGINE AFTER GCC 7 FIXES

Fix a regression after Bug#25943754: FIX GCC 7 COMPILE WARNINGS.
The federated storage engine had a few fall-throughs that were
intentional, but that we assumed were not.

The test case is a contribution from Percona.

Change-Id: Iefffdd7d8d0f578d00a626da01a487543f2034a6
(cherry picked from commit 96faee6db07d4421697cd04f5934a88a574a2f85)

mysql-test/suite/federated/r/percona_bug1739734.result

@@ -0,0 +1,44 @@
+#
+# Bug lp1739734  "Federated table returns error 1430 from storage engine"
+#
+# This is a bug introduced in the artful/gcc7 compilation fixes, caused by
+# a moved break statement.
+CREATE DATABASE federated;
+CREATE DATABASE federated;
+CREATE DATABASE lp1739734;
+use lp1739734;
+CREATE SERVER local_server
+FOREIGN DATA WRAPPER mysql
+OPTIONS (
+HOST '127.0.0.1',
+PORT MASTER_PORT,
+USER 'root',
+PASSWORD '',
+DATABASE 'lp1739734'
+);
+CREATE TABLE remote_table (
+a INT,
+b INT,
+KEY ab (a,b),
+KEY ba (b,a)
+);
+CREATE TABLE local_table (
+a INT,
+b INT,
+KEY ab (a,b),
+KEY ba (b,a)
+) ENGINE=federated CONNECTION='local_server/remote_table';
+SELECT * FROM local_table;
+a	b
+SELECT * FROM local_table USE INDEX (ab)
+WHERE a<1 AND b=0;
+a	b
+SELECT * FROM local_table USE INDEX (ba)
+WHERE a<1 AND b=0;
+a	b
+DROP DATABASE lp1739734;
+DROP SERVER local_server;
+DROP TABLE IF EXISTS federated.t1;
+DROP DATABASE federated;
+DROP TABLE IF EXISTS federated.t1;
+DROP DATABASE federated;

mysql-test/suite/federated/t/percona_bug1739734.test

@@ -0,0 +1,50 @@
+--echo #
+--echo # Bug lp1739734  "Federated table returns error 1430 from storage engine"
+--echo #
+--echo # This is a bug introduced in the artful/gcc7 compilation fixes, caused by
+--echo # a moved break statement.
+
+--source suite/federated/include/federated.inc
+
+connection master;
+CREATE DATABASE lp1739734;
+use lp1739734;
+
+--replace_result $MASTER_MYPORT MASTER_PORT
+eval CREATE SERVER local_server
+FOREIGN DATA WRAPPER mysql
+OPTIONS (
+  HOST '127.0.0.1',
+  PORT $MASTER_MYPORT,
+  USER 'root',
+  PASSWORD '',
+  DATABASE 'lp1739734'
+);
+
+CREATE TABLE remote_table (
+  a INT,
+  b INT,
+  KEY ab (a,b),
+  KEY ba (b,a)
+);
+
+
+CREATE TABLE local_table (
+  a INT,
+  b INT,
+  KEY ab (a,b),
+  KEY ba (b,a)
+) ENGINE=federated CONNECTION='local_server/remote_table';
+
+SELECT * FROM local_table;
+
+SELECT * FROM local_table USE INDEX (ab)
+WHERE a<1 AND b=0;
+
+SELECT * FROM local_table USE INDEX (ba)
+WHERE a<1 AND b=0;
+
+DROP DATABASE lp1739734;
+DROP SERVER local_server;
+
+--source suite/federated/include/federated_cleanup.inc

storage/federated/ha_federated.cc

@@ -1425,8 +1425,9 @@ bool ha_federated::create_where_from_key(String *to,
           {
             goto err;
           }
+          break;
         }
-        break;
+        // Fall through
       case HA_READ_KEY_OR_NEXT:
         DBUG_PRINT("info", ("federated HA_READ_KEY_OR_NEXT %d", i));
         if (emit_key_part_name(&tmp, key_part) ||
@@ -1444,8 +1445,9 @@ bool ha_federated::create_where_from_key(String *to,
               emit_key_part_element(&tmp, key_part, needs_quotes, 0, ptr,
                                     part_length))
             goto err;
+          break;
         }
-        break;
+        // Fall through
       case HA_READ_KEY_OR_PREV:
         DBUG_PRINT("info", ("federated HA_READ_KEY_OR_PREV %d", i));
         if (emit_key_part_name(&tmp, key_part) ||