BUG#5390 - problems with merge tables

After-fix optimizations proposed and finally
implemented by Monty.

mysql-test/r/lock.result

@@ -47,3 +47,14 @@ unlock tables;
 lock tables t1 write, t1 as t1_alias read;
 insert into t1 select index1,nr from t1 as t1_alias;
 drop table t1,t2;
+create table t1 (c1 int);
+create table t2 (c1 int);
+create table t3 (c1 int);
+lock tables t1 write, t2 write, t3 write;
+drop table t2, t3, t1;
+create table t1 (c1 int);
+create table t2 (c1 int);
+create table t3 (c1 int);
+lock tables t1 write, t2 write, t3 write, t1 as t4 read;
+alter table t2 add column c2 int;
+drop table t1, t2, t3;

mysql-test/t/lock.test

@@ -57,3 +57,23 @@ unlock tables;
 lock tables t1 write, t1 as t1_alias read;
 insert into t1 select index1,nr from t1 as t1_alias;
 drop table t1,t2;
+
+#
+# BUG#5390 - problems with merge tables
+# Supplement test for the after-fix optimization
+# Check that a dropped table is correctly removed from a lock.
+create table t1 (c1 int);
+create table t2 (c1 int);
+create table t3 (c1 int);
+lock tables t1 write, t2 write, t3 write;
+# This removes one table after the other from the lock.
+drop table t2, t3, t1;
+#
+# Check that a lock merge works.
+create table t1 (c1 int);
+create table t2 (c1 int);
+create table t3 (c1 int);
+lock tables t1 write, t2 write, t3 write, t1 as t4 read;
+alter table t2 add column c2 int;
+drop table t1, t2, t3;
+

sql/table.h

@@ -86,6 +86,9 @@ struct st_table {
   uint next_number_index;
   uint blob_ptr_size;			/* 4 or 8 */
   uint next_number_key_offset;
+  uint lock_position;                   /* Position in MYSQL_LOCK.table */
+  uint lock_data_start;                 /* Start pos. in MYSQL_LOCK.locks */
+  uint lock_count;                      /* Number of locks */
   int current_lock;			/* Type of lock on table */
   enum tmp_table_type tmp_table;
   my_bool copy_blobs;			/* copy_blobs when storing */