MDEV-16110 ALTER with ALGORITHM=INPLACE breaks temporary table with virtual columns

Part two, temporary tables.

Make temporary tables respect TABLE::m_needs_reopen.

See also 77cd754229

mysql-test/r/alter_table_errors.result

@@ -8,3 +8,22 @@ t	CREATE TABLE `t` (
   `v` int(11) GENERATED ALWAYS AS (`a`) VIRTUAL
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1
 drop table t;
+create temporary table t1 (a int, v int as (a));
+alter table t1 change column a b int, algorithm=inplace;
+ERROR 0A000: ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY
+show create table t1;
+Table	Create Table
+t1	CREATE TEMPORARY TABLE `t1` (
+  `a` int(11) DEFAULT NULL,
+  `v` int(11) GENERATED ALWAYS AS (`a`) VIRTUAL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+create temporary table t2 (a int, v int as (a));
+lock table t2 write;
+alter table t2 change column a b int, algorithm=inplace;
+ERROR 0A000: ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY
+show create table t2;
+Table	Create Table
+t2	CREATE TEMPORARY TABLE `t2` (
+  `a` int(11) DEFAULT NULL,
+  `v` int(11) GENERATED ALWAYS AS (`a`) VIRTUAL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1

mysql-test/t/alter_table_errors.test

@@ -8,3 +8,14 @@ create table t (a int, v int as (a)) engine=innodb;
 alter table t change column a b tinyint, algorithm=inplace;
 show create table t;
 drop table t;
+
+create temporary table t1 (a int, v int as (a));
+--error ER_ALTER_OPERATION_NOT_SUPPORTED
+alter table t1 change column a b int, algorithm=inplace;
+show create table t1;
+
+create temporary table t2 (a int, v int as (a));
+lock table t2 write;
+--error ER_ALTER_OPERATION_NOT_SUPPORTED
+alter table t2 change column a b int, algorithm=inplace;
+show create table t2;

sql/temporary_tables.cc

@@ -1042,6 +1042,13 @@ TABLE *THD::find_temporary_table(const char *key, uint key_length,
         case TMP_TABLE_ANY:        found= true;                 break;
         }
       }
+      if (table && unlikely(table->m_needs_reopen))
+      {
+        share->all_tmp_tables.remove(table);
+        free_temporary_table(table);
+        it.rewind();
+        continue;
+      }
       result= table;
       break;
     }