MDEV-31618: Server crashes in...

MDEV-31618: Server crashes in process_i_s_table_temporary_tables/get_all_tables after alter in rename query

Any TMP_TABLE_SHARE must always have at least one TABLE instance.
So whenever a temporary TABLE that is marked for reopen is closed,
reopen it at once if its TMP_TABLE_SHARE list of tables becomes empty.

mysql-test/main/information_schema_temp_table.result

@@ -266,3 +266,56 @@ mysqltest	s1
 DROP TABLE seq1;
 DROP TABLE mysqltest.s1;
 DROP TABLE mysqltest.s2;
+#
+# MDEV-31618: Server crashes in
+#             process_i_s_table_temporary_tables/get_all_tables after alter in rename
+#
+CREATE  table seq1 (a bigint, b int);
+CREATE  TEMPORARY TABLE tmp LIKE seq1;
+INSERT  tmp SELECT * FROM seq1;
+ALTER  TABLE tmp RENAME TO seq1;
+ALTER TABLE seq1 CHANGE a b int ;
+Got one of the listed errors
+RENAME  TABLE seq1 TO seq1;
+ERROR 42S01: Table 'seq1' already exists
+show  full tables;
+Tables_in_test	Table_type
+seq1	TEMPORARY TABLE
+seq1	BASE TABLE
+drop table seq1;
+drop table seq1;
+CREATE  SEQUENCE seq2;
+CREATE  TEMPORARY sequence tmp;
+show  full tables;
+Tables_in_test	Table_type
+tmp	TEMPORARY SEQUENCE
+seq2	SEQUENCE
+ALTER  table `tmp` RENAME TO seq1;
+show  full tables;
+Tables_in_test	Table_type
+seq1	TEMPORARY SEQUENCE
+seq2	SEQUENCE
+ALTER TABLE `seq1` CHANGE `cache_size` cache_size int ;
+ERROR HY000: Sequence 'test.seq1' table structure is invalid (cache_size)
+show  full tables;
+Tables_in_test	Table_type
+seq1	TEMPORARY SEQUENCE
+seq2	SEQUENCE
+RENAME  TABLE seq1 TO seq1;
+ERROR 42S01: Table 'seq1' already exists
+show  full tables;
+Tables_in_test	Table_type
+seq1	TEMPORARY SEQUENCE
+seq2	SEQUENCE
+RENAME  TABLE seq1 TO seq3;
+show  full tables;
+Tables_in_test	Table_type
+seq3	TEMPORARY SEQUENCE
+seq2	SEQUENCE
+drop table seq2;
+show  full tables;
+Tables_in_test	Table_type
+seq3	TEMPORARY SEQUENCE
+drop table seq3;
+show  full tables;
+Tables_in_test	Table_type

mysql-test/main/information_schema_temp_table.test

@@ -242,3 +242,39 @@ SELECT table_schema, table_name FROM  INFORMATION_SCHEMA.TABLES WHERE table_type
 DROP TABLE seq1;
 DROP TABLE mysqltest.s1;
 DROP TABLE mysqltest.s2;
+
+--echo #
+--echo # MDEV-31618: Server crashes in
+--echo #             process_i_s_table_temporary_tables/get_all_tables after alter in rename
+--echo #
+# Check on temporary tables
+CREATE  table seq1 (a bigint, b int);
+CREATE  TEMPORARY TABLE tmp LIKE seq1;
+INSERT  tmp SELECT * FROM seq1;
+ALTER  TABLE tmp RENAME TO seq1;
+--error 4086,1060
+ALTER TABLE seq1 CHANGE a b int ;
+--error 1050
+RENAME  TABLE seq1 TO seq1;
+show  full tables;
+drop table seq1;
+drop table seq1;
+
+# Check on sequences
+CREATE  SEQUENCE seq2;
+CREATE  TEMPORARY sequence tmp;
+show  full tables;
+ALTER  table `tmp` RENAME TO seq1;
+show  full tables;
+--error ER_SEQUENCE_INVALID_TABLE_STRUCTURE
+ALTER TABLE `seq1` CHANGE `cache_size` cache_size int ;
+show  full tables;
+--error ER_TABLE_EXISTS_ERROR
+RENAME  TABLE seq1 TO seq1;
+show  full tables;
+RENAME  TABLE seq1 TO seq3;
+show  full tables;
+drop table seq2;
+show  full tables;
+drop table seq3;
+show  full tables;

sql/temporary_tables.cc

@@ -1086,8 +1086,13 @@ TABLE *THD::find_temporary_table(const char *key, uint key_length,
       {
         share->all_tmp_tables.remove(table);
         free_temporary_table(table);
-        it.rewind();
-        continue;
+        if (share->all_tmp_tables.is_empty())
+          table= open_temporary_table(share, share->table_name.str);
+        else
+        {
+          it.rewind();
+          continue;
+        }
       }
       result= table;
       break;