MDEV-15338 Crash in debug build when dropping column that is part of CHECK

Crash happened when deleting all columns that was part of a check constraint

The bug was that read map for from table was used when
checking CHECK constraint and was not properly reset
in copy_data_between_tables()

mysql-test/r/check.result

@@ -52,3 +52,36 @@ connection default;
 UNLOCK TABLES;
 DROP TABLE t1;
 disconnect con1;
+#
+# MDEV-15338
+# Assertion `!table || (!table->read_set ||
+# bitmap_is_set(table->read_set, field_index))'
+# failed on dropping column with CHECK
+#
+CREATE TABLE t1 (a INT, b INT, CHECK (a>0)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1,2),(3,4);
+ALTER TABLE t1 DROP COLUMN a;
+CREATE OR REPLACE TABLE t1 (a INT, b INT, CHECK (a>0)) ENGINE=MyISAM;
+ALTER TABLE t1 DROP COLUMN b;
+CREATE OR REPLACE TABLE t1 (a INT, b INT, c INT, CHECK (a+b>0)) ENGINE=MyISAM;
+ALTER TABLE t1 DROP COLUMN b;
+ERROR 42S22: Unknown column 'b' in 'CHECK'
+ALTER TABLE t1 DROP COLUMN a, DROP COLUMN b;
+CREATE OR REPLACE TABLE t1 (a INT, b INT, c INT, CHECK (a+b>0)) ENGINE=MyISAM;
+ALTER TABLE t1 DROP CONSTRAINT `CONSTRAINT_1`;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL,
+  `b` int(11) DEFAULT NULL,
+  `c` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+CREATE OR REPLACE TABLE t1 (a INT, b INT, c INT, CHECK (a+b>0)) ENGINE=MyISAM;
+ALTER TABLE t1 DROP COLUMN b, DROP CONSTRAINT `CONSTRAINT_1`;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` int(11) DEFAULT NULL,
+  `c` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;

mysql-test/t/check.test

@@ -79,3 +79,27 @@ disconnect con1;
 
 # Wait till we reached the initial number of concurrent sessions
 --source include/wait_until_count_sessions.inc
+
+--echo #
+--echo # MDEV-15338
+--echo # Assertion `!table || (!table->read_set ||
+--echo # bitmap_is_set(table->read_set, field_index))'
+--echo # failed on dropping column with CHECK
+--echo #
+
+CREATE TABLE t1 (a INT, b INT, CHECK (a>0)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (1,2),(3,4);
+ALTER TABLE t1 DROP COLUMN a;
+CREATE OR REPLACE TABLE t1 (a INT, b INT, CHECK (a>0)) ENGINE=MyISAM;
+ALTER TABLE t1 DROP COLUMN b;
+CREATE OR REPLACE TABLE t1 (a INT, b INT, c INT, CHECK (a+b>0)) ENGINE=MyISAM;
+--error ER_BAD_FIELD_ERROR
+ALTER TABLE t1 DROP COLUMN b;
+ALTER TABLE t1 DROP COLUMN a, DROP COLUMN b;
+CREATE OR REPLACE TABLE t1 (a INT, b INT, c INT, CHECK (a+b>0)) ENGINE=MyISAM;
+ALTER TABLE t1 DROP CONSTRAINT `CONSTRAINT_1`;
+SHOW CREATE TABLE t1;
+CREATE OR REPLACE TABLE t1 (a INT, b INT, c INT, CHECK (a+b>0)) ENGINE=MyISAM;
+ALTER TABLE t1 DROP COLUMN b, DROP CONSTRAINT `CONSTRAINT_1`;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;

sql/sql_table.cc

@@ -9844,6 +9844,11 @@ copy_data_between_tables(THD *thd, TABLE *from, TABLE *to,
 
   alter_table_manage_keys(to, from->file->indexes_are_disabled(), keys_onoff);
 
+  /* Set read map for all fields in from table */
+  from->default_column_bitmaps();
+  bitmap_set_all(from->read_set);
+  from->file->column_bitmaps_signal();
+
   /* We can abort alter table for any table type */
   thd->abort_on_warning= !ignore && thd->is_strict_mode();