Merge 10.3 into 10.4

mysql-test/suite/innodb/r/instant_alter_upgrade.result

+#
+# MDEV-26577 InnoDB: Failing assertion: dict_tf2_is_valid(flags, flags2)
+# during ADD COLUMN
+#
+CREATE TABLE t1(a INT PRIMARY KEY) ENGINE=InnoDB ROW_FORMAT=COMPRESSED;
+CREATE TABLE t2(a INT PRIMARY KEY) ENGINE=InnoDB;
+FLUSH TABLES;
+ALTER TABLE t2 ADD COLUMN b INT;
+DROP TABLE t1,t2;

mysql-test/suite/innodb/t/instant_alter_upgrade.test

+--source include/have_innodb.inc
+--source include/innodb_row_format.inc
+
+--echo #
+--echo # MDEV-26577 InnoDB: Failing assertion: dict_tf2_is_valid(flags, flags2)
+--echo # during ADD COLUMN
+--echo #
+
+CREATE TABLE t1(a INT PRIMARY KEY) ENGINE=InnoDB ROW_FORMAT=COMPRESSED;
+CREATE TABLE t2(a INT PRIMARY KEY) ENGINE=InnoDB;
+FLUSH TABLES;
+--let $datadir=`select @@datadir`
+--remove_file $datadir/test/t2.frm
+--copy_file $datadir/test/t1.frm $datadir/test/t2.frm
+ALTER TABLE t2 ADD COLUMN b INT;
+DROP TABLE t1,t2;

storage/innobase/buf/buf0buf.cc

@@ -1242,10 +1242,13 @@ buf_madvise_do_dump()
 }
 #endif
 
+#ifndef UNIV_DEBUG
 static inline byte hex_to_ascii(byte hex_digit)
 {
-  return hex_digit <= 9 ? '0' + hex_digit : ('a' - 10) + hex_digit;
+  const int offset= hex_digit <= 9 ? '0' : 'a' - 10;
+  return byte(hex_digit + offset);
 }
+#endif
 
 /** Dump a page to stderr.
 @param[in]	read_buf	database page

storage/innobase/handler/handler0alter.cc

@@ -6279,8 +6279,10 @@ prepare_inplace_alter_table_dict(
 		/* If we promised ALGORITHM=NOCOPY or ALGORITHM=INSTANT,
 		we must retain the original ROW_FORMAT of the table. */
 		flags = (user_table->flags & (DICT_TF_MASK_COMPACT
+					      | DICT_TF_MASK_ZIP_SSIZE
 					      | DICT_TF_MASK_ATOMIC_BLOBS))
 			| (flags & ~(DICT_TF_MASK_COMPACT
+				     | DICT_TF_MASK_ZIP_SSIZE
 				     | DICT_TF_MASK_ATOMIC_BLOBS));
 	}