Description:
Right now, using mysqlcheck -ACs produces errors whenever in-memory tables(type HEAP) are used. It might be useful that if tables that cannot be corrupted(even a check fails), and the -C flag is used, for tables that haven't been changed since the last check to be skipped, for N/A tables(tables for whom checking would make no sense) to be skipped also.
How to repeat:
mysqlcheck -ACc on a server with at least one database that contains a HEAP table.
Suggested fix:
When both -A and -C options are selected, do not report an error, since what's happening is that the command is meant to check "everything that can be checked" and you can't exclude from check based on table type. Returning an error because HEAP tables can't be checked is just noise pollution, since:
1) they are unlikely to be corrupted
2) even if they are, they can't be checked for the exact error, or fixed, so saying "I can't do that" is just noise.