make_path_absolute() should be defined in master.c for mudlib.n.

COMPAT_MODE should be renamed to COMPAT_FLAG.

A lot of calls to xalloc() should be replaced with alloca().

access_check.c uses time(0), which is unportable. It would be better
to use functions in port.c.

Can 'user' for a player object be 0 ?

switch and break / continue in loops won't give offset overflow errors.
  There should actually be a way to have switch tables > 64 KB.

At compile time, it should be checked that functions and lambda closures don't
need more than EVALUATOR_STACK_SIZE space on the stack.

There is no limit for the memory a user can claim.