Re: [patch] changing lua_Number to int64_t

[Alan Barrett <apb%cequrux.com@localhost>]

On Sun, 17 Nov 2013, Mouse wrote:
> sizeof returns the number of bytes used to store an object. 
> This is only loosely related to the number of data bits in the 
> object; the latter is no more than sizeof the object times 
> CHAR_BIT, but it may be lower.
>
> Also, using an exact-width type assumes that the 
> hardware/compiler in question _has_ such a type.

Yes, that's true of C.

> It's possible that lua, NetBSD, or the combination of the two is 
> willing to write off portability to machines where one or both 
> of those potential portability issues becomes actual.  But that 
> seems to be asking for trouble to me; history is full of "but 
> nobody will ever want to port this to one of _those_" that come 
> back to bite people.

NetBSD already assumes that char is exactly 8 bits, and that 
integer types with exactly 16, 32, and 64 bits exist.  Adding more 
instances of the same assumptions doesn't seem like a big problem 
to me.  If there's ever a need to port to a machine where those 
assumptions do not hold, then we can worry about it at that time, 
but I susect that it will be possible to change to using things 
like int_least64_t (for a type with no less than 64 bits) instead 
of int64_t (for a type with exactly 64 bits).

--apb (Alan Barrett)