Minor issue - zero-length fixed size arrays in variable-sized structs..

[Joakim via Digitalmars-d]

On Wednesday, 8 July 2009 at 22:55:47 UTC, Jarrett Billingsley 
wrote:
> I noticed in the spec on arrays that "A [fixed-size] array with 
> a
> dimension of 0 is allowed, but no space is allocated for it. 
> It's
> useful as the last member of a variable length struct.."  This 
> sounds
> like C99's "flexible array members," where a struct can have an 
> array
> as its last element that isn't given a size, specifically for 
> allowing
> variable-sized structs.
>
> Well, the issue with a zero-length fixed-size array is that.. 
> uh, you
> can't access anything out of it.  The compiler disallows any 
> indexing
> of a zero-length array with constant indices, and at runtime, 
> all
> accesses caught by the array bounds checking.  Weirder still, 
> the .ptr
> of any zero-length array is always null, so you can't even do 
> things
> like "arr.ptr[5] = x;" (which would be perfectly acceptable in 
> my
> opinion).
>
> Just a silly issue.

Just thought I'd mention that this works now, since this is the 
only forum thread that mentions working with C's flexible array 
members.  You simply define a zero-length array and then access 
it using .ptr, as in this C binding and example program I 
recently translated:

https://github.com/joakim-noah/usrsctp/blob/master/usrsctp.d#L185
https://github.com/joakim-noah/usrsctp/blob/master/programs/rtcweb.d#L836