Re: Flexible array member

[David Malcolm <dmalcolm@redhat.com>]

On Fri, 2021-12-10 at 18:44 +0100, Marc Nieper-Wißkirchen via Jit
wrote:
> C99 (and thus GCC) allow defining structures that end in a flexible
> array
> member ([1]).
> 
> How can this be encoded in libgccjit? Is it valid to create an array
> type
> of length 0 and use that to define the last field in a struct?

I don't know.

I did some quick grepping of the C front-end, and gcc/c/c-decl.c's
grokdeclarator has:

		/* ISO C99 Flexible array members are effectively
		   identical to GCC's zero-length array extension.  */
		if (flexible_array_member || array_parm_vla_unspec_p)
		  itype = build_range_type (sizetype, size_zero_node,
					    NULL_TREE);

So using length 0 for the array type might work in libgccjit, or it
might not, as there might be something else in the IR that libgccjit
needs to set up for it to work properly.  You could try it, I guess.

Sorry not to have a clearer answer.
Dave



> 
> Thanks,
> 
> Marc
> 
> --
> 
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
>