Re: master 3ed79cd: Separate bytecode stack

[Stefan Monnier]

Eli Zaretskii [2022-03-15 16:42:01] wrote:

>> From: Mattias Engdegård <mattiase@acm.org>
>> Date: Tue, 15 Mar 2022 15:20:29 +0100
>> Cc: Emacs-Devel <emacs-devel@gnu.org>
>> 
>> >> The latter alternative would become a little more palatable if we could 
>> >> use flexible array struct members on all platforms. Given that we assume 
>> >> C99, can we do that now?
>> > 
>> > What do you mean by "flexible array struct members"?  Please show a
>> > code snippet.
>> 
>> I'm sure you know it well, it's the ability to put an incomplete array
>> declaration as the last member of a struct, as in:
>> 
>>  struct S { int n; float a[]; };
>> 
>> which roughly means the same thing as declaring that array to be of size 
>> zero.
>> It's not required in our case but would make the next_stack function (see 
>> patch) go away.
>
> I think you can use this (we already use it elsewhere in Emacs).

AFAICT we usually use:

    struct Lisp_Vector
      {
        union vectorlike_header header;
        Lisp_Object contents[FLEXIBLE_ARRAY_MEMBER];
      } GCALIGNED_STRUCT;

but I suspect that by now we don't need this compatibility hack.


        Stefan