MPS: nativecomp ABI

[Pip Cet <pipcet@protonmail.com>]

Hello,

I'm working on scratch/igc. One thing I'd like to do is put the IGC header which all objects will require (for now) into these structs:

struct Lisp_Cons
struct Lisp_Symbol
struct Lisp_String
struct Lisp_Float
union vectorlike_header

IIUC, this means changing the nativecomp ABI hash (which means I'll have to rebuild the .eln files, I think) and adjusting any nativecomp code which knows about the structure layouts. However, I've only been able to find that for Lisp_Cons and struct Lisp_Symbol_With_Pos, which declares its header as ptrdiff_t. Are there more, or do the others all use C functions for access?

Things appear to work, but I'd rather not miss anything and haven't looked at this code in years.

Thanks!
Pip