Re: [PATCH] Objective-C: fix protocol list count type (pertinent to non-LP64)

[Matt Jacobson <mhjacobson@me.com>]

> On Sep 26, 2021, at 11:45 PM, Matt Jacobson <mhjacobson@me.com> wrote:
> 
> Fix protocol list layout for non-LP64.  clang and objc4 both give the `count` 
> field as `long`, not `intptr_t`.  Those are the same on LP64, but not 
> everywhere.  For non-LP64, this fixes binary compatibility with clang-built 
> classes.
> 
> This was more complicated than I anticipated, because the relevant frontend 
> code in fact had no AST type for `protocol_list_t`, instead emitting protocol 
> lists as `protocol_t[]`, with the zeroth element actually being the integer 
> count.  That made it nontrivial to change the count to `long`.  With this 
> change, there is now a true `protocol_list_t` type in the AST.
> 
> Tested multiple ways.  On x86_64/Darwin, I confirmed with a test program that 
> protocol conformances by classes, categories, and protocols works.  On AVR, I 
> manually inspected the generated assembly to confirm that protocol lists gain 
> an extra two bytes of `count`, matching clang.
> 
> Thank you for your time.
> 
> <https://github.com/mhjacobson/gcc/commit/5ebc95dc726f0745ebdf003093f1b8d7720ce32f>

Friendly ping.  Please let me know if there’s anything I can clarify.

Original mail:
<https://gcc.gnu.org/pipermail/gcc-patches/2021-September/580280.html>

Thanks.