I think this is related to the issue I ran into on aarch64 Linux, commented in issue #1012.

   type Portable_Path is new String with
      Dynamic_Predicate => (for all Char of Portable_Path => Char /= '\');
   --  A portable path always uses forward slashes. For use in the current
   --  platform, it should be adapted first.

Whenever the dynamic predicate on Portable_Path is executed, alr crashes with SIGABRT on OpenBSD 7.1 with GNAT 11.2.0 from the ports collection (gnat_external from alire's point of view).

With ktrace, I was able to determine the abort reason as "reversed memcpy". My understanding is that this is thrown when the src and dst arguments to memcpy overlap. I have no idea why GNAT would do that.

As in my comment on the other issue, adding Alignment => 2 to the Portable_Path type appears to fix the crash. This feels like a workaround for a compiler bug though, so I'm not sure that patching Alire is the right approach.

I'm reporting this issue here for visibility, but I think it needs more investigation to understand why GNAT is generating code this way.