andrewrk: This CI failure looks like the ones that happened in #6415, #6416, although they happened on linux and triggered a compiler assert (analyze.cpp:8376, in resolve_llvm_types_struct)
I started debugging this yesterday but only managed to reproduce it once, on a linux x84_64 host, running the behavior-aarch64-linux-gnu-Debug-c-multi test.
The relevant struct type that was not fully resolved and tripped the assert was std.builtin.StackTrace

Not entirely sure this is the same issue but it looks like it, at least superficially