Hi! As this is a SIGSEGV inside rustc, it looks more like a bug in rustc than in hx.
I looked around if there is a similar bug reported against rustc, and https://github.com/rust-lang/rust/issues/147026 has some similarity. Especially the stack trace in the comment at https://github.com/rust-lang/rust/issues/147026#issuecomment-3345971356, which also mentions /lib/x86_64-linux-gnu/libc.so.6(+0x3fdf0) close to the top of the stack. Jan
