whitelist platforms where panicking should work

Author: RalfJung

src/shims/foreign_items.rs

@@ -132,6 +132,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 // This matches calls to the foreign item `panic_impl`.
                 // The implementation is provided by the function with the `#[panic_handler]` attribute.
                 "panic_impl" => {
+                    // Make sure panicking actually works on this platform.
+                    match this.tcx.sess.target.target.target_os.as_str() {
+                        "linux" | "macos" => {},
+                        _ => throw_unsup_format!("panicking is not supported on this platform"),
+                    }
+
                     let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
                     let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
                     return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));