thread '<unnamed>' panicked at 'explicit panic', $DIR/unwind_top_of_stack.rs:LL:CC
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: Undefined Behavior: unwinding past the topmost frame of the stack
  --> $DIR/unwind_top_of_stack.rs:LL:CC
   |
LL | / extern "C-unwind" fn thread_start(_null: *mut libc::c_void) -> *mut libc::c_void {
LL | |
LL | |     panic!()
LL | | }
   | |_^ unwinding past the topmost frame of the stack
   |
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE:
   = note: inside `thread_start` at $DIR/unwind_top_of_stack.rs:LL:CC

error: aborting due to previous error