Miri: fix ICE when unwinding past topmost stack frame

diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 630b2890835da86feab408c66fd5f9dc2ea3d339..65736710fce1bb1d26ea14275a46ba170ec5c4ea 100644 (file)
--- a/src/librustc_mir/interpret/eval_context.rs
+++ b/src/librustc_mir/interpret/eval_context.rs
@@ -718,6 +718,10 @@ pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx>
             }
         );
 
+        if unwinding && self.frame_idx() == 0 {
+            throw_ub_format!("unwinding past the topmost frame of the stack");
+        }
+
         ::log_settings::settings().indentation -= 1;
         let frame =
             self.stack_mut().pop().expect("tried to pop a stack frame, but there were none");