From 73ba4e7abe0ada4c187aee4576bffe6024b5098a Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 31 Jul 2020 20:46:05 +0200
Subject: [PATCH] Miri: fix ICE when unwinding past topmost stack frame

---
 src/librustc_mir/interpret/eval_context.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 630b2890835..65736710fce 100644
--- 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");
-- 
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