interpret/miri: call panic_cannot_unwind lang item instead of hard-coding the same message

3 files changed, 14 insertions, 3 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 3ac6f07e8b7..61d3de5c405 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -765,7 +765,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
             mir::UnwindAction::Terminate => {
                 self.frame_mut().loc = Right(self.frame_mut().body.span);
-                M::abort(self, "panic in a function that cannot unwind".to_owned())?;
+                M::unwind_terminate(self)?;
+                // This might have pushed a new stack frame, or it terminated execution.
+                // Either way, `loc` will not be updated.
+                return Ok(());
             }
         };
         Ok(())
@@ -865,6 +868,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     panic!("encountered StackPopCleanup::Root when unwinding!")
                 }
             };
+            // This must be the very last thing that happens, since it can in fact push a new stack frame.
             self.unwind_to_block(unwind)
         } else {
             // Follow the normal return edge.
diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs
index e101785b6e2..15f2dd17bf5 100644
--- a/compiler/rustc_const_eval/src/interpret/machine.rs
+++ b/compiler/rustc_const_eval/src/interpret/machine.rs
@@ -223,6 +223,9 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
         throw_unsup_format!("aborting execution is not supported")
     }
 
+    /// Called when unwinding reached a state where execution should be terminated.
+    fn unwind_terminate(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx>;
+
     /// Called for all binary operations where the LHS has pointer type.
     ///
     /// Returns a (value, overflowed) pair if the operation succeeded
@@ -500,6 +503,11 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
     }
 
     #[inline(always)]
+    fn unwind_terminate(_ecx: &mut InterpCx<$mir, $tcx, Self>) -> InterpResult<$tcx> {
+        unreachable!("unwinding cannot happen during compile-time evaluation")
+    }
+
+    #[inline(always)]
     fn call_extra_fn(
         _ecx: &mut InterpCx<$mir, $tcx, Self>,
         fn_val: !,
diff --git a/compiler/rustc_const_eval/src/interpret/terminator.rs b/compiler/rustc_const_eval/src/interpret/terminator.rs
index afca6a80319..b2ebcceceb3 100644
--- a/compiler/rustc_const_eval/src/interpret/terminator.rs
+++ b/compiler/rustc_const_eval/src/interpret/terminator.rs
@@ -197,8 +197,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
 
             UnwindTerminate => {
-                // FIXME: maybe should call `panic_no_unwind` lang item instead.
-                M::abort(self, "panic in a function that cannot unwind".to_owned())?;
+                M::unwind_terminate(self)?;
             }
 
             // When we encounter Resume, we've finished unwinding