StorageLive: refresh storage (instead of UB) when local is already live

2 files changed, 3 insertions, 7 deletions

diff --git a/compiler/rustc_const_eval/messages.ftl b/compiler/rustc_const_eval/messages.ftl
index 2dbeb7d5e0c..14c036b8df9 100644
--- a/compiler/rustc_const_eval/messages.ftl
+++ b/compiler/rustc_const_eval/messages.ftl
@@ -73,8 +73,6 @@ const_eval_division_by_zero =
     dividing by zero
 const_eval_division_overflow =
     overflow in signed division (dividing MIN by -1)
-const_eval_double_storage_live =
-    StorageLive on a local that was already live
 
 const_eval_dyn_call_not_a_method =
     `dyn` call trying to call something that is not a method
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index 7c2100fcbe3..c1daa2fac33 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -1103,11 +1103,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             Operand::Immediate(Immediate::Uninit)
         });
 
-        // StorageLive expects the local to be dead, and marks it live.
+        // If the local is already live, deallocate its old memory.
         let old = mem::replace(&mut self.frame_mut().locals[local].value, local_val);
-        if !matches!(old, LocalValue::Dead) {
-            throw_ub_custom!(fluent::const_eval_double_storage_live);
-        }
+        self.deallocate_local(old)?;
         Ok(())
     }
 
@@ -1121,7 +1119,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         assert!(local != mir::RETURN_PLACE, "Cannot make return place dead");
         trace!("{:?} is now dead", local);
 
-        // It is entirely okay for this local to be already dead (at least that's how we currently generate MIR)
+        // If the local is already dead, this is a NOP.
         let old = mem::replace(&mut self.frame_mut().locals[local].value, LocalValue::Dead);
         self.deallocate_local(old)?;
         Ok(())