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src/helpers.rs

@@ -401,6 +401,7 @@ fn last_error_place(&mut self) -> InterpResult<'tcx, MPlaceTy<'tcx, Tag>> {
         if let Some(errno_place) = this.active_thread_ref().last_error {
             Ok(errno_place)
         } else {
+            // Allocate new place, set initial value to 0.
             let errno_layout = this.machine.layouts.u32;
             let errno_place = this.allocate(errno_layout, MiriMemoryKind::Machine.into());
             this.write_scalar(Scalar::from_u32(0), errno_place.into())?;