comment

src/stacked_borrows.rs

@@ -633,6 +633,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         }
 
         // We only reborrow "bare" references/boxes.
+        // Not traversing into fields helps with <https://github.com/rust-lang/unsafe-code-guidelines/issues/125>,
+        // but might also cost us optimization and analyses. We will have to experiment more with this.
         if let Some((mutbl, protector)) = qualify(place.layout.ty, kind) {
             // Fast path.
             let val = this.read_immediate(this.place_to_op(place)?)?;