explain a good reason for why LocalValue does not store the type of t…

…he local
rust-lang · Nov 30, 2023 · a1b03e3 · a1b03e3
1 parent df0295f
commit a1b03e3
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -173,6 +173,9 @@ impl<Prov: Provenance> std::fmt::Debug for LocalState<'_, Prov> {
 }
 
 /// Current value of a local variable
+///
+/// This does not store the type of the local; the type is given by `body.local_decls` and can never
+/// change, so by not storing here we avoid having to maintain that as an invariant.
 #[derive(Copy, Clone, Debug)] // Miri debug-prints these
 pub(super) enum LocalValue<Prov: Provenance = AllocId> {
     /// This local is not currently alive, and cannot be used at all.