Update src/eval.rs

Co-authored-by: Ralf Jung <post@ralfj.de>

Author: carbotaniuman

src/eval.rs

@@ -77,7 +77,8 @@ pub enum ProvenanceMode {
     /// Int2ptr casts return pointers with an invalid provenance,
     /// i.e., not valid for any memory access.
     Strict,
-    /// Int2ptr casts return pointers valid for any allocation
+    /// Int2ptr casts determine the allocation they point to at cast time.
+    /// All allocations are considered exposed.
     Legacy,
 }