Prefer not accessing the private field of newtype_index types

compiler/rustc_span/src/def_id.rs

@@ -34,7 +34,7 @@ impl CrateNum {
 
 impl fmt::Display for CrateNum {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&self.private, f)
+        fmt::Display::fmt(&self.as_u32(), f)
     }
 }
 

compiler/rustc_span/src/hygiene.rs

@@ -76,7 +76,7 @@ pub struct ExpnId {
 impl fmt::Debug for ExpnId {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // Generate crate_::{{expn_}}.
-        write!(f, "{:?}::{{{{expn{}}}}}", self.krate, self.local_id.private)
+        write!(f, "{:?}::{{{{expn{}}}}}", self.krate, self.local_id.as_u32())
     }
 }