More let_else adoptions

compiler/rustc_save_analysis/src/dump_visitor.rs

@@ -47,11 +47,10 @@ use rls_data::{
 
 use tracing::{debug, error};
 
+#[rustfmt::skip] // https://github.com/rust-lang/rustfmt/issues/5213
 macro_rules! down_cast_data {
     ($id:ident, $kind:ident, $sp:expr) => {
-        let $id = if let super::Data::$kind(data) = $id {
-            data
-        } else {
+        let super::Data::$kind($id) = $id else {
             span_bug!($sp, "unexpected data kind: {:?}", $id);
         };
     };

compiler/rustc_save_analysis/src/lib.rs

@@ -1,6 +1,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(if_let_guard)]
 #![feature(nll)]
+#![feature(let_else)]
 #![recursion_limit = "256"]
 #![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))]