7 - Make more use of let_chains

Continuation of #94376.

cc #53667

compiler/rustc_mir_transform/src/lib.rs

@@ -1,16 +1,17 @@
+#![allow(rustc::potential_query_instability)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
 #![feature(crate_visibility_modifier)]
+#![feature(let_chains)]
 #![feature(let_else)]
 #![feature(map_try_insert)]
 #![feature(min_specialization)]
-#![feature(option_get_or_insert_default)]
-#![feature(once_cell)]
 #![feature(never_type)]
+#![feature(once_cell)]
+#![feature(option_get_or_insert_default)]
 #![feature(trusted_step)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
-#![allow(rustc::potential_query_instability)]
 
 #[macro_use]
 extern crate tracing;