Adopt let_else across the compiler

This performs a substitution of code following the pattern:

let <id> = if let <pat> = ... { identity } else { ... : ! };

To simplify it to:

let <pat> = ... { identity } else { ... : ! };

By adopting the let_else feature.

3 files changed, 4 insertions, 7 deletions

diff --git a/compiler/rustc_query_system/src/lib.rs b/compiler/rustc_query_system/src/lib.rs
index bc23de069b0..1b992cdb0c9 100644
--- a/compiler/rustc_query_system/src/lib.rs
+++ b/compiler/rustc_query_system/src/lib.rs
@@ -3,6 +3,7 @@
 #![feature(core_intrinsics)]
 #![feature(hash_raw_entry)]
 #![feature(iter_zip)]
+#![feature(let_else)]
 #![feature(min_specialization)]
 #![feature(thread_local_const_init)]
 
diff --git a/compiler/rustc_query_system/src/query/job.rs b/compiler/rustc_query_system/src/query/job.rs
index 98b2a450b19..bd673030992 100644
--- a/compiler/rustc_query_system/src/query/job.rs
+++ b/compiler/rustc_query_system/src/query/job.rs
@@ -644,9 +644,7 @@ pub fn print_query_stack<CTX: QueryContext>(
         if Some(i) == num_frames {
             break;
         }
-        let query_info = if let Some(info) = query_map.as_ref().and_then(|map| map.get(&query)) {
-            info
-        } else {
+        let Some(query_info) = query_map.as_ref().and_then(|map| map.get(&query)) else {
             break;
         };
         let mut diag = Diagnostic::new(
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index 07d72059975..d3c75635783 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -761,11 +761,9 @@ where
         return false;
     }
 
-    let key = if let Some(key) =
+    let Some(key) =
         <Q::Key as DepNodeParams<CTX::DepContext>>::recover(*tcx.dep_context(), &dep_node)
-    {
-        key
-    } else {
+    else {
         return false;
     };