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.

2 files changed, 2 insertions, 5 deletions

diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 778d58eeadc..849ffa881df 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -449,11 +449,7 @@ pub trait Emitter {
         span: &mut MultiSpan,
         children: &mut Vec<SubDiagnostic>,
     ) {
-        let source_map = if let Some(ref sm) = source_map {
-            sm
-        } else {
-            return;
-        };
+        let Some(source_map) = source_map else { return };
         debug!("fix_multispans_in_extern_macros: before: span={:?} children={:?}", span, children);
         self.fix_multispan_in_extern_macros(source_map, span);
         for child in children.iter_mut() {
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 60a48b5a2d9..1ccfa06ff67 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -8,6 +8,7 @@
 #![feature(if_let_guard)]
 #![feature(format_args_capture)]
 #![feature(iter_zip)]
+#![feature(let_else)]
 #![feature(nll)]
 
 #[macro_use]