Rollup merge of #94146 - est31:let_else, r=cjgillot

Adopt let else in more places

Continuation of #89933, #91018, #91481, #93046, #93590, #94011.

I have extended my clippy lint to also recognize tuple passing and match statements. The diff caused by fixing it is way above 1 thousand lines. Thus, I split it up into multiple pull requests to make reviewing easier. This is the biggest of these PRs and handles the changes outside of rustdoc, rustc_typeck, rustc_const_eval, rustc_trait_selection, which were handled in PRs #94139, #94142, #94143, #94144.

2 files changed, 7 insertions, 12 deletions

diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 383250cd68f..82a95faa347 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -1,5 +1,6 @@
 #![feature(crate_visibility_modifier)]
 #![feature(derive_default_enum)]
+#![feature(let_else)]
 #![feature(min_specialization)]
 #![feature(once_cell)]
 #![recursion_limit = "256"]
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 0a4bd23937d..9a92258f809 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -763,12 +763,9 @@ mod parse {
             }
         }
 
-        let v = match v {
-            None => {
-                *slot = Some(MirSpanview::Statement);
-                return true;
-            }
-            Some(v) => v,
+        let Some(v) = v else {
+            *slot = Some(MirSpanview::Statement);
+            return true;
         };
 
         *slot = Some(match v.trim_end_matches('s') {
@@ -792,12 +789,9 @@ mod parse {
             }
         }
 
-        let v = match v {
-            None => {
-                *slot = Some(InstrumentCoverage::All);
-                return true;
-            }
-            Some(v) => v,
+        let Some(v) = v else {
+            *slot = Some(InstrumentCoverage::All);
+            return true;
         };
 
         *slot = Some(match v {