Adopt let else in more places

compiler/rustc_lint/src/context.rs

@@ -278,9 +278,8 @@ impl LintStore {
     /// This lint has been renamed; warn about using the new name and apply the lint.
     #[track_caller]
     pub fn register_renamed(&mut self, old_name: &str, new_name: &str) {
-        let target = match self.by_name.get(new_name) {
-            Some(&Id(lint_id)) => lint_id,
-            _ => bug!("invalid lint renaming of {} to {}", old_name, new_name),
+        let Some(&Id(target)) = self.by_name.get(new_name) else {
+            bug!("invalid lint renaming of {} to {}", old_name, new_name);
         };
         self.by_name.insert(old_name.to_string(), Renamed(new_name.to_string(), target));
     }

compiler/rustc_lint/src/internal.rs

@@ -23,10 +23,7 @@ declare_lint_pass!(DefaultHashTypes => [DEFAULT_HASH_TYPES]);
 
 impl LateLintPass<'_> for DefaultHashTypes {
     fn check_path(&mut self, cx: &LateContext<'_>, path: &Path<'_>, hir_id: HirId) {
-        let def_id = match path.res {
-            Res::Def(rustc_hir::def::DefKind::Struct, id) => id,
-            _ => return,
-        };
+        let Res::Def(rustc_hir::def::DefKind::Struct, def_id) = path.res else { return };
         if matches!(cx.tcx.hir().get(hir_id), Node::Item(Item { kind: ItemKind::Use(..), .. })) {
             // don't lint imports, only actual usages
             return;

compiler/rustc_lint/src/levels.rs

@@ -95,9 +95,9 @@ impl<'s> LintLevelsBuilder<'s> {
             let orig_level = level;
             let lint_flag_val = Symbol::intern(lint_name);
 
-            let ids = match store.find_lints(&lint_name) {
-                Ok(ids) => ids,
-                Err(_) => continue, // errors handled in check_lint_name_cmdline above
+            let Ok(ids) = store.find_lints(&lint_name) else {
+                // errors handled in check_lint_name_cmdline above
+                continue
             };
             for id in ids {
                 // ForceWarn and Forbid cannot be overriden

compiler/rustc_lint/src/non_ascii_idents.rs

@@ -301,10 +301,7 @@ impl EarlyLintPass for NonAsciiIdents {
                     BTreeMap::new();
 
                 'outerloop: for (augment_script_set, usage) in script_states {
-                    let (mut ch_list, sp) = match usage {
-                        ScriptSetUsage::Verified => continue,
-                        ScriptSetUsage::Suspicious(ch_list, sp) => (ch_list, sp),
-                    };
+                    let ScriptSetUsage::Suspicious(mut ch_list, sp) = usage else { continue };
 
                     if augment_script_set.is_all() {
                         continue;

compiler/rustc_lint/src/types.rs

@@ -1331,14 +1331,7 @@ impl<'tcx> LateLintPass<'tcx> for VariantSizeDifferences {
         if let hir::ItemKind::Enum(ref enum_definition, _) = it.kind {
             let t = cx.tcx.type_of(it.def_id);
             let ty = cx.tcx.erase_regions(t);
-            let layout = match cx.layout_of(ty) {
-                Ok(layout) => layout,
-                Err(
-                    ty::layout::LayoutError::Unknown(_)
-                    | ty::layout::LayoutError::SizeOverflow(_)
-                    | ty::layout::LayoutError::NormalizationFailure(_, _),
-                ) => return,
-            };
+            let Ok(layout) = cx.layout_of(ty) else { return };
             let Variants::Multiple {
                     tag_encoding: TagEncoding::Direct, tag, ref variants, ..
                 } = &layout.variants else {