fix more clippy::style findings

match_result_ok
obfuscated_if_else
single_char_add
writeln_empty_string
collapsible_match
iter_cloned_collect
unnecessary_mut_passed

3 files changed, 13 insertions, 13 deletions

diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index 9d4c2900eaf..4abb1d90f44 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -259,8 +259,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         body.as_deref(),
                     );
 
-                    let mut itctx = ImplTraitContext::Universal;
-                    let (generics, decl) = this.lower_generics(generics, id, &mut itctx, |this| {
+                    let itctx = ImplTraitContext::Universal;
+                    let (generics, decl) = this.lower_generics(generics, id, &itctx, |this| {
                         let ret_id = asyncness.opt_return_id();
                         this.lower_fn_decl(&decl, id, *fn_sig_span, FnDeclKind::Fn, ret_id)
                     });
@@ -369,9 +369,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // method, it will not be considered an in-band
                 // lifetime to be added, but rather a reference to a
                 // parent lifetime.
-                let mut itctx = ImplTraitContext::Universal;
+                let itctx = ImplTraitContext::Universal;
                 let (generics, (trait_ref, lowered_ty)) =
-                    self.lower_generics(ast_generics, id, &mut itctx, |this| {
+                    self.lower_generics(ast_generics, id, &itctx, |this| {
                         let trait_ref = trait_ref.as_ref().map(|trait_ref| {
                             this.lower_trait_ref(
                                 trait_ref,
@@ -590,9 +590,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
             kind: match &i.kind {
                 ForeignItemKind::Fn(box Fn { sig, generics, .. }) => {
                     let fdec = &sig.decl;
-                    let mut itctx = ImplTraitContext::Universal;
+                    let itctx = ImplTraitContext::Universal;
                     let (generics, (fn_dec, fn_args)) =
-                        self.lower_generics(generics, i.id, &mut itctx, |this| {
+                        self.lower_generics(generics, i.id, &itctx, |this| {
                             (
                                 // Disallow `impl Trait` in foreign items.
                                 this.lower_fn_decl(
@@ -1184,8 +1184,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         is_async: Option<(NodeId, Span)>,
     ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
         let header = self.lower_fn_header(sig.header);
-        let mut itctx = ImplTraitContext::Universal;
-        let (generics, decl) = self.lower_generics(generics, id, &mut itctx, |this| {
+        let itctx = ImplTraitContext::Universal;
+        let (generics, decl) = self.lower_generics(generics, id, &itctx, |this| {
             this.lower_fn_decl(&sig.decl, id, sig.span, kind, is_async)
         });
         (generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) })
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index db2527a200c..27e91095b28 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -2031,7 +2031,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         output: &FnRetTy,
         span: Span,
-        mut nested_impl_trait_context: ImplTraitContext,
+        nested_impl_trait_context: ImplTraitContext,
     ) -> hir::GenericBound<'hir> {
         // Compute the `T` in `Future<Output = T>` from the return type.
         let output_ty = match output {
@@ -2039,7 +2039,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 // Not `OpaqueTyOrigin::AsyncFn`: that's only used for the
                 // `impl Future` opaque type that `async fn` implicitly
                 // generates.
-                self.lower_ty(ty, &mut nested_impl_trait_context)
+                self.lower_ty(ty, &nested_impl_trait_context)
             }
             FnRetTy::Default(ret_ty_span) => self.arena.alloc(self.ty_tup(*ret_ty_span, &[])),
         };
diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs
index 16b012630da..06d885a45fb 100644
--- a/compiler/rustc_ast_lowering/src/pat.rs
+++ b/compiler/rustc_ast_lowering/src/pat.rs
@@ -37,7 +37,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             qself,
                             path,
                             ParamMode::Optional,
-                            &mut ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                         );
                         let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct");
                         break hir::PatKind::TupleStruct(qpath, pats, ddpos);
@@ -53,7 +53,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             qself,
                             path,
                             ParamMode::Optional,
-                            &mut ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                         );
                         break hir::PatKind::Path(qpath);
                     }
@@ -63,7 +63,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             qself,
                             path,
                             ParamMode::Optional,
-                            &mut ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                         );
 
                         let fs = self.arena.alloc_from_iter(fields.iter().map(|f| {