cleanup + fix warnings

Author: Jacherr

clippy_lints/src/eta_reduction.rs

@@ -196,7 +196,7 @@ fn check_clousure<'tcx>(cx: &LateContext<'tcx>, outer_receiver: Option<&Expr<'tc
             {
                 span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| {
                     if let Some(mut snippet) = snippet_opt(cx, callee.span) {
-                        if path_to_local(callee).map_or(false, |l| {
+                        if path_to_local(callee).is_some_and(|l| {
                             // FIXME: Do we really need this `local_used_in` check?
                             // Isn't it checking something like... `callee(callee)`?
                             // If somehow this check is needed, add some test for it,

clippy_lints/src/matches/single_match.rs

@@ -176,7 +176,7 @@ impl<'tcx> Visitor<'tcx> for PatVisitor<'tcx> {
         if matches!(pat.kind, PatKind::Binding(..)) {
             ControlFlow::Break(())
         } else {
-            self.has_enum |= self.typeck.pat_ty(pat).ty_adt_def().map_or(false, AdtDef::is_enum);
+            self.has_enum |= self.typeck.pat_ty(pat).ty_adt_def().is_some_and(AdtDef::is_enum);
             walk_pat(self, pat)
         }
     }

clippy_lints/src/methods/unnecessary_map_or.rs

@@ -5,8 +5,8 @@ use clippy_utils::source::{snippet, snippet_opt};
 use clippy_utils::ty::is_type_diagnostic_item;
 use clippy_utils::visitors::is_local_used;
 use clippy_utils::{get_parent_expr, is_from_proc_macro, path_to_local_id};
-use rustc_ast::util::parser::AssocOp;
 use rustc_ast::LitKind::Bool;
+use rustc_ast::util::parser::AssocOp;
 use rustc_errors::Applicability;
 use rustc_hir::{BinOpKind, Expr, ExprKind, PatKind};
 use rustc_lint::LateContext;

clippy_lints/src/redundant_slicing.rs

@@ -86,7 +86,6 @@ impl<'tcx> LateLintPass<'tcx> for RedundantSlicing {
             let (indexed_ty, indexed_ref_count) = peel_middle_ty_refs(cx.typeck_results().expr_ty(indexed));
             let parent_expr = get_parent_expr(cx, expr);
             let needs_parens_for_prefix = parent_expr.is_some_and(|parent| parent.precedence().order() > PREC_PREFIX);
-            let mut app = Applicability::MachineApplicable;
 
             if expr_ty == indexed_ty {
                 if expr_ref_count > indexed_ref_count {