Apply manual_is_variant_and to Clippy itself

clippy_lints/src/cargo/common_metadata.rs

@@ -9,7 +9,7 @@ pub(super) fn check(cx: &LateContext<'_>, metadata: &Metadata, ignore_publish: b
     for package in &metadata.packages {
         // only run the lint if publish is `None` (`publish = true` or skipped entirely)
         // or if the vector isn't empty (`publish = ["something"]`)
-        if package.publish.as_ref().filter(|publish| publish.is_empty()).is_none() || ignore_publish {
+        if package.publish.as_ref().is_none_or(|publish| !publish.is_empty()) || ignore_publish {
             if is_empty_str(package.description.as_ref()) {
                 missing_warning(cx, package, "package.description");
             }

clippy_lints/src/methods/unnecessary_to_owned.rs

@@ -702,8 +702,7 @@ fn check_if_applicable_to_argument<'tcx>(cx: &LateContext<'tcx>, arg: &Expr<'tcx
             sym::to_vec => cx
                 .tcx
                 .impl_of_assoc(method_def_id)
-                .filter(|&impl_did| cx.tcx.type_of(impl_did).instantiate_identity().is_slice())
-                .is_some(),
+                .is_some_and(|impl_did| cx.tcx.type_of(impl_did).instantiate_identity().is_slice()),
             _ => false,
         }
         && let original_arg_ty = cx.typeck_results().node_type(caller.hir_id).peel_refs()

clippy_lints/src/question_mark.rs

@@ -490,8 +490,7 @@ fn check_if_let_some_or_err_and_early_return<'tcx>(cx: &LateContext<'tcx>, expr:
             || is_early_return(sym::Result, cx, &if_block))
         && if_else
             .map(|e| eq_expr_value(cx, let_expr, peel_blocks(e)))
-            .filter(|e| *e)
-            .is_none()
+            .is_none_or(|e| !e)
     {
         if !is_copy(cx, caller_ty)
             && let Some(hir_id) = let_expr.res_local_id()