Use new filter map heuristic in clippy

Author: camsteffen

clippy_lints/src/multiple_crate_versions.rs

@@ -51,7 +51,8 @@ impl LateLintPass<'_> for MultipleCrateVersions {
             if let Some(resolve) = &metadata.resolve;
             if let Some(local_id) = packages
                 .iter()
-                .find_map(|p| if p.name == *local_name { Some(&p.id) } else { None });
+                .find(|p| p.name == *local_name)
+                .map(|p| &p.id);
             then {
                 for (name, group) in &packages.iter().group_by(|p| p.name.clone()) {
                     let group: Vec<&Package> = group.collect();

clippy_lints/src/shadow.rs

@@ -203,9 +203,7 @@ fn check_pat<'tcx>(
                 if let ExprKind::Struct(_, ref efields, _) = init_struct.kind {
                     for field in pfields {
                         let name = field.ident.name;
-                        let efield = efields
-                            .iter()
-                            .find_map(|f| if f.ident.name == name { Some(&*f.expr) } else { None });
+                        let efield = efields.iter().find(|f| f.ident.name == name).map(|f| f.expr);
                         check_pat(cx, &field.pat, efield, span, bindings);
                     }
                 } else {

clippy_lints/src/suspicious_operation_groupings.rs

@@ -688,6 +688,5 @@ fn skip_index<A, Iter>(iter: Iter, index: usize) -> impl Iterator<Item = A>
 where
     Iter: Iterator<Item = A>,
 {
-    iter.enumerate()
-        .filter_map(move |(i, a)| if i == index { None } else { Some(a) })
+    iter.enumerate().filter(move |&(i, _)| i != index).map(|(_, a)| a)
 }