fix a couple of stylistic clippy warnings

namely:

clippy::redundant_pattern_matching
clippy::redundant_pattern
clippy::search_is_some
clippy::filter_next
clippy::into_iter_on_ref
clippy::clone_on_copy
clippy::needless_return

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/named_anon_conflict.rs

@@ -85,7 +85,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
 
                 debug!("try_report_named_anon_conflict: ret ty {:?}", ty);
                 if sub == &ty::ReStatic
-                    && v.0.into_iter().find(|t| t.span.desugaring_kind().is_none()).is_some()
+                    && v.0.into_iter().any(|t| t.span.desugaring_kind().is_none())
                 {
                     // If the failure is due to a `'static` requirement coming from a `dyn` or
                     // `impl` Trait that *isn't* caused by `async fn` desugaring, handle this case

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -273,10 +273,10 @@ pub trait PrettyPrinter<'tcx>:
         }
 
         match self.tcx().trimmed_def_paths(LOCAL_CRATE).get(&def_id) {
-            None => return Ok((self, false)),
+            None => Ok((self, false)),
             Some(symbol) => {
                 self.write_str(&symbol.as_str())?;
-                return Ok((self, true));
+                Ok((self, true))
             }
         }
     }

compiler/rustc_mir/src/borrow_check/diagnostics/region_errors.rs

@@ -387,7 +387,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         if let ReturnConstraint::ClosureUpvar(upvar) = kind {
             let def_id = match self.regioncx.universal_regions().defining_ty {
                 DefiningTy::Closure(def_id, _) => def_id,
-                ty @ _ => bug!("unexpected DefiningTy {:?}", ty),
+                ty => bug!("unexpected DefiningTy {:?}", ty),
             };
 
             let upvar_def_span = self.infcx.tcx.hir().span(upvar);

compiler/rustc_mir/src/transform/instcombine.rs

@@ -126,7 +126,7 @@ impl OptimizationFinder<'b, 'tcx> {
             }
         }
 
-        return None;
+        None
     }
 }
 

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1534,7 +1534,7 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
             }
         };
 
-        let lifetime_names: Vec<_> = lifetime_names.into_iter().collect();
+        let lifetime_names: Vec<_> = lifetime_names.iter().collect();
         match (&lifetime_names[..], snippet.as_deref()) {
             ([name], Some("&")) => {
                 suggest_existing(err, &name.as_str()[..], &|name| format!("&{} ", name));

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -182,7 +182,7 @@ fn overlap_within_probe(
     }
 
     if !skip_leak_check.is_yes() {
-        if let Err(_) = infcx.leak_check(true, snapshot) {
+        if infcx.leak_check(true, snapshot).is_err() {
             debug!("overlap: leak check failed");
             return None;
         }

compiler/rustc_typeck/src/check/_match.rs

@@ -164,7 +164,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                     // If all the obligations hold (or there are no obligations) the tail expression
                     // we can suggest to return a boxed trait object instead of an opaque type.
-                    if suggest_box { self.ret_type_span.clone() } else { None }
+                    if suggest_box { self.ret_type_span } else { None }
                 }
                 _ => None,
             };

compiler/rustc_typeck/src/check/expr.rs

@@ -1243,10 +1243,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         } else if check_completeness && !error_happened && !remaining_fields.is_empty() {
             let no_accessible_remaining_fields = remaining_fields
                 .iter()
-                .filter(|(_, (_, field))| {
+                .find(|(_, (_, field))| {
                     field.vis.is_accessible_from(tcx.parent_module(expr_id).to_def_id(), tcx)
                 })
-                .next()
                 .is_none();
 
             if no_accessible_remaining_fields {

compiler/rustc_typeck/src/check/pat.rs

@@ -1141,10 +1141,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         } else if !etc && !unmentioned_fields.is_empty() {
             let no_accessible_unmentioned_fields = unmentioned_fields
                 .iter()
-                .filter(|(field, _)| {
+                .find(|(field, _)| {
                     field.vis.is_accessible_from(tcx.parent_module(pat.hir_id).to_def_id(), tcx)
                 })
-                .next()
                 .is_none();
 
             if no_accessible_unmentioned_fields {