From ed7e438f87a6b2b036db06608d23f23b50d54d6c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matthias=20Kr=C3=BCger?= <matthias.krueger@famsik.de>
Date: Sat, 6 Nov 2021 16:36:23 +0100
Subject: [PATCH] use filter(|x| matches!(..)) instead of filter_map(|x| match
 x ... => Some(xy))

---
 compiler/rustc_resolve/src/late/lifetimes.rs  | 28 ++++++-------------
 .../rustc_typeck/src/coherence/builtin.rs     |  8 +++---
 2 files changed, 12 insertions(+), 24 deletions(-)

diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs
index 94563400a8b53..1ed264b2c95f9 100644
--- a/compiler/rustc_resolve/src/late/lifetimes.rs
+++ b/compiler/rustc_resolve/src/late/lifetimes.rs
@@ -887,10 +887,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
                 let (lifetimes, binders): (FxIndexMap<hir::ParamName, Region>, Vec<_>) = c
                     .generic_params
                     .iter()
-                    .filter_map(|param| match param.kind {
-                        GenericParamKind::Lifetime { .. } => Some(param),
-                        _ => None,
-                    })
+                    .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. }))
                     .enumerate()
                     .map(|(late_bound_idx, param)| {
                         let pair = Region::late(late_bound_idx as u32, &self.tcx.hir(), param);
@@ -1370,9 +1367,8 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
                         let (lifetimes, binders): (FxIndexMap<hir::ParamName, Region>, Vec<_>) =
                             bound_generic_params
                                 .iter()
-                                .filter_map(|param| match param.kind {
-                                    GenericParamKind::Lifetime { .. } => Some(param),
-                                    _ => None,
+                                .filter(|param| {
+                                    matches!(param.kind, GenericParamKind::Lifetime { .. })
                                 })
                                 .enumerate()
                                 .map(|(late_bound_idx, param)| {
@@ -1469,10 +1465,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
         let binders_iter = trait_ref
             .bound_generic_params
             .iter()
-            .filter_map(|param| match param.kind {
-                GenericParamKind::Lifetime { .. } => Some(param),
-                _ => None,
-            })
+            .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. }))
             .enumerate()
             .map(|(late_bound_idx, param)| {
                 let pair = Region::late(
@@ -2237,19 +2230,14 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
         let binders: Vec<_> = generics
             .params
             .iter()
-            .filter_map(|param| match param.kind {
-                GenericParamKind::Lifetime { .. }
-                    if self.map.late_bound.contains(&param.hir_id) =>
-                {
-                    Some(param)
-                }
-                _ => None,
+            .filter(|param| {
+                matches!(param.kind, GenericParamKind::Lifetime { .. })
+                    && self.map.late_bound.contains(&param.hir_id)
             })
             .enumerate()
             .map(|(late_bound_idx, param)| {
                 let pair = Region::late(late_bound_idx as u32, &self.tcx.hir(), param);
-                let r = late_region_as_bound_region(self.tcx, &pair.1);
-                r
+                late_region_as_bound_region(self.tcx, &pair.1)
             })
             .collect();
         self.map.late_bound_vars.insert(hir_id, binders);
diff --git a/compiler/rustc_typeck/src/coherence/builtin.rs b/compiler/rustc_typeck/src/coherence/builtin.rs
index 8cae61e8c22f6..d818771f7800a 100644
--- a/compiler/rustc_typeck/src/coherence/builtin.rs
+++ b/compiler/rustc_typeck/src/coherence/builtin.rs
@@ -180,14 +180,14 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
 
                 let coerced_fields = fields
                     .iter()
-                    .filter_map(|field| {
+                    .filter(|field| {
                         let ty_a = field.ty(tcx, substs_a);
                         let ty_b = field.ty(tcx, substs_b);
 
                         if let Ok(layout) = tcx.layout_of(param_env.and(ty_a)) {
                             if layout.is_zst() && layout.align.abi.bytes() == 1 {
                                 // ignore ZST fields with alignment of 1 byte
-                                return None;
+                                return false;
                             }
                         }
 
@@ -204,11 +204,11 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
                                 ))
                                 .emit();
 
-                                return None;
+                                return false;
                             }
                         }
 
-                        Some(field)
+                        return true;
                     })
                     .collect::<Vec<_>>();