Rollup merge of #76995 - LingMan:middle_matches, r=varkor

Reduce boilerplate with the matches! macro

Replaces simple bool `match`es of the form

    match $expr {
        $pattern => true
        _ => false
    }

and their inverse with invocations of the matches! macro.

Limited to rustc_middle for now to get my feet wet.

Author: JohnTitor

compiler/rustc_middle/src/hir/map/mod.rs

@@ -535,15 +535,15 @@ impl<'hir> Map<'hir> {
             Some(Node::Binding(_)) => (),
             _ => return false,
         }
-        match self.find(self.get_parent_node(id)) {
+        matches!(
+            self.find(self.get_parent_node(id)),
             Some(
                 Node::Item(_)
                 | Node::TraitItem(_)
                 | Node::ImplItem(_)
                 | Node::Expr(Expr { kind: ExprKind::Closure(..), .. }),
-            ) => true,
-            _ => false,
-        }
+            )
+        )
     }
 
     /// Whether the expression pointed at by `hir_id` belongs to a `const` evaluation context.
@@ -554,10 +554,10 @@ impl<'hir> Map<'hir> {
 
     /// Whether `hir_id` corresponds to a `mod` or a crate.
     pub fn is_hir_id_module(&self, hir_id: HirId) -> bool {
-        match self.get_entry(hir_id).node {
-            Node::Item(Item { kind: ItemKind::Mod(_), .. }) | Node::Crate(..) => true,
-            _ => false,
-        }
+        matches!(
+            self.get_entry(hir_id).node,
+            Node::Item(Item { kind: ItemKind::Mod(_), .. }) | Node::Crate(..)
+        )
     }
 
     /// Retrieves the `HirId` for `id`'s enclosing method, unless there's a

compiler/rustc_middle/src/mir/interpret/mod.rs

@@ -486,10 +486,10 @@ impl<'tcx> TyCtxt<'tcx> {
         // `main as fn() == main as fn()` is false, while `let x = main as fn(); x == x` is true.
         // However, formatting code relies on function identity (see #58320), so we only do
         // this for generic functions.  Lifetime parameters are ignored.
-        let is_generic = instance.substs.into_iter().any(|kind| match kind.unpack() {
-            GenericArgKind::Lifetime(_) => false,
-            _ => true,
-        });
+        let is_generic = instance
+            .substs
+            .into_iter()
+            .any(|kind| !matches!(kind.unpack(), GenericArgKind::Lifetime(_)));
         if is_generic {
             // Get a fresh ID.
             let mut alloc_map = self.alloc_map.lock();

compiler/rustc_middle/src/mir/interpret/value.rs

@@ -445,19 +445,13 @@ impl<'tcx, Tag> Scalar<Tag> {
     /// Do not call this method!  Dispatch based on the type instead.
     #[inline]
     pub fn is_bits(self) -> bool {
-        match self {
-            Scalar::Raw { .. } => true,
-            _ => false,
-        }
+        matches!(self, Scalar::Raw { .. })
     }
 
     /// Do not call this method!  Dispatch based on the type instead.
     #[inline]
     pub fn is_ptr(self) -> bool {
-        match self {
-            Scalar::Ptr(_) => true,
-            _ => false,
-        }
+        matches!(self, Scalar::Ptr(_))
     }
 
     pub fn to_bool(self) -> InterpResult<'tcx, bool> {

compiler/rustc_middle/src/mir/mod.rs

@@ -971,67 +971,59 @@ impl<'tcx> LocalDecl<'tcx> {
     /// - `let x = ...`,
     /// - or `match ... { C(x) => ... }`
     pub fn can_be_made_mutable(&self) -> bool {
-        match self.local_info {
-            Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
-                binding_mode: ty::BindingMode::BindByValue(_),
-                opt_ty_info: _,
-                opt_match_place: _,
-                pat_span: _,
-            })))) => true,
-
-            Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(
-                ImplicitSelfKind::Imm,
-            )))) => true,
-
-            _ => false,
-        }
+        matches!(
+            self.local_info,
+            Some(box LocalInfo::User(ClearCrossCrate::Set(
+                BindingForm::Var(VarBindingForm {
+                    binding_mode: ty::BindingMode::BindByValue(_),
+                    opt_ty_info: _,
+                    opt_match_place: _,
+                    pat_span: _,
+                })
+                | BindingForm::ImplicitSelf(ImplicitSelfKind::Imm),
+            )))
+        )
     }
 
     /// Returns `true` if local is definitely not a `ref ident` or
     /// `ref mut ident` binding. (Such bindings cannot be made into
     /// mutable bindings, but the inverse does not necessarily hold).
     pub fn is_nonref_binding(&self) -> bool {
-        match self.local_info {
-            Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
-                binding_mode: ty::BindingMode::BindByValue(_),
-                opt_ty_info: _,
-                opt_match_place: _,
-                pat_span: _,
-            })))) => true,
-
-            Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(_)))) => true,
-
-            _ => false,
-        }
+        matches!(
+            self.local_info,
+            Some(box LocalInfo::User(ClearCrossCrate::Set(
+                BindingForm::Var(VarBindingForm {
+                    binding_mode: ty::BindingMode::BindByValue(_),
+                    opt_ty_info: _,
+                    opt_match_place: _,
+                    pat_span: _,
+                })
+                | BindingForm::ImplicitSelf(_),
+            )))
+        )
     }
 
     /// Returns `true` if this variable is a named variable or function
     /// parameter declared by the user.
     #[inline]
     pub fn is_user_variable(&self) -> bool {
-        match self.local_info {
-            Some(box LocalInfo::User(_)) => true,
-            _ => false,
-        }
+        matches!(self.local_info, Some(box LocalInfo::User(_)))
     }
 
     /// Returns `true` if this is a reference to a variable bound in a `match`
     /// expression that is used to access said variable for the guard of the
     /// match arm.
     pub fn is_ref_for_guard(&self) -> bool {
-        match self.local_info {
-            Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard))) => true,
-            _ => false,
-        }
+        matches!(
+            self.local_info,
+            Some(box LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard)))
+        )
     }
 
     /// Returns `Some` if this is a reference to a static item that is used to
     /// access that static
     pub fn is_ref_to_static(&self) -> bool {
-        match self.local_info {
-            Some(box LocalInfo::StaticRef { .. }) => true,
-            _ => false,
-        }
+        matches!(self.local_info, Some(box LocalInfo::StaticRef { .. }))
     }
 
     /// Returns `Some` if this is a reference to a static item that is used to
@@ -2164,10 +2156,7 @@ pub enum BinOp {
 impl BinOp {
     pub fn is_checkable(self) -> bool {
         use self::BinOp::*;
-        match self {
-            Add | Sub | Mul | Shl | Shr => true,
-            _ => false,
-        }
+        matches!(self, Add | Sub | Mul | Shl | Shr)
     }
 }
 

compiler/rustc_middle/src/mir/visit.rs

@@ -1164,82 +1164,63 @@ pub enum PlaceContext {
 impl PlaceContext {
     /// Returns `true` if this place context represents a drop.
     pub fn is_drop(&self) -> bool {
-        match *self {
-            PlaceContext::MutatingUse(MutatingUseContext::Drop) => true,
-            _ => false,
-        }
+        matches!(self, PlaceContext::MutatingUse(MutatingUseContext::Drop))
     }
 
     /// Returns `true` if this place context represents a borrow.
     pub fn is_borrow(&self) -> bool {
-        match *self {
+        matches!(
+            self,
             PlaceContext::NonMutatingUse(
                 NonMutatingUseContext::SharedBorrow
-                | NonMutatingUseContext::ShallowBorrow
-                | NonMutatingUseContext::UniqueBorrow,
-            )
-            | PlaceContext::MutatingUse(MutatingUseContext::Borrow) => true,
-            _ => false,
-        }
+                    | NonMutatingUseContext::ShallowBorrow
+                    | NonMutatingUseContext::UniqueBorrow
+            ) | PlaceContext::MutatingUse(MutatingUseContext::Borrow)
+        )
     }
 
     /// Returns `true` if this place context represents a storage live or storage dead marker.
     pub fn is_storage_marker(&self) -> bool {
-        match *self {
-            PlaceContext::NonUse(NonUseContext::StorageLive | NonUseContext::StorageDead) => true,
-            _ => false,
-        }
+        matches!(
+            self,
+            PlaceContext::NonUse(NonUseContext::StorageLive | NonUseContext::StorageDead)
+        )
     }
 
     /// Returns `true` if this place context represents a storage live marker.
     pub fn is_storage_live_marker(&self) -> bool {
-        match *self {
-            PlaceContext::NonUse(NonUseContext::StorageLive) => true,
-            _ => false,
-        }
+        matches!(self, PlaceContext::NonUse(NonUseContext::StorageLive))
     }
 
     /// Returns `true` if this place context represents a storage dead marker.
     pub fn is_storage_dead_marker(&self) -> bool {
-        match *self {
-            PlaceContext::NonUse(NonUseContext::StorageDead) => true,
-            _ => false,
-        }
+        matches!(self, PlaceContext::NonUse(NonUseContext::StorageDead))
     }
 
     /// Returns `true` if this place context represents a use that potentially changes the value.
     pub fn is_mutating_use(&self) -> bool {
-        match *self {
-            PlaceContext::MutatingUse(..) => true,
-            _ => false,
-        }
+        matches!(self, PlaceContext::MutatingUse(..))
     }
 
     /// Returns `true` if this place context represents a use that does not change the value.
     pub fn is_nonmutating_use(&self) -> bool {
-        match *self {
-            PlaceContext::NonMutatingUse(..) => true,
-            _ => false,
-        }
+        matches!(self, PlaceContext::NonMutatingUse(..))
     }
 
     /// Returns `true` if this place context represents a use.
     pub fn is_use(&self) -> bool {
-        match *self {
-            PlaceContext::NonUse(..) => false,
-            _ => true,
-        }
+        !matches!(self, PlaceContext::NonUse(..))
     }
 
     /// Returns `true` if this place context represents an assignment statement.
     pub fn is_place_assignment(&self) -> bool {
-        match *self {
+        matches!(
+            self,
             PlaceContext::MutatingUse(
                 MutatingUseContext::Store
-                | MutatingUseContext::Call
-                | MutatingUseContext::AsmOutput,
-            ) => true,
-            _ => false,
-        }
+                    | MutatingUseContext::Call
+                    | MutatingUseContext::AsmOutput,
+            )
+        )
     }
 }

compiler/rustc_middle/src/traits/specialization_graph.rs

@@ -79,10 +79,7 @@ pub enum Node {
 
 impl<'tcx> Node {
     pub fn is_from_trait(&self) -> bool {
-        match *self {
-            Node::Trait(..) => true,
-            _ => false,
-        }
+        matches!(self, Node::Trait(..))
     }
 
     /// Iterate over the items defined directly by the given (impl or trait) node.

compiler/rustc_middle/src/ty/adjustment.rs

@@ -85,10 +85,7 @@ pub struct Adjustment<'tcx> {
 
 impl Adjustment<'tcx> {
     pub fn is_region_borrow(&self) -> bool {
-        match self.kind {
-            Adjust::Borrow(AutoBorrow::Ref(..)) => true,
-            _ => false,
-        }
+        matches!(self.kind, Adjust::Borrow(AutoBorrow::Ref(..)))
     }
 }
 

compiler/rustc_middle/src/ty/context.rs

@@ -588,10 +588,7 @@ impl<'tcx> TypeckResults<'tcx> {
             return false;
         }
 
-        match self.type_dependent_defs().get(expr.hir_id) {
-            Some(Ok((DefKind::AssocFn, _))) => true,
-            _ => false,
-        }
+        matches!(self.type_dependent_defs().get(expr.hir_id), Some(Ok((DefKind::AssocFn, _))))
     }
 
     pub fn extract_binding_mode(&self, s: &Session, id: HirId, sp: Span) -> Option<BindingMode> {

compiler/rustc_middle/src/ty/diagnostics.rs

@@ -11,21 +11,16 @@ use rustc_hir::{QPath, TyKind, WhereBoundPredicate, WherePredicate};
 impl<'tcx> TyS<'tcx> {
     /// Similar to `TyS::is_primitive`, but also considers inferred numeric values to be primitive.
     pub fn is_primitive_ty(&self) -> bool {
-        match self.kind() {
-            Bool
-            | Char
-            | Str
-            | Int(_)
-            | Uint(_)
-            | Float(_)
+        matches!(
+            self.kind(),
+            Bool | Char | Str | Int(_) | Uint(_) | Float(_)
             | Infer(
                 InferTy::IntVar(_)
                 | InferTy::FloatVar(_)
                 | InferTy::FreshIntTy(_)
-                | InferTy::FreshFloatTy(_),
-            ) => true,
-            _ => false,
-        }
+                | InferTy::FreshFloatTy(_)
+            )
+        )
     }
 
     /// Whether the type is succinctly representable as a type instead of just referred to with a
@@ -64,11 +59,16 @@ impl<'tcx> TyS<'tcx> {
 
     /// Whether the type can be safely suggested during error recovery.
     pub fn is_suggestable(&self) -> bool {
-        match self.kind() {
-            Opaque(..) | FnDef(..) | FnPtr(..) | Dynamic(..) | Closure(..) | Infer(..)
-            | Projection(..) => false,
-            _ => true,
-        }
+        !matches!(
+            self.kind(),
+            Opaque(..)
+                | FnDef(..)
+                | FnPtr(..)
+                | Dynamic(..)
+                | Closure(..)
+                | Infer(..)
+                | Projection(..)
+        )
     }
 }
 

compiler/rustc_middle/src/ty/instance.rs

@@ -184,10 +184,10 @@ impl<'tcx> InstanceDef<'tcx> {
             ty::InstanceDef::DropGlue(_, Some(_)) => return false,
             _ => return true,
         };
-        match tcx.def_key(def_id).disambiguated_data.data {
-            DefPathData::Ctor | DefPathData::ClosureExpr => true,
-            _ => false,
-        }
+        matches!(
+            tcx.def_key(def_id).disambiguated_data.data,
+            DefPathData::Ctor | DefPathData::ClosureExpr
+        )
     }
 
     /// Returns `true` if the machine code for this instance is instantiated in