Rollup merge of #80344 - matthiaskrgr:matches, r=Dylan-DPC

use matches!() macro in more places

compiler/rustc_ast/src/ast.rs

@@ -167,10 +167,7 @@ pub enum GenericArgs {
 
 impl GenericArgs {
     pub fn is_angle_bracketed(&self) -> bool {
-        match *self {
-            AngleBracketed(..) => true,
-            _ => false,
-        }
+        matches!(self, AngleBracketed(..))
     }
 
     pub fn span(&self) -> Span {
@@ -629,10 +626,7 @@ impl Pat {
 
     /// Is this a `..` pattern?
     pub fn is_rest(&self) -> bool {
-        match self.kind {
-            PatKind::Rest => true,
-            _ => false,
-        }
+        matches!(self.kind, PatKind::Rest)
     }
 }
 
@@ -852,10 +846,7 @@ impl BinOpKind {
         }
     }
     pub fn lazy(&self) -> bool {
-        match *self {
-            BinOpKind::And | BinOpKind::Or => true,
-            _ => false,
-        }
+        matches!(self, BinOpKind::And | BinOpKind::Or)
     }
 
     pub fn is_comparison(&self) -> bool {
@@ -963,17 +954,11 @@ impl Stmt {
     }
 
     pub fn is_item(&self) -> bool {
-        match self.kind {
-            StmtKind::Item(_) => true,
-            _ => false,
-        }
+        matches!(self.kind, StmtKind::Item(_))
     }
 
     pub fn is_expr(&self) -> bool {
-        match self.kind {
-            StmtKind::Expr(_) => true,
-            _ => false,
-        }
+        matches!(self.kind, StmtKind::Expr(_))
     }
 }
 
@@ -1652,26 +1637,17 @@ pub enum LitKind {
 impl LitKind {
     /// Returns `true` if this literal is a string.
     pub fn is_str(&self) -> bool {
-        match *self {
-            LitKind::Str(..) => true,
-            _ => false,
-        }
+        matches!(self, LitKind::Str(..))
     }
 
     /// Returns `true` if this literal is byte literal string.
     pub fn is_bytestr(&self) -> bool {
-        match self {
-            LitKind::ByteStr(_) => true,
-            _ => false,
-        }
+        matches!(self, LitKind::ByteStr(_))
     }
 
     /// Returns `true` if this is a numeric literal.
     pub fn is_numeric(&self) -> bool {
-        match *self {
-            LitKind::Int(..) | LitKind::Float(..) => true,
-            _ => false,
-        }
+        matches!(self, LitKind::Int(..) | LitKind::Float(..))
     }
 
     /// Returns `true` if this literal has no suffix.
@@ -2237,10 +2213,7 @@ impl FnDecl {
         self.inputs.get(0).map_or(false, Param::is_self)
     }
     pub fn c_variadic(&self) -> bool {
-        self.inputs.last().map_or(false, |arg| match arg.ty.kind {
-            TyKind::CVarArgs => true,
-            _ => false,
-        })
+        self.inputs.last().map_or(false, |arg| matches!(arg.ty.kind, TyKind::CVarArgs))
     }
 }
 

compiler/rustc_ast/src/attr/mod.rs

@@ -234,10 +234,7 @@ impl MetaItem {
     }
 
     pub fn is_word(&self) -> bool {
-        match self.kind {
-            MetaItemKind::Word => true,
-            _ => false,
-        }
+        matches!(self.kind, MetaItemKind::Word)
     }
 
     pub fn has_name(&self, name: Symbol) -> bool {

compiler/rustc_ast/src/token.rs

@@ -130,10 +130,7 @@ impl LitKind {
     }
 
     crate fn may_have_suffix(self) -> bool {
-        match self {
-            Integer | Float | Err => true,
-            _ => false,
-        }
+        matches!(self, Integer | Float | Err)
     }
 }
 
@@ -305,10 +302,7 @@ impl TokenKind {
     }
 
     pub fn should_end_const_arg(&self) -> bool {
-        match self {
-            Gt | Ge | BinOp(Shr) | BinOpEq(Shr) => true,
-            _ => false,
-        }
+        matches!(self, Gt | Ge | BinOp(Shr) | BinOpEq(Shr))
     }
 }
 
@@ -346,18 +340,21 @@ impl Token {
     }
 
     pub fn is_op(&self) -> bool {
-        match self.kind {
-            OpenDelim(..) | CloseDelim(..) | Literal(..) | DocComment(..) | Ident(..)
-            | Lifetime(..) | Interpolated(..) | Eof => false,
-            _ => true,
-        }
+        !matches!(
+            self.kind,
+            OpenDelim(..)
+                | CloseDelim(..)
+                | Literal(..)
+                | DocComment(..)
+                | Ident(..)
+                | Lifetime(..)
+                | Interpolated(..)
+                | Eof
+        )
     }
 
     pub fn is_like_plus(&self) -> bool {
-        match self.kind {
-            BinOp(Plus) | BinOpEq(Plus) => true,
-            _ => false,
-        }
+        matches!(self.kind, BinOp(Plus) | BinOpEq(Plus))
     }
 
     /// Returns `true` if the token can appear at the start of an expression.
@@ -379,13 +376,10 @@ impl Token {
             ModSep                            | // global path
             Lifetime(..)                      | // labeled loop
             Pound                             => true, // expression attributes
-            Interpolated(ref nt) => match **nt {
-                NtLiteral(..) |
+            Interpolated(ref nt) => matches!(**nt, NtLiteral(..) |
                 NtExpr(..)    |
                 NtBlock(..)   |
-                NtPath(..) => true,
-                _ => false,
-            },
+                NtPath(..)),
             _ => false,
         }
     }
@@ -405,10 +399,7 @@ impl Token {
             Lifetime(..)                | // lifetime bound in trait object
             Lt | BinOp(Shl)             | // associated path
             ModSep                      => true, // global path
-            Interpolated(ref nt) => match **nt {
-                NtTy(..) | NtPath(..) => true,
-                _ => false,
-            },
+            Interpolated(ref nt) => matches!(**nt, NtTy(..) | NtPath(..)),
             _ => false,
         }
     }
@@ -417,10 +408,7 @@ impl Token {
     pub fn can_begin_const_arg(&self) -> bool {
         match self.kind {
             OpenDelim(Brace) => true,
-            Interpolated(ref nt) => match **nt {
-                NtExpr(..) | NtBlock(..) | NtLiteral(..) => true,
-                _ => false,
-            },
+            Interpolated(ref nt) => matches!(**nt, NtExpr(..) | NtBlock(..) | NtLiteral(..)),
             _ => self.can_begin_literal_maybe_minus(),
         }
     }
@@ -436,10 +424,7 @@ impl Token {
 
     /// Returns `true` if the token is any literal.
     pub fn is_lit(&self) -> bool {
-        match self.kind {
-            Literal(..) => true,
-            _ => false,
-        }
+        matches!(self.kind, Literal(..))
     }
 
     /// Returns `true` if the token is any literal, a minus (which can prefix a literal,

compiler/rustc_ast/src/util/classify.rs

@@ -12,14 +12,14 @@ use crate::ast;
 ///      |x| 5
 /// isn't parsed as (if true {...} else {...} | x) | 5
 pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool {
-    match e.kind {
+    !matches!(
+        e.kind,
         ast::ExprKind::If(..)
-        | ast::ExprKind::Match(..)
-        | ast::ExprKind::Block(..)
-        | ast::ExprKind::While(..)
-        | ast::ExprKind::Loop(..)
-        | ast::ExprKind::ForLoop(..)
-        | ast::ExprKind::TryBlock(..) => false,
-        _ => true,
-    }
+            | ast::ExprKind::Match(..)
+            | ast::ExprKind::Block(..)
+            | ast::ExprKind::While(..)
+            | ast::ExprKind::Loop(..)
+            | ast::ExprKind::ForLoop(..)
+            | ast::ExprKind::TryBlock(..)
+    )
 }

compiler/rustc_ast/src/util/comments.rs

@@ -180,10 +180,8 @@ pub fn gather_comments(sm: &SourceMap, path: FileName, src: String) -> Vec<Comme
             }
             rustc_lexer::TokenKind::BlockComment { doc_style, .. } => {
                 if doc_style.is_none() {
-                    let code_to_the_right = match text[pos + token.len..].chars().next() {
-                        Some('\r' | '\n') => false,
-                        _ => true,
-                    };
+                    let code_to_the_right =
+                        !matches!(text[pos + token.len..].chars().next(), Some('\r' | '\n'));
                     let style = match (code_to_the_left, code_to_the_right) {
                         (_, true) => CommentStyle::Mixed,
                         (false, false) => CommentStyle::Isolated,

compiler/rustc_builtin_macros/src/deriving/clone.rs

@@ -38,10 +38,9 @@ pub fn expand_deriving_clone(
             | ItemKind::Enum(_, Generics { ref params, .. }) => {
                 let container_id = cx.current_expansion.id.expn_data().parent;
                 if cx.resolver.has_derive_copy(container_id)
-                    && !params.iter().any(|param| match param.kind {
-                        ast::GenericParamKind::Type { .. } => true,
-                        _ => false,
-                    })
+                    && !params
+                        .iter()
+                        .any(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }))
                 {
                     bounds = vec![];
                     is_shallow = true;

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -404,12 +404,10 @@ impl<'a> TraitDef<'a> {
                 let has_no_type_params = match item.kind {
                     ast::ItemKind::Struct(_, ref generics)
                     | ast::ItemKind::Enum(_, ref generics)
-                    | ast::ItemKind::Union(_, ref generics) => {
-                        !generics.params.iter().any(|param| match param.kind {
-                            ast::GenericParamKind::Type { .. } => true,
-                            _ => false,
-                        })
-                    }
+                    | ast::ItemKind::Union(_, ref generics) => !generics
+                        .params
+                        .iter()
+                        .any(|param| matches!(param.kind, ast::GenericParamKind::Type { .. })),
                     _ => unreachable!(),
                 };
                 let container_id = cx.current_expansion.id.expn_data().parent;
@@ -868,7 +866,7 @@ impl<'a> MethodDef<'a> {
                 Self_ if nonstatic => {
                     self_args.push(arg_expr);
                 }
-                Ptr(ref ty, _) if (if let Self_ = **ty { true } else { false }) && nonstatic => {
+                Ptr(ref ty, _) if matches!(**ty, Self_) && nonstatic => {
                     self_args.push(cx.expr_deref(trait_.span, arg_expr))
                 }
                 _ => {

compiler/rustc_builtin_macros/src/format.rs

@@ -1044,10 +1044,7 @@ pub fn expand_preparsed_format_args(
 
     let numbered_position_args = pieces.iter().any(|arg: &parse::Piece<'_>| match *arg {
         parse::String(_) => false,
-        parse::NextArgument(arg) => match arg.position {
-            parse::Position::ArgumentIs(_) => true,
-            _ => false,
-        },
+        parse::NextArgument(arg) => matches!(arg.position, parse::Position::ArgumentIs(_)),
     });
 
     cx.build_index_map();

compiler/rustc_builtin_macros/src/format_foreign.rs

@@ -580,10 +580,7 @@ pub mod printf {
     }
 
     fn is_flag(c: &char) -> bool {
-        match c {
-            '0' | '-' | '+' | ' ' | '#' | '\'' => true,
-            _ => false,
-        }
+        matches!(c, '0' | '-' | '+' | ' ' | '#' | '\'')
     }
 
     #[cfg(test)]

compiler/rustc_builtin_macros/src/llvm_asm.rs

@@ -87,9 +87,11 @@ fn parse_inline_asm<'a>(
     // parsed as `llvm_asm!(z)` with `z = "x": y` which is type ascription.
     let first_colon = tts
         .trees()
-        .position(|tt| match tt {
-            tokenstream::TokenTree::Token(Token { kind: token::Colon | token::ModSep, .. }) => true,
-            _ => false,
+        .position(|tt| {
+            matches!(
+                tt,
+                tokenstream::TokenTree::Token(Token { kind: token::Colon | token::ModSep, .. })
+            )
         })
         .unwrap_or(tts.len());
     let mut p = cx.new_parser_from_tts(tts.trees().skip(first_colon).collect());

compiler/rustc_builtin_macros/src/proc_macro_harness.rs

@@ -256,10 +256,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
         // we're just not interested in this item.
         //
         // If we find one, try to locate a `#[proc_macro_derive]` attribute on it.
-        let is_fn = match item.kind {
-            ast::ItemKind::Fn(..) => true,
-            _ => false,
-        };
+        let is_fn = matches!(item.kind, ast::ItemKind::Fn(..));
 
         let mut found_attr: Option<&'a ast::Attribute> = None;
 

compiler/rustc_codegen_ssa/src/mir/analyze.rs

@@ -112,12 +112,12 @@ impl<Bx: BuilderMethods<'a, 'tcx>> LocalAnalyzer<'mir, 'a, 'tcx, Bx> {
             };
 
             // Allow uses of projections that are ZSTs or from scalar fields.
-            let is_consume = match context {
+            let is_consume = matches!(
+                context,
                 PlaceContext::NonMutatingUse(
                     NonMutatingUseContext::Copy | NonMutatingUseContext::Move,
-                ) => true,
-                _ => false,
-            };
+                )
+            );
             if is_consume {
                 let base_ty =
                     mir::Place::ty_from(place_ref.local, proj_base, self.fx.mir, cx.tcx());

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

@@ -132,10 +132,7 @@ impl Visitor<'tcx> for TypeParamSpanVisitor<'tcx> {
                 [segment]
                     if segment
                         .res
-                        .map(|res| match res {
-                            Res::SelfTy(_, _) | Res::Def(hir::def::DefKind::TyParam, _) => true,
-                            _ => false,
-                        })
+                        .map(|res| matches!(res, Res::SelfTy(_, _) | Res::Def(hir::def::DefKind::TyParam, _)))
                         .unwrap_or(false) =>
                 {
                     self.types.push(path.span);

compiler/rustc_infer/src/infer/free_regions.rs

@@ -93,10 +93,7 @@ impl<'tcx> FreeRegionMap<'tcx> {
 
     /// True for free regions other than `'static`.
     pub fn is_free(&self, r: Region<'_>) -> bool {
-        match *r {
-            ty::ReEarlyBound(_) | ty::ReFree(_) => true,
-            _ => false,
-        }
+        matches!(r, ty::ReEarlyBound(_) | ty::ReFree(_))
     }
 
     /// True if `r` is a free region or static of the sort that this

compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs

@@ -393,10 +393,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
                 if self.expand_node(a_region, b_vid, b_data) {
                     changes.push(b_vid);
                 }
-                match *b_data {
-                    VarValue::Value(ReStatic) | VarValue::ErrorValue => false,
-                    _ => true,
-                }
+                !matches!(b_data, VarValue::Value(ReStatic) | VarValue::ErrorValue)
             });
         }
     }
@@ -972,11 +969,7 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
             }
 
             VerifyBound::IsEmpty => {
-                if let ty::ReEmpty(_) = min {
-                    true
-                } else {
-                    false
-                }
+                matches!(min, ty::ReEmpty(_))
             }
 
             VerifyBound::AnyBound(bs) => {

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

@@ -42,37 +42,25 @@ trait MaybeFnLike {
 
 impl MaybeFnLike for hir::Item<'_> {
     fn is_fn_like(&self) -> bool {
-        match self.kind {
-            hir::ItemKind::Fn(..) => true,
-            _ => false,
-        }
+        matches!(self.kind, hir::ItemKind::Fn(..))
     }
 }
 
 impl MaybeFnLike for hir::ImplItem<'_> {
     fn is_fn_like(&self) -> bool {
-        match self.kind {
-            hir::ImplItemKind::Fn(..) => true,
-            _ => false,
-        }
+        matches!(self.kind, hir::ImplItemKind::Fn(..))
     }
 }
 
 impl MaybeFnLike for hir::TraitItem<'_> {
     fn is_fn_like(&self) -> bool {
-        match self.kind {
-            hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)) => true,
-            _ => false,
-        }
+        matches!(self.kind, hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)))
     }
 }
 
 impl MaybeFnLike for hir::Expr<'_> {
     fn is_fn_like(&self) -> bool {
-        match self.kind {
-            hir::ExprKind::Closure(..) => true,
-            _ => false,
-        }
+        matches!(self.kind, hir::ExprKind::Closure(..))
     }
 }
 

compiler/rustc_middle/src/mir/coverage.rs

@@ -118,17 +118,11 @@ impl CoverageKind {
     }
 
     pub fn is_counter(&self) -> bool {
-        match self {
-            Self::Counter { .. } => true,
-            _ => false,
-        }
+        matches!(self, Self::Counter { .. })
     }
 
     pub fn is_expression(&self) -> bool {
-        match self {
-            Self::Expression { .. } => true,
-            _ => false,
-        }
+        matches!(self, Self::Expression { .. })
     }
 
     pub fn is_unreachable(&self) -> bool {

compiler/rustc_middle/src/ty/error.rs

@@ -647,14 +647,11 @@ impl<T> Trait<T> for X {
         let current_method_ident = body_owner.and_then(|n| n.ident()).map(|i| i.name);
 
         // We don't want to suggest calling an assoc fn in a scope where that isn't feasible.
-        let callable_scope = match body_owner {
-            Some(
+        let callable_scope = matches!(body_owner, Some(
                 hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(..), .. })
                 | hir::Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Fn(..), .. })
                 | hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }),
-            ) => true,
-            _ => false,
-        };
+            ));
         let impl_comparison = matches!(
             cause_code,
             ObligationCauseCode::CompareImplMethodObligation { .. }

compiler/rustc_mir_build/src/build/expr/into.rs

@@ -40,11 +40,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let expr_span = expr.span;
         let source_info = this.source_info(expr_span);
 
-        let expr_is_block_or_scope = match expr.kind {
-            ExprKind::Block { .. } => true,
-            ExprKind::Scope { .. } => true,
-            _ => false,
-        };
+        let expr_is_block_or_scope = matches!(expr.kind, ExprKind::Block { .. } | ExprKind::Scope { .. });
 
         let schedule_drop = move |this: &mut Self| {
             if let Some(drop_scope) = scope {

compiler/rustc_parse/src/parser/path.rs

@@ -501,10 +501,9 @@ impl<'a> Parser<'a> {
     pub(super) fn expr_is_valid_const_arg(&self, expr: &P<rustc_ast::Expr>) -> bool {
         match &expr.kind {
             ast::ExprKind::Block(_, _) | ast::ExprKind::Lit(_) => true,
-            ast::ExprKind::Unary(ast::UnOp::Neg, expr) => match &expr.kind {
-                ast::ExprKind::Lit(_) => true,
-                _ => false,
-            },
+            ast::ExprKind::Unary(ast::UnOp::Neg, expr) => {
+                matches!(expr.kind, ast::ExprKind::Lit(_))
+            }
             // We can only resolve single-segment paths at the moment, because multi-segment paths
             // require type-checking: see `visit_generic_arg` in `src/librustc_resolve/late.rs`.
             ast::ExprKind::Path(None, path)

compiler/rustc_passes/src/dead.rs

@@ -23,18 +23,18 @@ use rustc_span::symbol::{sym, Symbol};
 // function, then we should explore its block to check for codes that
 // may need to be marked as live.
 fn should_explore(tcx: TyCtxt<'_>, hir_id: hir::HirId) -> bool {
-    match tcx.hir().find(hir_id) {
+    matches!(
+        tcx.hir().find(hir_id),
         Some(
             Node::Item(..)
-            | Node::ImplItem(..)
-            | Node::ForeignItem(..)
-            | Node::TraitItem(..)
-            | Node::Variant(..)
-            | Node::AnonConst(..)
-            | Node::Pat(..),
-        ) => true,
-        _ => false,
-    }
+                | Node::ImplItem(..)
+                | Node::ForeignItem(..)
+                | Node::TraitItem(..)
+                | Node::Variant(..)
+                | Node::AnonConst(..)
+                | Node::Pat(..),
+        )
+    )
 }
 
 struct MarkSymbolVisitor<'tcx> {
@@ -500,16 +500,16 @@ struct DeadVisitor<'tcx> {
 
 impl DeadVisitor<'tcx> {
     fn should_warn_about_item(&mut self, item: &hir::Item<'_>) -> bool {
-        let should_warn = match item.kind {
+        let should_warn = matches!(
+            item.kind,
             hir::ItemKind::Static(..)
-            | hir::ItemKind::Const(..)
-            | hir::ItemKind::Fn(..)
-            | hir::ItemKind::TyAlias(..)
-            | hir::ItemKind::Enum(..)
-            | hir::ItemKind::Struct(..)
-            | hir::ItemKind::Union(..) => true,
-            _ => false,
-        };
+                | hir::ItemKind::Const(..)
+                | hir::ItemKind::Fn(..)
+                | hir::ItemKind::TyAlias(..)
+                | hir::ItemKind::Enum(..)
+                | hir::ItemKind::Struct(..)
+                | hir::ItemKind::Union(..)
+        );
         should_warn && !self.symbol_is_live(item.hir_id)
     }
 

compiler/rustc_passes/src/liveness.rs

@@ -367,10 +367,7 @@ impl<'tcx> Visitor<'tcx> for IrMaps<'tcx> {
     }
 
     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
-        let is_shorthand = match param.pat.kind {
-            rustc_hir::PatKind::Struct(..) => true,
-            _ => false,
-        };
+        let is_shorthand = matches!(param.pat.kind, rustc_hir::PatKind::Struct(..));
         param.pat.each_binding(|_bm, hir_id, _x, ident| {
             let var = if is_shorthand {
                 Local(LocalInfo { id: hir_id, name: ident.name, is_shorthand: true })

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1653,17 +1653,14 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
         for missing in &self.missing_named_lifetime_spots {
             match missing {
                 MissingLifetimeSpot::Generics(generics) => {
-                    let (span, sugg) = if let Some(param) =
-                        generics.params.iter().find(|p| match p.kind {
-                            hir::GenericParamKind::Type {
-                                synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
-                                ..
-                            } => false,
-                            hir::GenericParamKind::Lifetime {
-                                kind: hir::LifetimeParamKind::Elided,
-                            } => false,
-                            _ => true,
-                        }) {
+                    let (span, sugg) = if let Some(param) = generics.params.iter().find(|p| {
+                        !matches!(p.kind, hir::GenericParamKind::Type {
+                            synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
+                            ..
+                        } | hir::GenericParamKind::Lifetime {
+                            kind: hir::LifetimeParamKind::Elided,
+                        })
+                    }) {
                         (param.span.shrink_to_lo(), format!("{}, ", lifetime_ref))
                     } else {
                         suggests_in_band = true;

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -35,10 +35,7 @@ pub enum AutoTraitResult<A> {
 #[allow(dead_code)]
 impl<A> AutoTraitResult<A> {
     fn is_auto(&self) -> bool {
-        match *self {
-            AutoTraitResult::PositiveImpl(_) | AutoTraitResult::NegativeImpl => true,
-            _ => false,
-        }
+        matches!(self, AutoTraitResult::PositiveImpl(_) | AutoTraitResult::NegativeImpl)
     }
 }
 
@@ -601,10 +598,7 @@ impl AutoTraitFinder<'tcx> {
     }
 
     fn is_self_referential_projection(&self, p: ty::PolyProjectionPredicate<'_>) -> bool {
-        match *p.ty().skip_binder().kind() {
-            ty::Projection(proj) if proj == p.skip_binder().projection_ty => true,
-            _ => false,
-        }
+        matches!(*p.ty().skip_binder().kind(), ty::Projection(proj) if proj == p.skip_binder().projection_ty)
     }
 
     fn evaluate_nested_obligations(

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -193,10 +193,8 @@ fn overlap_within_probe(
     let intercrate_ambiguity_causes = selcx.take_intercrate_ambiguity_causes();
     debug!("overlap: intercrate_ambiguity_causes={:#?}", intercrate_ambiguity_causes);
 
-    let involves_placeholder = match selcx.infcx().region_constraints_added_in_snapshot(snapshot) {
-        Some(true) => true,
-        _ => false,
-    };
+    let involves_placeholder =
+        matches!(selcx.infcx().region_constraints_added_in_snapshot(snapshot), Some(true));
 
     Some(OverlapResult { impl_header, intercrate_ambiguity_causes, involves_placeholder })
 }

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -861,10 +861,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
 
         let args_str = |arguments: &[ArgKind], other: &[ArgKind]| {
             let arg_length = arguments.len();
-            let distinct = match &other[..] {
-                &[ArgKind::Tuple(..)] => true,
-                _ => false,
-            };
+            let distinct = matches!(other, &[ArgKind::Tuple(..)]);
             match (arg_length, arguments.get(0)) {
                 (1, Some(&ArgKind::Tuple(_, ref fields))) => {
                     format!("a single {}-tuple as argument", fields.len())
@@ -1201,12 +1198,9 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
                     normalized_ty, data.ty
                 );
 
-                let is_normalized_ty_expected = match &obligation.cause.code {
-                    ObligationCauseCode::ItemObligation(_)
+                let is_normalized_ty_expected = !matches!(obligation.cause.code, ObligationCauseCode::ItemObligation(_)
                     | ObligationCauseCode::BindingObligation(_, _)
-                    | ObligationCauseCode::ObjectCastObligation(_) => false,
-                    _ => true,
-                };
+                    | ObligationCauseCode::ObjectCastObligation(_));
 
                 if let Err(error) = self.at(&obligation.cause, obligation.param_env).eq_exp(
                     is_normalized_ty_expected,

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -323,9 +323,8 @@ pub fn normalize_param_env_or_error<'tcx>(
     // This works fairly well because trait matching  does not actually care about param-env
     // TypeOutlives predicates - these are normally used by regionck.
     let outlives_predicates: Vec<_> = predicates
-        .drain_filter(|predicate| match predicate.skip_binders() {
-            ty::PredicateAtom::TypeOutlives(..) => true,
-            _ => false,
+        .drain_filter(|predicate| {
+            matches!(predicate.skip_binders(), ty::PredicateAtom::TypeOutlives(..))
         })
         .collect();
 

compiler/rustc_typeck/src/astconv/generics.rs

@@ -526,18 +526,16 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         generics: &ty::Generics,
     ) -> bool {
         let explicit = !seg.infer_args;
-        let impl_trait =
-            generics.params.iter().any(|param| match param.kind {
-                ty::GenericParamDefKind::Type {
-                    synthetic:
-                        Some(
-                            hir::SyntheticTyParamKind::ImplTrait
-                            | hir::SyntheticTyParamKind::FromAttr,
-                        ),
-                    ..
-                } => true,
-                _ => false,
-            });
+        let impl_trait = generics.params.iter().any(|param| {
+            matches!(param.kind, ty::GenericParamDefKind::Type {
+                synthetic:
+                    Some(
+                        hir::SyntheticTyParamKind::ImplTrait
+                        | hir::SyntheticTyParamKind::FromAttr,
+                    ),
+                ..
+            })
+        });
 
         if explicit && impl_trait {
             let spans = seg

compiler/rustc_typeck/src/check/check.rs

@@ -543,10 +543,9 @@ pub(super) fn check_opaque_for_inheriting_lifetimes(
 
         if let Some(ty) = prohibit_opaque.break_value() {
             let is_async = match item.kind {
-                ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => match origin {
-                    hir::OpaqueTyOrigin::AsyncFn => true,
-                    _ => false,
-                },
+                ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => {
+                    matches!(origin, hir::OpaqueTyOrigin::AsyncFn)
+                }
                 _ => unreachable!(),
             };
 
@@ -1321,10 +1320,7 @@ pub fn check_enum<'tcx>(
     }
 
     if tcx.adt_def(def_id).repr.int.is_none() && tcx.features().arbitrary_enum_discriminant {
-        let is_unit = |var: &hir::Variant<'_>| match var.data {
-            hir::VariantData::Unit(..) => true,
-            _ => false,
-        };
+        let is_unit = |var: &hir::Variant<'_>| matches!(var.data, hir::VariantData::Unit(..));
 
         let has_disr = |var: &hir::Variant<'_>| var.disr_expr.is_some();
         let has_non_units = vs.iter().any(|var| !is_unit(var));

compiler/rustc_typeck/src/check/fn_ctxt/checks.rs

@@ -325,10 +325,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     self.warn_if_unreachable(arg.hir_id, arg.span, "expression");
                 }
 
-                let is_closure = match arg.kind {
-                    ExprKind::Closure(..) => true,
-                    _ => false,
-                };
+                let is_closure = matches!(arg.kind, ExprKind::Closure(..));
 
                 if is_closure != check_closures {
                     continue;

compiler/rustc_typeck/src/check/regionck.rs

@@ -354,10 +354,7 @@ impl<'a, 'tcx> Visitor<'tcx> for RegionCtxt<'a, 'tcx> {
         hir_id: hir::HirId,
     ) {
         assert!(
-            match fk {
-                intravisit::FnKind::Closure(..) => true,
-                _ => false,
-            },
+            matches!(fk, intravisit::FnKind::Closure(..)),
             "visit_fn invoked for something other than a closure"
         );
 

compiler/rustc_typeck/src/collect.rs

@@ -156,10 +156,10 @@ crate fn placeholder_type_error(
         if let Some(span) = span {
             sugg.push((span, format!("<{}>", type_name)));
         }
-    } else if let Some(arg) = generics.iter().find(|arg| match arg.name {
-        hir::ParamName::Plain(Ident { name: kw::Underscore, .. }) => true,
-        _ => false,
-    }) {
+    } else if let Some(arg) = generics
+        .iter()
+        .find(|arg| matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. })))
+    {
         // Account for `_` already present in cases like `struct S<_>(_);` and suggest
         // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
         sugg.push((arg.span, (*type_name).to_string()));

compiler/rustc_typeck/src/expr_use_visitor.rs

@@ -595,10 +595,10 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         let upvars = self.tcx().upvars_mentioned(self.body_owner);
 
         // For purposes of this function, generator and closures are equivalent.
-        let body_owner_is_closure = match self.tcx().type_of(self.body_owner.to_def_id()).kind() {
-            ty::Closure(..) | ty::Generator(..) => true,
-            _ => false,
-        };
+        let body_owner_is_closure = matches!(
+            self.tcx().type_of(self.body_owner.to_def_id()).kind(),
+            ty::Closure(..) | ty::Generator(..)
+        );
 
         if let Some(min_captures) = self.mc.typeck_results.closure_min_captures.get(&closure_def_id)
         {