Auto merge of #78424 - jyn514:THE-PAPERCLIP-COMETH, r=davidtwco

Fix some more clippy warnings

Found while working on https://github.com/rust-lang/rust/pull/77351. It turns out that `x.py clippy --fix` does work on that branch as long as you pass `CARGOFLAGS=--lib`.

compiler/rustc_arena/src/lib.rs

@@ -228,7 +228,7 @@ impl<T> TypedArena<T> {
                 // bytes, then this chunk will be least double the previous
                 // chunk's size.
                 new_cap = last_chunk.storage.len().min(HUGE_PAGE / elem_size / 2);
-                new_cap = new_cap * 2;
+                new_cap *= 2;
             } else {
                 new_cap = PAGE / elem_size;
             }
@@ -346,7 +346,7 @@ impl DroplessArena {
                 // bytes, then this chunk will be least double the previous
                 // chunk's size.
                 new_cap = last_chunk.storage.len().min(HUGE_PAGE / 2);
-                new_cap = new_cap * 2;
+                new_cap *= 2;
             } else {
                 new_cap = PAGE;
             }
@@ -562,10 +562,8 @@ impl DropArena {
         // Record the destructors after doing the allocation as that may panic
         // and would cause `object`'s destructor to run twice if it was recorded before
         for i in 0..len {
-            destructors.push(DropType {
+            destructors
-                drop_fn: drop_for_type::<T>,
+                .push(DropType { drop_fn: drop_for_type::<T>, obj: start_ptr.add(i) as *mut u8 });
-                obj: start_ptr.offset(i as isize) as *mut u8,
-            });
         }
 
         slice::from_raw_parts_mut(start_ptr, len)

compiler/rustc_ast_lowering/src/lib.rs

@@ -490,10 +490,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         let count = generics
                             .params
                             .iter()
-                            .filter(|param| match param.kind {
+                            .filter(|param| matches!(param.kind, ast::GenericParamKind::Lifetime { .. }))
-                                ast::GenericParamKind::Lifetime { .. } => true,
-                                _ => false,
-                            })
                             .count();
                         self.lctx.type_def_lifetime_params.insert(def_id.to_def_id(), count);
                     }

compiler/rustc_ast_lowering/src/path.rs

@@ -262,10 +262,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             self.lower_angle_bracketed_parameter_data(&Default::default(), param_mode, itctx)
         };
 
-        let has_lifetimes = generic_args.args.iter().any(|arg| match arg {
+        let has_lifetimes =
-            GenericArg::Lifetime(_) => true,
+            generic_args.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_)));
-            _ => false,
-        });
         let first_generic_span = generic_args
             .args
             .iter()

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -639,15 +639,13 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
         if !self.is_beginning_of_line() {
             self.break_offset(n, off)
-        } else {
+        } else if off != 0 && self.last_token().is_hardbreak_tok() {
-            if off != 0 && self.last_token().is_hardbreak_tok() {
             // We do something pretty sketchy here: tuck the nonzero
             // offset-adjustment we were going to deposit along with the
             // break into the previous hardbreak.
             self.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
         }
     }
-    }
 
     fn nonterminal_to_string(&self, nt: &Nonterminal) -> String {
         match *nt {

compiler/rustc_attr/src/builtin.rs

@@ -901,8 +901,7 @@ pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                         )
                         .emit();
                     }
-                } else {
+                } else if let Some(meta_item) = item.meta_item() {
-                    if let Some(meta_item) = item.meta_item() {
                     if meta_item.has_name(sym::align) {
                         if let MetaItemKind::NameValue(ref value) = meta_item.kind {
                             recognised = true;
@@ -935,7 +934,6 @@ pub fn find_repr_attrs(sess: &Session, attr: &Attribute) -> Vec<ReprAttr> {
                         }
                     }
                 }
-                }
                 if !recognised {
                     // Not a word we recognize
                     struct_span_err!(

compiler/rustc_codegen_llvm/src/allocator.rs

@@ -93,7 +93,7 @@ pub(crate) unsafe fn codegen(
     let args = [usize, usize]; // size, align
 
     let ty = llvm::LLVMFunctionType(void, args.as_ptr(), args.len() as c_uint, False);
-    let name = format!("__rust_alloc_error_handler");
+    let name = "__rust_alloc_error_handler".to_string();
     let llfn = llvm::LLVMRustGetOrInsertFunction(llmod, name.as_ptr().cast(), name.len(), ty);
     // -> ! DIFlagNoReturn
     llvm::Attribute::NoReturn.apply_llfn(llvm::AttributePlace::Function, llfn);

compiler/rustc_codegen_llvm/src/asm.rs

@@ -302,14 +302,12 @@ impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
             } else if options.contains(InlineAsmOptions::READONLY) {
                 llvm::Attribute::ReadOnly.apply_callsite(llvm::AttributePlace::Function, result);
             }
-        } else {
+        } else if options.contains(InlineAsmOptions::NOMEM) {
-            if options.contains(InlineAsmOptions::NOMEM) {
             llvm::Attribute::InaccessibleMemOnly
                 .apply_callsite(llvm::AttributePlace::Function, result);
         } else {
             // LLVM doesn't have an attribute to represent ReadOnly + SideEffect
         }
-        }
 
         // Write results to outputs
         for (idx, op) in operands.iter().enumerate() {

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -900,7 +900,7 @@ impl ThinLTOKeysMap {
         let file = File::open(path)?;
         for line in io::BufReader::new(file).lines() {
             let line = line?;
-            let mut split = line.split(" ");
+            let mut split = line.split(' ');
             let module = split.next().unwrap();
             let key = split.next().unwrap();
             assert_eq!(split.next(), None, "Expected two space-separated values, found {:?}", line);

compiler/rustc_codegen_llvm/src/builder.rs

@@ -732,10 +732,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         let src_ty = self.cx.val_ty(val);
         let float_width = self.cx.float_width(src_ty);
         let int_width = self.cx.int_width(dest_ty);
-        match (int_width, float_width) {
+        matches!((int_width, float_width), (32, 32) | (32, 64) | (64, 32) | (64, 64))
-            (32, 32) | (32, 64) | (64, 32) | (64, 64) => true,
-            _ => false,
-        }
     }
 
     fn fptoui(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {

compiler/rustc_codegen_llvm/src/consts.rs

@@ -397,11 +397,9 @@ impl StaticMethods for CodegenCx<'ll, 'tcx> {
 
             // As an optimization, all shared statics which do not have interior
             // mutability are placed into read-only memory.
-            if !is_mutable {
+            if !is_mutable && self.type_is_freeze(ty) {
-                if self.type_is_freeze(ty) {
                 llvm::LLVMSetGlobalConstant(g, llvm::True);
             }
-            }
 
             debuginfo::create_global_var_metadata(&self, def_id, g);
 

compiler/rustc_codegen_llvm/src/context.rs

@@ -122,11 +122,11 @@ pub unsafe fn create_module(
     if llvm_util::get_major_version() < 9 {
         target_data_layout = strip_function_ptr_alignment(target_data_layout);
     }
-    if llvm_util::get_major_version() < 10 {
+    if llvm_util::get_major_version() < 10
-        if sess.target.arch == "x86" || sess.target.arch == "x86_64" {
+        && (sess.target.arch == "x86" || sess.target.arch == "x86_64")
+    {
         target_data_layout = strip_x86_address_spaces(target_data_layout);
     }
-    }
 
     // Ensure the data-layout values hardcoded remain the defaults.
     if sess.target.options.is_builtin {
@@ -864,7 +864,7 @@ impl<'b, 'tcx> CodegenCx<'b, 'tcx> {
         // user defined names
         let mut name = String::with_capacity(prefix.len() + 6);
         name.push_str(prefix);
-        name.push_str(".");
+        name.push('.');
         base_n::push_str(idx as u128, base_n::ALPHANUMERIC_ONLY, &mut name);
         name
     }

compiler/rustc_codegen_llvm/src/debuginfo/mod.rs

@@ -435,7 +435,7 @@ impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             name_to_append_suffix_to.push('<');
             for (i, actual_type) in substs.types().enumerate() {
                 if i != 0 {
-                    name_to_append_suffix_to.push_str(",");
+                    name_to_append_suffix_to.push(',');
                 }
 
                 let actual_type =

compiler/rustc_data_structures/src/graph/scc/mod.rs

@@ -307,10 +307,7 @@ where
     fn walk_unvisited_node(&mut self, depth: usize, node: G::Node) -> WalkReturn<S> {
         debug!("walk_unvisited_node(depth = {:?}, node = {:?})", depth, node);
 
-        debug_assert!(match self.node_states[node] {
+        debug_assert!(matches!(self.node_states[node], NodeState::NotVisited));
-            NodeState::NotVisited => true,
-            _ => false,
-        });
 
         // Push `node` onto the stack.
         self.node_states[node] = NodeState::BeingVisited { depth };

compiler/rustc_data_structures/src/sso/map.rs

@@ -395,7 +395,7 @@ where
     V: Copy,
 {
     fn extend<T: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: T) {
-        self.extend(iter.into_iter().map(|(k, v)| (k.clone(), v.clone())))
+        self.extend(iter.into_iter().map(|(k, v)| (*k, *v)))
     }
 
     #[inline]
@@ -451,7 +451,7 @@ impl<'a, K, V> IntoIterator for &'a SsoHashMap<K, V> {
     fn into_iter(self) -> Self::IntoIter {
         match self {
             SsoHashMap::Array(array) => EitherIter::Left(array.into_iter().map(adapt_array_ref_it)),
-            SsoHashMap::Map(map) => EitherIter::Right(map.into_iter()),
+            SsoHashMap::Map(map) => EitherIter::Right(map.iter()),
         }
     }
 }
@@ -469,7 +469,7 @@ impl<'a, K, V> IntoIterator for &'a mut SsoHashMap<K, V> {
     fn into_iter(self) -> Self::IntoIter {
         match self {
             SsoHashMap::Array(array) => EitherIter::Left(array.into_iter().map(adapt_array_mut_it)),
-            SsoHashMap::Map(map) => EitherIter::Right(map.into_iter()),
+            SsoHashMap::Map(map) => EitherIter::Right(map.iter_mut()),
         }
     }
 }

compiler/rustc_driver/src/lib.rs

@@ -716,7 +716,7 @@ impl RustcDefaultCalls {
                 TargetList => {
                     let mut targets =
                         rustc_target::spec::TARGETS.iter().copied().collect::<Vec<_>>();
-                    targets.sort();
+                    targets.sort_unstable();
                     println!("{}", targets.join("\n"));
                 }
                 Sysroot => println!("{}", sess.sysroot.display()),

compiler/rustc_errors/src/json.rs

@@ -136,10 +136,7 @@ impl Emitter for JsonEmitter {
     }
 
     fn should_show_explain(&self) -> bool {
-        match self.json_rendered {
+        !matches!(self.json_rendered, HumanReadableErrorType::Short(_))
-            HumanReadableErrorType::Short(_) => false,
-            _ => true,
-        }
     }
 }
 

compiler/rustc_errors/src/lib.rs

@@ -91,10 +91,7 @@ pub enum SuggestionStyle {
 
 impl SuggestionStyle {
     fn hide_inline(&self) -> bool {
-        match *self {
+        !matches!(*self, SuggestionStyle::ShowCode)
-            SuggestionStyle::ShowCode => false,
-            _ => true,
-        }
     }
 }
 
@@ -1038,10 +1035,7 @@ impl Level {
     }
 
     pub fn is_failure_note(&self) -> bool {
-        match *self {
+        matches!(*self, FailureNote)
-            FailureNote => true,
-            _ => false,
-        }
     }
 }
 

compiler/rustc_errors/src/snippet.rs

@@ -158,10 +158,7 @@ impl Annotation {
 
     pub fn takes_space(&self) -> bool {
         // Multiline annotations always have to keep vertical space.
-        match self.annotation_type {
+        matches!(self.annotation_type, AnnotationType::MultilineStart(_) | AnnotationType::MultilineEnd(_))
-            AnnotationType::MultilineStart(_) | AnnotationType::MultilineEnd(_) => true,
-            _ => false,
-        }
     }
 }
 

compiler/rustc_expand/src/mbe.rs

@@ -102,10 +102,7 @@ impl TokenTree {
 
     /// Returns `true` if the given token tree is delimited.
     fn is_delimited(&self) -> bool {
-        match *self {
+        matches!(*self, TokenTree::Delimited(..))
-            TokenTree::Delimited(..) => true,
-            _ => false,
-        }
     }
 
     /// Returns `true` if the given token tree is a token of the given kind.

compiler/rustc_expand/src/mbe/macro_check.rs

@@ -134,10 +134,7 @@ enum Stack<'a, T> {
 impl<'a, T> Stack<'a, T> {
     /// Returns whether a stack is empty.
     fn is_empty(&self) -> bool {
-        match *self {
+        matches!(*self, Stack::Empty)
-            Stack::Empty => true,
-            _ => false,
-        }
     }
 
     /// Returns a new stack with an element of top.

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -1036,17 +1036,16 @@ fn token_can_be_followed_by_any(tok: &mbe::TokenTree) -> bool {
 /// a fragment specifier (indeed, these fragments can be followed by
 /// ANYTHING without fear of future compatibility hazards).
 fn frag_can_be_followed_by_any(kind: NonterminalKind) -> bool {
-    match kind {
+    matches!(
+        kind,
         NonterminalKind::Item           // always terminated by `}` or `;`
         | NonterminalKind::Block        // exactly one token tree
         | NonterminalKind::Ident        // exactly one token tree
         | NonterminalKind::Literal      // exactly one token tree
         | NonterminalKind::Meta         // exactly one token tree
         | NonterminalKind::Lifetime     // exactly one token tree
-        | NonterminalKind::TT => true,  // exactly one token tree
+        | NonterminalKind::TT // exactly one token tree
-
+    )
-        _ => false,
-    }
 }
 
 enum IsInFollow {

compiler/rustc_expand/src/placeholders.rs

@@ -345,10 +345,10 @@ impl<'a, 'b> MutVisitor for PlaceholderExpander<'a, 'b> {
 
     fn visit_mod(&mut self, module: &mut ast::Mod) {
         noop_visit_mod(module, self);
-        module.items.retain(|item| match item.kind {
+        // remove macro definitions
-            ast::ItemKind::MacCall(_) if !self.cx.ecfg.keep_macs => false, // remove macro definitions
+        module.items.retain(
-            _ => true,
+            |item| !matches!(item.kind, ast::ItemKind::MacCall(_) if !self.cx.ecfg.keep_macs),
-        });
+        );
     }
 
     fn visit_mac(&mut self, _mac: &mut ast::MacCall) {

compiler/rustc_feature/src/builtin_attrs.rs

@@ -83,10 +83,7 @@ impl std::fmt::Debug for AttributeGate {
 
 impl AttributeGate {
     fn is_deprecated(&self) -> bool {
-        match *self {
+        matches!(*self, Self::Gated(Stability::Deprecated(_, _), ..))
-            Self::Gated(Stability::Deprecated(_, _), ..) => true,
-            _ => false,
-        }
     }
 }
 

compiler/rustc_hir/src/hir.rs

@@ -272,10 +272,7 @@ impl GenericArg<'_> {
     }
 
     pub fn is_const(&self) -> bool {
-        match self {
+        matches!(self, GenericArg::Const(_))
-            GenericArg::Const(_) => true,
-            _ => false,
-        }
     }
 
     pub fn descr(&self) -> &'static str {
@@ -980,17 +977,11 @@ impl BinOpKind {
     }
 
     pub fn is_lazy(self) -> bool {
-        match self {
+        matches!(self, BinOpKind::And | BinOpKind::Or)
-            BinOpKind::And | BinOpKind::Or => true,
-            _ => false,
-        }
     }
 
     pub fn is_shift(self) -> bool {
-        match self {
+        matches!(self, BinOpKind::Shl | BinOpKind::Shr)
-            BinOpKind::Shl | BinOpKind::Shr => true,
-            _ => false,
-        }
     }
 
     pub fn is_comparison(self) -> bool {
@@ -1070,10 +1061,7 @@ impl UnOp {
 
     /// Returns `true` if the unary operator takes its argument by value.
     pub fn is_by_value(self) -> bool {
-        match self {
+        matches!(self, Self::UnNeg | Self::UnNot)
-            Self::UnNeg | Self::UnNot => true,
-            _ => false,
-        }
     }
 }
 
@@ -1409,10 +1397,9 @@ impl Expr<'_> {
     /// on the given expression should be considered a place expression.
     pub fn is_place_expr(&self, mut allow_projections_from: impl FnMut(&Self) -> bool) -> bool {
         match self.kind {
-            ExprKind::Path(QPath::Resolved(_, ref path)) => match path.res {
+            ExprKind::Path(QPath::Resolved(_, ref path)) => {
-                Res::Local(..) | Res::Def(DefKind::Static, _) | Res::Err => true,
+                matches!(path.res, Res::Local(..) | Res::Def(DefKind::Static, _) | Res::Err)
-                _ => false,
+            }
-            },
 
             // Type ascription inherits its place expression kind from its
             // operand. See:
@@ -2204,10 +2191,7 @@ pub enum ImplicitSelfKind {
 impl ImplicitSelfKind {
     /// Does this represent an implicit self?
     pub fn has_implicit_self(&self) -> bool {
-        match *self {
+        !matches!(*self, ImplicitSelfKind::None)
-            ImplicitSelfKind::None => false,
-            _ => true,
-        }
     }
 }
 
@@ -2237,10 +2221,7 @@ impl Defaultness {
     }
 
     pub fn is_default(&self) -> bool {
-        match *self {
+        matches!(*self, Defaultness::Default { .. })
-            Defaultness::Default { .. } => true,
-            _ => false,
-        }
     }
 }
 
@@ -2371,10 +2352,7 @@ pub enum VisibilityKind<'hir> {
 
 impl VisibilityKind<'_> {
     pub fn is_pub(&self) -> bool {
-        match *self {
+        matches!(*self, VisibilityKind::Public)
-            VisibilityKind::Public => true,
-            _ => false,
-        }
     }
 
     pub fn is_pub_restricted(&self) -> bool {
@@ -2502,10 +2480,7 @@ pub struct FnHeader {
 
 impl FnHeader {
     pub fn is_const(&self) -> bool {
-        match &self.constness {
+        matches!(&self.constness, Constness::Const)
-            Constness::Const => true,
-            _ => false,
-        }
     }
 }
 

compiler/rustc_hir/src/pat_util.rs

@@ -92,10 +92,7 @@ impl hir::Pat<'_> {
     /// Checks if the pattern contains any patterns that bind something to
     /// an ident, e.g., `foo`, or `Foo(foo)` or `foo @ Bar(..)`.
     pub fn contains_bindings(&self) -> bool {
-        self.satisfies(|p| match p.kind {
+        self.satisfies(|p| matches!(p.kind, PatKind::Binding(..)))
-            PatKind::Binding(..) => true,
-            _ => false,
-        })
     }
 
     /// Checks if the pattern satisfies the given predicate on some sub-pattern.

compiler/rustc_hir_pretty/src/lib.rs

@@ -299,15 +299,13 @@ impl<'a> State<'a> {
     pub fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
         if !self.s.is_beginning_of_line() {
             self.s.break_offset(n, off)
-        } else {
+        } else if off != 0 && self.s.last_token().is_hardbreak_tok() {
-            if off != 0 && self.s.last_token().is_hardbreak_tok() {
             // We do something pretty sketchy here: tuck the nonzero
             // offset-adjustment we were going to deposit along with the
             // break into the previous hardbreak.
             self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
         }
     }
-    }
 
     // Synthesizes a comment that was not textually present in the original source
     // file.
@@ -1921,10 +1919,7 @@ impl<'a> State<'a> {
                 self.pclose();
             }
             PatKind::Box(ref inner) => {
-                let is_range_inner = match inner.kind {
+                let is_range_inner = matches!(inner.kind, PatKind::Range(..));
-                    PatKind::Range(..) => true,
-                    _ => false,
-                };
                 self.s.word("box ");
                 if is_range_inner {
                     self.popen();
@@ -1935,10 +1930,7 @@ impl<'a> State<'a> {
                 }
             }
             PatKind::Ref(ref inner, mutbl) => {
-                let is_range_inner = match inner.kind {
+                let is_range_inner = matches!(inner.kind, PatKind::Range(..));
-                    PatKind::Range(..) => true,
-                    _ => false,
-                };
                 self.s.word("&");
                 self.s.word(mutbl.prefix_str());
                 if is_range_inner {
@@ -2435,10 +2427,7 @@ impl<'a> State<'a> {
 //
 // Duplicated from `parse::classify`, but adapted for the HIR.
 fn expr_requires_semi_to_be_stmt(e: &hir::Expr<'_>) -> bool {
-    match e.kind {
+    !matches!(e.kind, hir::ExprKind::Match(..) | hir::ExprKind::Block(..) | hir::ExprKind::Loop(..))
-        hir::ExprKind::Match(..) | hir::ExprKind::Block(..) | hir::ExprKind::Loop(..) => false,
-        _ => true,
-    }
 }
 
 /// This statement requires a semicolon after it.

compiler/rustc_lexer/src/lib.rs

@@ -238,9 +238,10 @@ pub fn is_whitespace(c: char) -> bool {
     // Note that this set is stable (ie, it doesn't change with different
     // Unicode versions), so it's ok to just hard-code the values.
 
-    match c {
+    matches!(
+        c,
         // Usual ASCII suspects
-        | '\u{0009}' // \t
+        '\u{0009}'   // \t
         | '\u{000A}' // \n
         | '\u{000B}' // vertical tab
         | '\u{000C}' // form feed
@@ -257,9 +258,7 @@ pub fn is_whitespace(c: char) -> bool {
         // Dedicated whitespace characters from Unicode
         | '\u{2028}' // LINE SEPARATOR
         | '\u{2029}' // PARAGRAPH SEPARATOR
-        => true,
+    )
-        _ => false,
-    }
 }
 
 /// True if `c` is valid as a first character of an identifier.

compiler/rustc_lint/src/builtin.rs

@@ -1369,10 +1369,9 @@ impl TypeAliasBounds {
             hir::QPath::TypeRelative(ref ty, _) => {
                 // If this is a type variable, we found a `T::Assoc`.
                 match ty.kind {
-                    hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => match path.res {
+                    hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
-                        Res::Def(DefKind::TyParam, _) => true,
+                        matches!(path.res, Res::Def(DefKind::TyParam, _))
-                        _ => false,
+                    }
-                    },
                     _ => false,
                 }
             }
@@ -2381,12 +2380,11 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
                         return Some(InitKind::Zeroed);
                     } else if cx.tcx.is_diagnostic_item(sym::mem_uninitialized, def_id) {
                         return Some(InitKind::Uninit);
-                    } else if cx.tcx.is_diagnostic_item(sym::transmute, def_id) {
+                    } else if cx.tcx.is_diagnostic_item(sym::transmute, def_id) && is_zero(&args[0])
-                        if is_zero(&args[0]) {
+                    {
                         return Some(InitKind::Zeroed);
                     }
                 }
-                }
             } else if let hir::ExprKind::MethodCall(_, _, ref args, _) = expr.kind {
                 // Find problematic calls to `MaybeUninit::assume_init`.
                 let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id)?;
@@ -2880,7 +2878,7 @@ impl<'tcx> LateLintPass<'tcx> for ClashingExternDeclarations {
     fn check_foreign_item(&mut self, cx: &LateContext<'tcx>, this_fi: &hir::ForeignItem<'_>) {
         trace!("ClashingExternDeclarations: check_foreign_item: {:?}", this_fi);
         if let ForeignItemKind::Fn(..) = this_fi.kind {
-            let tcx = *&cx.tcx;
+            let tcx = cx.tcx;
             if let Some(existing_hid) = self.insert(tcx, this_fi) {
                 let existing_decl_ty = tcx.type_of(tcx.hir().local_def_id(existing_hid));
                 let this_decl_ty = tcx.type_of(tcx.hir().local_def_id(this_fi.hir_id));

compiler/rustc_lint/src/nonstandard_style.rs

@@ -320,7 +320,7 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
                                             .with_hi(lit.span.hi() - BytePos(right as u32)),
                                     )
                                 })
-                                .unwrap_or_else(|| lit.span);
+                                .unwrap_or(lit.span);
 
                             Some(Ident::new(name, sp))
                         } else {

compiler/rustc_lint/src/types.rs

@@ -544,15 +544,15 @@ impl<'tcx> LateLintPass<'tcx> for TypeLimits {
         }
 
         fn is_comparison(binop: hir::BinOp) -> bool {
-            match binop.node {
+            matches!(
+                binop.node,
                 hir::BinOpKind::Eq
                     | hir::BinOpKind::Lt
                     | hir::BinOpKind::Le
                     | hir::BinOpKind::Ne
                     | hir::BinOpKind::Ge
-                | hir::BinOpKind::Gt => true,
+                    | hir::BinOpKind::Gt
-                _ => false,
+            )
-            }
         }
     }
 }
@@ -1233,15 +1233,10 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
     }
 
     fn is_internal_abi(&self, abi: SpecAbi) -> bool {
-        if let SpecAbi::Rust
+        matches!(
-        | SpecAbi::RustCall
+            abi,
-        | SpecAbi::RustIntrinsic
+            SpecAbi::Rust | SpecAbi::RustCall | SpecAbi::RustIntrinsic | SpecAbi::PlatformIntrinsic
-        | SpecAbi::PlatformIntrinsic = abi
+        )
-        {
-            true
-        } else {
-            false
-        }
     }
 }
 

compiler/rustc_lint/src/unused.rs

@@ -752,14 +752,11 @@ impl UnusedDelimLint for UnusedParens {
                     && value.attrs.is_empty()
                     && !value.span.from_expansion()
                     && (ctx != UnusedDelimsCtx::LetScrutineeExpr
-                        || match inner.kind {
+                        || !matches!(inner.kind, ast::ExprKind::Binary(
-                            ast::ExprKind::Binary(
                                 rustc_span::source_map::Spanned { node, .. },
                                 _,
                                 _,
-                            ) if node.lazy() => false,
+                            ) if node.lazy()))
-                            _ => true,
-                        })
                 {
                     self.emit_unused_delims_expr(cx, value, ctx, left_pos, right_pos)
                 }

compiler/rustc_metadata/src/creader.rs

@@ -752,10 +752,7 @@ impl<'a> CrateLoader<'a> {
         // At this point we've determined that we need an allocator. Let's see
         // if our compilation session actually needs an allocator based on what
         // we're emitting.
-        let all_rlib = self.sess.crate_types().iter().all(|ct| match *ct {
+        let all_rlib = self.sess.crate_types().iter().all(|ct| matches!(*ct, CrateType::Rlib));
-            CrateType::Rlib => true,
-            _ => false,
-        });
         if all_rlib {
             return;
         }

compiler/rustc_metadata/src/locator.rs

@@ -633,12 +633,10 @@ impl<'a> CrateLocator<'a> {
             }
         }
 
-        if self.exact_paths.is_empty() {
+        if self.exact_paths.is_empty() && self.crate_name != root.name() {
-            if self.crate_name != root.name() {
             info!("Rejecting via crate name");
             return None;
         }
-        }
 
         if root.triple() != &self.triple {
             info!("Rejecting via crate triple: expected {} got {}", self.triple, root.triple());

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -220,10 +220,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     missing_lang_items => { cdata.get_missing_lang_items(tcx) }
 
     missing_extern_crate_item => {
-        let r = match *cdata.extern_crate.borrow() {
+        let r = matches!(*cdata.extern_crate.borrow(), Some(extern_crate) if !extern_crate.is_direct());
-            Some(extern_crate) if !extern_crate.is_direct() => true,
-            _ => false,
-        };
         r
     }
 
@@ -254,9 +251,11 @@ pub fn provide(providers: &mut Providers) {
             }
             _ => false,
         },
-        is_statically_included_foreign_item: |tcx, id| match tcx.native_library_kind(id) {
+        is_statically_included_foreign_item: |tcx, id| {
-            Some(NativeLibKind::StaticBundle | NativeLibKind::StaticNoBundle) => true,
+            matches!(
-            _ => false,
+                tcx.native_library_kind(id),
+                Some(NativeLibKind::StaticBundle | NativeLibKind::StaticNoBundle)
+            )
         },
         native_library_kind: |tcx, id| {
             tcx.native_libraries(id.krate)

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

@@ -262,10 +262,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             | ExprKind::ThreadLocalRef(_)
             | ExprKind::Call { .. } => {
                 // these are not places, so we need to make a temporary.
-                debug_assert!(match Category::of(&expr.kind) {
+                debug_assert!(!matches!(Category::of(&expr.kind), Some(Category::Place)));
-                    Some(Category::Place) => false,
-                    _ => true,
-                });
                 let temp =
                     unpack!(block = this.as_temp(block, expr.temp_lifetime, expr, mutability));
                 block.and(PlaceBuilder::from(temp))

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

@@ -260,10 +260,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             | ExprKind::ValueTypeAscription { .. } => {
                 // these do not have corresponding `Rvalue` variants,
                 // so make an operand and then return that
-                debug_assert!(match Category::of(&expr.kind) {
+                debug_assert!(!matches!(Category::of(&expr.kind), Some(Category::Rvalue(RvalueFunc::AsRvalue))));
-                    Some(Category::Rvalue(RvalueFunc::AsRvalue)) => false,
-                    _ => true,
-                });
                 let operand = unpack!(block = this.as_operand(block, scope, expr));
                 block.and(Rvalue::Use(operand))
             }

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

@@ -58,10 +58,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             }
             ExprKind::NeverToAny { source } => {
                 let source = this.hir.mirror(source);
-                let is_call = match source.kind {
+                let is_call = matches!(source.kind, ExprKind::Call { .. } | ExprKind::InlineAsm { .. });
-                    ExprKind::Call { .. } | ExprKind::InlineAsm { .. } => true,
-                    _ => false,
-                };
 
                 // (#66975) Source could be a const of type `!`, so has to
                 // exist in the generated MIR.

compiler/rustc_mir_build/src/build/matches/test.rs

@@ -250,8 +250,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         place,
                         ty,
                     );
-                } else {
+                } else if let [success, fail] = *make_target_blocks(self) {
-                    if let [success, fail] = *make_target_blocks(self) {
                     assert_eq!(value.ty, ty);
                     let expect = self.literal_operand(test.span, value);
                     let val = Operand::Copy(place);
@@ -260,7 +259,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     bug!("`TestKind::Eq` should have two target blocks");
                 }
             }
-            }
 
             TestKind::Range(PatRange { ref lo, ref hi, ref end }) => {
                 let lower_bound_success = self.cfg.start_new_block();

compiler/rustc_mir_build/src/build/scope.rs

@@ -331,8 +331,7 @@ impl DropTree {
             }
             if let DropKind::Value = drop_data.0.kind {
                 needs_block[drop_data.1] = Block::Own;
-            } else {
+            } else if drop_idx != ROOT_NODE {
-                if drop_idx != ROOT_NODE {
                 match &mut needs_block[drop_data.1] {
                     pred @ Block::None => *pred = Block::Shares(drop_idx),
                     pred @ Block::Shares(_) => *pred = Block::Own,
@@ -340,7 +339,6 @@ impl DropTree {
                 }
             }
         }
-        }
 
         debug!("assign_blocks: blocks = {:#?}", blocks);
         assert!(entry_points.is_empty());
@@ -461,9 +459,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let breakable_scope = self.scopes.breakable_scopes.pop().unwrap();
         assert!(breakable_scope.region_scope == region_scope);
         let break_block = self.build_exit_tree(breakable_scope.break_drops, None);
-        breakable_scope.continue_drops.map(|drops| {
+        if let Some(drops) = breakable_scope.continue_drops { self.build_exit_tree(drops, loop_block); }
-            self.build_exit_tree(drops, loop_block);
-        });
         match (normal_exit_block, break_block) {
             (Some(block), None) | (None, Some(block)) => block,
             (None, None) => self.cfg.start_new_block().unit(),

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -316,8 +316,7 @@ fn make_mirror_unadjusted<'a, 'tcx>(
         hir::ExprKind::Unary(hir::UnOp::UnNeg, ref arg) => {
             if cx.typeck_results().is_method_call(expr) {
                 overloaded_operator(cx, expr, vec![arg.to_ref()])
-            } else {
+            } else if let hir::ExprKind::Lit(ref lit) = arg.kind {
-                if let hir::ExprKind::Lit(ref lit) = arg.kind {
                 ExprKind::Literal {
                     literal: cx.const_eval_literal(&lit.node, expr_ty, lit.span, true),
                     user_ty: None,
@@ -327,7 +326,6 @@ fn make_mirror_unadjusted<'a, 'tcx>(
                 ExprKind::Unary { op: UnOp::Neg, arg: arg.to_ref() }
             }
         }
-        }
 
         hir::ExprKind::Struct(ref qpath, ref fields, ref base) => match expr_ty.kind() {
             ty::Adt(adt, substs) => match adt.adt_kind() {

compiler/rustc_mir_build/src/thir/pattern/_match.rs

@@ -337,10 +337,7 @@ impl<'tcx> PatternFolder<'tcx> for LiteralExpander {
 
 impl<'tcx> Pat<'tcx> {
     pub(super) fn is_wildcard(&self) -> bool {
-        match *self.kind {
+        matches!(*self.kind, PatKind::Binding { subpattern: None, .. } | PatKind::Wild)
-            PatKind::Binding { subpattern: None, .. } | PatKind::Wild => true,
-            _ => false,
-        }
     }
 }
 
@@ -1358,10 +1355,7 @@ impl<'tcx> Usefulness<'tcx> {
     }
 
     fn is_useful(&self) -> bool {
-        match *self {
+        !matches!(*self, NotUseful)
-            NotUseful => false,
-            _ => true,
-        }
     }
 
     fn apply_constructor<'p>(
@@ -1623,10 +1617,7 @@ struct IntRange<'tcx> {
 impl<'tcx> IntRange<'tcx> {
     #[inline]
     fn is_integral(ty: Ty<'_>) -> bool {
-        match ty.kind() {
+        matches!(ty.kind(), ty::Char | ty::Int(_) | ty::Uint(_) | ty::Bool)
-            ty::Char | ty::Int(_) | ty::Uint(_) | ty::Bool => true,
-            _ => false,
-        }
     }
 
     fn is_singleton(&self) -> bool {

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -223,10 +223,7 @@ impl<'tcx> fmt::Display for Pat<'tcx> {
                     BindingMode::ByValue => mutability == Mutability::Mut,
                     BindingMode::ByRef(bk) => {
                         write!(f, "ref ")?;
-                        match bk {
+                        matches!(bk, BorrowKind::Mut { .. })
-                            BorrowKind::Mut { .. } => true,
-                            _ => false,
-                        }
                     }
                 };
                 if is_mut {

compiler/rustc_parse/src/lib.rs

@@ -606,7 +606,7 @@ fn prepend_attrs(
 ) -> Option<tokenstream::TokenStream> {
     let tokens = tokens?.clone().into_token_stream();
     if attrs.is_empty() {
-        return Some(tokens.clone());
+        return Some(tokens);
     }
     let mut builder = tokenstream::TokenStreamBuilder::new();
     for attr in attrs {
@@ -622,6 +622,6 @@ fn prepend_attrs(
                 .into_token_stream(),
         );
     }
-    builder.push(tokens.clone());
+    builder.push(tokens);
     Some(builder.build())
 }

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1359,11 +1359,7 @@ impl<'a> Parser<'a> {
         (self.token == token::Lt && // `foo:<bar`, likely a typoed turbofish.
             self.look_ahead(1, |t| t.is_ident() && !t.is_reserved_ident()))
             || self.token.is_ident() &&
-            match node {
+            matches!(node, ast::ExprKind::Path(..) | ast::ExprKind::Field(..)) &&
-                // `foo::` → `foo:` or `foo.bar::` → `foo.bar:`
-                ast::ExprKind::Path(..) | ast::ExprKind::Field(..) => true,
-                _ => false,
-            } &&
             !self.token.is_reserved_ident() &&           // v `foo:bar(baz)`
             self.look_ahead(1, |t| t == &token::OpenDelim(token::Paren))
             || self.look_ahead(1, |t| t == &token::OpenDelim(token::Brace)) // `foo:bar {`

compiler/rustc_parse/src/parser/item.rs

@@ -376,8 +376,7 @@ impl<'a> Parser<'a> {
                     format!(" {} ", kw),
                     Applicability::MachineApplicable,
                 );
-            } else {
+            } else if let Ok(snippet) = self.span_to_snippet(ident_sp) {
-                if let Ok(snippet) = self.span_to_snippet(ident_sp) {
                 err.span_suggestion(
                     full_sp,
                     "if you meant to call a macro, try",
@@ -391,7 +390,6 @@ impl<'a> Parser<'a> {
                               and add a trailing `!` after the identifier",
                 );
             }
-            }
             Err(err)
         } else if self.look_ahead(1, |t| *t == token::Lt) {
             let ident = self.parse_ident().unwrap();
@@ -982,10 +980,7 @@ impl<'a> Parser<'a> {
                 if token.is_keyword(kw::Move) {
                     return true;
                 }
-                match token.kind {
+                matches!(token.kind, token::BinOp(token::Or) | token::OrOr)
-                    token::BinOp(token::Or) | token::OrOr => true,
-                    _ => false,
-                }
             })
         } else {
             false

compiler/rustc_parse/src/parser/nonterminal.rs

@@ -38,16 +38,13 @@ impl<'a> Parser<'a> {
             },
             NonterminalKind::Block => match token.kind {
                 token::OpenDelim(token::Brace) => true,
-                token::Interpolated(ref nt) => match **nt {
+                token::Interpolated(ref nt) => !matches!(**nt, token::NtItem(_)
-                    token::NtItem(_)
                     | token::NtPat(_)
                     | token::NtTy(_)
                     | token::NtIdent(..)
                     | token::NtMeta(_)
                     | token::NtPath(_)
-                    | token::NtVis(_) => false, // none of these may start with '{'.
+                    | token::NtVis(_)),
-                    _ => true,
-                },
                 _ => false,
             },
             NonterminalKind::Path | NonterminalKind::Meta => match token.kind {
@@ -76,17 +73,14 @@ impl<'a> Parser<'a> {
             },
             NonterminalKind::Lifetime => match token.kind {
                 token::Lifetime(_) => true,
-                token::Interpolated(ref nt) => match **nt {
+                token::Interpolated(ref nt) => {
-                    token::NtLifetime(_) | token::NtTT(_) => true,
+                    matches!(**nt, token::NtLifetime(_) | token::NtTT(_))
+                }
                 _ => false,
             },
-                _ => false,
+            NonterminalKind::TT | NonterminalKind::Item | NonterminalKind::Stmt => {
-            },
+                !matches!(token.kind, token::CloseDelim(_))
-            NonterminalKind::TT | NonterminalKind::Item | NonterminalKind::Stmt => match token.kind
+            }
-            {
-                token::CloseDelim(_) => false,
-                _ => true,
-            },
         }
     }
 

compiler/rustc_parse/src/parser/pat.rs

@@ -149,7 +149,9 @@ impl<'a> Parser<'a> {
     /// Note that there are more tokens such as `@` for which we know that the `|`
     /// is an illegal parse. However, the user's intent is less clear in that case.
     fn recover_trailing_vert(&mut self, lo: Option<Span>) -> bool {
-        let is_end_ahead = self.look_ahead(1, |token| match &token.uninterpolate().kind {
+        let is_end_ahead = self.look_ahead(1, |token| {
+            matches!(
+                &token.uninterpolate().kind,
                 token::FatArrow // e.g. `a | => 0,`.
             | token::Ident(kw::If, false) // e.g. `a | if expr`.
             | token::Eq // e.g. `let a | = 0`.
@@ -158,8 +160,8 @@ impl<'a> Parser<'a> {
             | token::Comma // e.g. `let (a |,)`.
             | token::CloseDelim(token::Bracket) // e.g. `let [a | ]`.
             | token::CloseDelim(token::Paren) // e.g. `let (a | )`.
-            | token::CloseDelim(token::Brace) => true, // e.g. `let A { f: a | }`.
+            | token::CloseDelim(token::Brace) // e.g. `let A { f: a | }`.
-            _ => false,
+            )
         });
         match (is_end_ahead, &self.token.kind) {
             (true, token::BinOp(token::Or) | token::OrOr) => {
@@ -766,14 +768,12 @@ impl<'a> Parser<'a> {
         && !self.token.is_path_segment_keyword() // Avoid e.g. `Self` as it is a path.
         // Avoid `in`. Due to recovery in the list parser this messes with `for ( $pat in $expr )`.
         && !self.token.is_keyword(kw::In)
-        && self.look_ahead(1, |t| match t.kind { // Try to do something more complex?
+        // Try to do something more complex?
-            token::OpenDelim(token::Paren) // A tuple struct pattern.
+        && self.look_ahead(1, |t| !matches!(t.kind, token::OpenDelim(token::Paren) // A tuple struct pattern.
             | token::OpenDelim(token::Brace) // A struct pattern.
             | token::DotDotDot | token::DotDotEq | token::DotDot // A range pattern.
             | token::ModSep // A tuple / struct variant pattern.
-            | token::Not => false, // A macro expanding to a pattern.
+            | token::Not)) // A macro expanding to a pattern.
-            _ => true,
-        })
     }
 
     /// Parses `ident` or `ident @ pat`.

compiler/rustc_parse/src/parser/path.rs

@@ -187,12 +187,14 @@ impl<'a> Parser<'a> {
     pub(super) fn parse_path_segment(&mut self, style: PathStyle) -> PResult<'a, PathSegment> {
         let ident = self.parse_path_segment_ident()?;
 
-        let is_args_start = |token: &Token| match token.kind {
+        let is_args_start = |token: &Token| {
+            matches!(
+                token.kind,
                 token::Lt
                     | token::BinOp(token::Shl)
                     | token::OpenDelim(token::Paren)
-            | token::LArrow => true,
+                    | token::LArrow
-            _ => false,
+            )
         };
         let check_args_start = |this: &mut Self| {
             this.expected_tokens.extend_from_slice(&[

compiler/rustc_privacy/src/lib.rs

@@ -1219,9 +1219,11 @@ impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
                 .maybe_typeck_results
                 .and_then(|typeck_results| typeck_results.type_dependent_def(id)),
         };
-        let def = def.filter(|(kind, _)| match kind {
+        let def = def.filter(|(kind, _)| {
-            DefKind::AssocFn | DefKind::AssocConst | DefKind::AssocTy | DefKind::Static => true,
+            matches!(
-            _ => false,
+                kind,
+                DefKind::AssocFn | DefKind::AssocConst | DefKind::AssocTy | DefKind::Static
+            )
         });
         if let Some((kind, def_id)) = def {
             let is_local_static =

compiler/rustc_query_system/src/dep_graph/graph.rs

@@ -292,11 +292,9 @@ impl<K: DepKind> DepGraph<K> {
                 );
 
                 data.colors.insert(prev_index, color);
-            } else {
+            } else if print_status {
-                if print_status {
                 eprintln!("[task::new] {:?}", key);
             }
-            }
 
             (result, dep_node_index)
         } else {

compiler/rustc_query_system/src/query/plumbing.rs

@@ -612,11 +612,9 @@ where
 
     prof_timer.finish_with_query_invocation_id(dep_node_index.into());
 
-    if unlikely!(!diagnostics.is_empty()) {
+    if unlikely!(!diagnostics.is_empty()) && dep_node.kind != DepKind::NULL {
-        if dep_node.kind != DepKind::NULL {
         tcx.store_diagnostics(dep_node_index, diagnostics);
     }
-    }
 
     let result = job.complete(result, dep_node_index);
 

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -344,10 +344,10 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 
     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
         // If any statements are items, we need to create an anonymous module
-        block.stmts.iter().any(|statement| match statement.kind {
+        block
-            StmtKind::Item(_) | StmtKind::MacCall(_) => true,
+            .stmts
-            _ => false,
+            .iter()
-        })
+            .any(|statement| matches!(statement.kind, StmtKind::Item(_) | StmtKind::MacCall(_)))
     }
 
     // Add an import to the current module.

compiler/rustc_resolve/src/diagnostics.rs

@@ -922,15 +922,10 @@ impl<'a> Resolver<'a> {
         );
         self.add_typo_suggestion(err, suggestion, ident.span);
 
-        let import_suggestions = self.lookup_import_candidates(
+        let import_suggestions =
-            ident,
+            self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, |res| {
-            Namespace::MacroNS,
+                matches!(res, Res::Def(DefKind::Macro(MacroKind::Bang), _))
-            parent_scope,
+            });
-            |res| match res {
-                Res::Def(DefKind::Macro(MacroKind::Bang), _) => true,
-                _ => false,
-            },
-        );
         show_candidates(err, None, &import_suggestions, false, true);
 
         if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
@@ -1010,11 +1005,9 @@ impl<'a> Resolver<'a> {
     fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
         let res = b.res();
         if b.span.is_dummy() {
-            let add_built_in = match b.res() {
             // These already contain the "built-in" prefix or look bad with it.
-                Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
+            let add_built_in =
-                _ => true,
+                !matches!(b.res(), Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod);
-            };
             let (built_in, from) = if from_prelude {
                 ("", " from prelude")
             } else if b.is_extern_crate()
@@ -1610,10 +1603,7 @@ fn find_span_immediately_after_crate_name(
         if *c == ':' {
             num_colons += 1;
         }
-        match c {
+        !matches!(c, ':' if num_colons == 2)
-            ':' if num_colons == 2 => false,
-            _ => true,
-        }
     });
     // Find everything after the second colon.. `foo::{baz, makro};`
     let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));

compiler/rustc_resolve/src/imports.rs

@@ -114,10 +114,7 @@ crate struct Import<'a> {
 
 impl<'a> Import<'a> {
     pub fn is_glob(&self) -> bool {
-        match self.kind {
+        matches!(self.kind, ImportKind::Glob { .. })
-            ImportKind::Glob { .. } => true,
-            _ => false,
-        }
     }
 
     pub fn is_nested(&self) -> bool {
@@ -898,13 +895,11 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                         let msg = "inconsistent resolution for an import";
                         self.r.session.span_err(import.span, msg);
                     }
-                } else {
+                } else if self.r.privacy_errors.is_empty() {
-                    if self.r.privacy_errors.is_empty() {
                     let msg = "cannot determine resolution for the import";
                     let msg_note = "import resolution is stuck, try simplifying other imports";
                     self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
                 }
-                }
 
                 module
             }
@@ -1044,19 +1039,14 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                             if res != initial_res && this.ambiguity_errors.is_empty() {
                                 span_bug!(import.span, "inconsistent resolution for an import");
                             }
-                        } else {
+                        } else if res != Res::Err
-                            if res != Res::Err
                             && this.ambiguity_errors.is_empty()
                             && this.privacy_errors.is_empty()
                         {
                             let msg = "cannot determine resolution for the import";
                             let msg_note =
                                 "import resolution is stuck, try simplifying other imports";
-                                this.session
+                            this.session.struct_span_err(import.span, msg).note(msg_note).emit();
-                                    .struct_span_err(import.span, msg)
-                                    .note(msg_note)
-                                    .emit();
-                            }
                         }
                     }
                     Err(..) => {

compiler/rustc_resolve/src/late.rs

@@ -257,16 +257,12 @@ impl<'a> PathSource<'a> {
     }
 
     fn is_call(self) -> bool {
-        match self {
+        matches!(self, PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })))
-            PathSource::Expr(Some(&Expr { kind: ExprKind::Call(..), .. })) => true,
-            _ => false,
-        }
     }
 
     crate fn is_expected(self, res: Res) -> bool {
         match self {
-            PathSource::Type => match res {
+            PathSource::Type => matches!(res, Res::Def(
-                Res::Def(
                     DefKind::Struct
                     | DefKind::Union
                     | DefKind::Enum
@@ -280,19 +276,12 @@ impl<'a> PathSource<'a> {
                     _,
                 )
                 | Res::PrimTy(..)
-                | Res::SelfTy(..) => true,
+                | Res::SelfTy(..)),
-                _ => false,
+            PathSource::Trait(AliasPossibility::No) => matches!(res, Res::Def(DefKind::Trait, _)),
-            },
+            PathSource::Trait(AliasPossibility::Maybe) => {
-            PathSource::Trait(AliasPossibility::No) => match res {
+                matches!(res, Res::Def(DefKind::Trait | DefKind::TraitAlias, _))
-                Res::Def(DefKind::Trait, _) => true,
+            }
-                _ => false,
+            PathSource::Expr(..) => matches!(res, Res::Def(
-            },
-            PathSource::Trait(AliasPossibility::Maybe) => match res {
-                Res::Def(DefKind::Trait | DefKind::TraitAlias, _) => true,
-                _ => false,
-            },
-            PathSource::Expr(..) => match res {
-                Res::Def(
                     DefKind::Ctor(_, CtorKind::Const | CtorKind::Fn)
                     | DefKind::Const
                     | DefKind::Static
@@ -303,23 +292,16 @@ impl<'a> PathSource<'a> {
                     _,
                 )
                 | Res::Local(..)
-                | Res::SelfCtor(..) => true,
+                | Res::SelfCtor(..)),
-                _ => false,
+            PathSource::Pat => matches!(res, Res::Def(
-            },
-            PathSource::Pat => match res {
-                Res::Def(
                     DefKind::Ctor(_, CtorKind::Const) | DefKind::Const | DefKind::AssocConst,
                     _,
                 )
-                | Res::SelfCtor(..) => true,
+                | Res::SelfCtor(..)),
-                _ => false,
+            PathSource::TupleStruct(..) => {
-            },
+                matches!(res, Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..))
-            PathSource::TupleStruct(..) => match res {
+            }
-                Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) | Res::SelfCtor(..) => true,
+            PathSource::Struct => matches!(res, Res::Def(
-                _ => false,
-            },
-            PathSource::Struct => match res {
-                Res::Def(
                     DefKind::Struct
                     | DefKind::Union
                     | DefKind::Variant
@@ -327,9 +309,7 @@ impl<'a> PathSource<'a> {
                     | DefKind::AssocTy,
                     _,
                 )
-                | Res::SelfTy(..) => true,
+                | Res::SelfTy(..)),
-                _ => false,
-            },
             PathSource::TraitItem(ns) => match res {
                 Res::Def(DefKind::AssocConst | DefKind::AssocFn, _) if ns == ValueNS => true,
                 Res::Def(DefKind::AssocTy, _) if ns == TypeNS => true,
@@ -1450,10 +1430,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
     }
 
     fn is_base_res_local(&self, nid: NodeId) -> bool {
-        match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) {
+        matches!(self.r.partial_res_map.get(&nid).map(|res| res.base_res()), Some(Res::Local(..)))
-            Some(Res::Local(..)) => true,
-            _ => false,
-        }
     }
 
     /// Checks that all of the arms in an or-pattern have exactly the

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -702,10 +702,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 _ => break,
             }
         }
-        let followed_by_brace = match sm.span_to_snippet(sp) {
+        let followed_by_brace = matches!(sm.span_to_snippet(sp), Ok(ref snippet) if snippet == "{");
-            Ok(ref snippet) if snippet == "{" => true,
-            _ => false,
-        };
         // In case this could be a struct literal that needs to be surrounded
         // by parentheses, find the appropriate span.
         let mut i = 0;
@@ -1788,12 +1785,11 @@ impl<'tcx> LifetimeContext<'_, 'tcx> {
                         }
                         msg = "consider introducing a named lifetime parameter".to_string();
                         should_break = true;
-                        if let Some(param) = generics.params.iter().find(|p| match p.kind {
+                        if let Some(param) = generics.params.iter().find(|p| {
-                            hir::GenericParamKind::Type {
+                            !matches!(p.kind, hir::GenericParamKind::Type {
                                 synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
                                 ..
-                            } => false,
+                            })
-                            _ => true,
                         }) {
                             (param.span.shrink_to_lo(), "'a, ".to_string())
                         } else {

compiler/rustc_resolve/src/late/lifetimes.rs

@@ -351,10 +351,7 @@ fn krate(tcx: TyCtxt<'_>) -> NamedRegionMap {
 /// We have to account for this when computing the index of the other generic parameters.
 /// This function returns whether there is such an implicit parameter defined on the given item.
 fn sub_items_have_self_param(node: &hir::ItemKind<'_>) -> bool {
-    match *node {
+    matches!(*node, hir::ItemKind::Trait(..) | hir::ItemKind::TraitAlias(..))
-        hir::ItemKind::Trait(..) | hir::ItemKind::TraitAlias(..) => true,
-        _ => false,
-    }
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
@@ -417,10 +414,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
 
                 // Impls permit `'_` to be used and it is equivalent to "some fresh lifetime name".
                 // This is not true for other kinds of items.x
-                let track_lifetime_uses = match item.kind {
+                let track_lifetime_uses = matches!(item.kind, hir::ItemKind::Impl { .. });
-                    hir::ItemKind::Impl { .. } => true,
-                    _ => false,
-                };
                 // These kinds of items have only early-bound lifetime parameters.
                 let mut index = if sub_items_have_self_param(&item.kind) {
                     1 // Self comes before lifetimes
@@ -970,10 +964,10 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
 
         let trait_ref_hack = take(&mut self.trait_ref_hack);
         if !trait_ref_hack
-            || trait_ref.bound_generic_params.iter().any(|param| match param.kind {
+            || trait_ref
-                GenericParamKind::Lifetime { .. } => true,
+                .bound_generic_params
-                _ => false,
+                .iter()
-            })
+                .any(|param| matches!(param.kind, GenericParamKind::Lifetime { .. }))
         {
             if trait_ref_hack {
                 struct_span_err!(
@@ -1384,8 +1378,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                 }
                 if in_band {
                     Some(param.span)
-                } else {
+                } else if generics.params.len() == 1 {
-                    if generics.params.len() == 1 {
                     // if sole lifetime, remove the entire `<>` brackets
                     Some(generics.span)
                 } else {
@@ -1397,7 +1390,6 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                         Some(param.span.to(generics.params[i + 1].span.shrink_to_lo()))
                     }
                 }
-                }
             } else {
                 None
             }
@@ -2047,10 +2039,8 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
         //
         // This is intended to leave room for us to implement the
         // correct behavior in the future.
-        let has_lifetime_parameter = generic_args.args.iter().any(|arg| match arg {
+        let has_lifetime_parameter =
-            GenericArg::Lifetime(_) => true,
+            generic_args.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_)));
-            _ => false,
-        });
 
         // Resolve lifetimes found in the type `XX` from `Item = XX` bindings.
         for b in generic_args.bindings {

compiler/rustc_resolve/src/lib.rs

@@ -313,8 +313,9 @@ impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
                 ItemKind::ExternCrate(_) => {}
                 // but place them before the first other item
                 _ => {
-                    if self.span.map_or(true, |span| item.span < span) {
+                    if self.span.map_or(true, |span| item.span < span)
-                        if !item.span.from_expansion() {
+                        && !item.span.from_expansion()
+                    {
                         // don't insert between attributes and an item
                         if item.attrs.is_empty() {
                             self.span = Some(item.span.shrink_to_lo());
@@ -332,7 +333,6 @@ impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
         }
     }
 }
-}
 
 /// An intermediate resolution result.
 ///
@@ -558,17 +558,11 @@ impl<'a> ModuleData<'a> {
 
     // `self` resolves to the first module ancestor that `is_normal`.
     fn is_normal(&self) -> bool {
-        match self.kind {
+        matches!(self.kind, ModuleKind::Def(DefKind::Mod, _, _))
-            ModuleKind::Def(DefKind::Mod, _, _) => true,
-            _ => false,
-        }
     }
 
     fn is_trait(&self) -> bool {
-        match self.kind {
+        matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _))
-            ModuleKind::Def(DefKind::Trait, _, _) => true,
-            _ => false,
-        }
     }
 
     fn nearest_item_scope(&'a self) -> Module<'a> {
@@ -628,10 +622,7 @@ enum NameBindingKind<'a> {
 impl<'a> NameBindingKind<'a> {
     /// Is this a name binding of a import?
     fn is_import(&self) -> bool {
-        match *self {
+        matches!(*self, NameBindingKind::Import { .. })
-            NameBindingKind::Import { .. } => true,
-            _ => false,
-        }
     }
 }
 
@@ -750,13 +741,10 @@ impl<'a> NameBinding<'a> {
     }
 
     fn is_variant(&self) -> bool {
-        match self.kind {
+        matches!(self.kind, NameBindingKind::Res(
-            NameBindingKind::Res(
                 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
                 _,
-            ) => true,
+            ))
-            _ => false,
-        }
     }
 
     fn is_extern_crate(&self) -> bool {
@@ -774,10 +762,7 @@ impl<'a> NameBinding<'a> {
     }
 
     fn is_import(&self) -> bool {
-        match self.kind {
+        matches!(self.kind, NameBindingKind::Import { .. })
-            NameBindingKind::Import { .. } => true,
-            _ => false,
-        }
     }
 
     fn is_glob_import(&self) -> bool {
@@ -788,17 +773,14 @@ impl<'a> NameBinding<'a> {
     }
 
     fn is_importable(&self) -> bool {
-        match self.res() {
+        !matches!(
-            Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _) => false,
+            self.res(),
-            _ => true,
+            Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _)
-        }
+        )
     }
 
     fn is_macro_def(&self) -> bool {
-        match self.kind {
+        matches!(self.kind, NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _))
-            NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _) => true,
-            _ => false,
-        }
     }
 
     fn macro_kind(&self) -> Option<MacroKind> {
@@ -1380,7 +1362,7 @@ impl<'a> Resolver<'a> {
         let maybe_unused_extern_crates = self.maybe_unused_extern_crates;
         let glob_map = self.glob_map;
         ResolverOutputs {
-            definitions: definitions,
+            definitions,
             cstore: Box::new(self.crate_loader.into_cstore()),
             visibilities,
             extern_crate_map,
@@ -1992,8 +1974,10 @@ impl<'a> Resolver<'a> {
                 // The macro is a proc macro derive
                 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
                     if let Some(ext) = self.get_macro_by_def_id(def_id) {
-                        if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive {
+                        if !ext.is_builtin
-                            if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
+                            && ext.macro_kind() == MacroKind::Derive
+                            && parent.expansion.outer_expn_is_descendant_of(span.ctxt())
+                        {
                             *poisoned = Some(node_id);
                             return module.parent;
                         }
@@ -2001,7 +1985,6 @@ impl<'a> Resolver<'a> {
                 }
             }
         }
-        }
 
         None
     }
@@ -2390,10 +2373,7 @@ impl<'a> Resolver<'a> {
                         _ => None,
                     };
                     let (label, suggestion) = if module_res == self.graph_root.res() {
-                        let is_mod = |res| match res {
+                        let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
-                            Res::Def(DefKind::Mod, _) => true,
-                            _ => false,
-                        };
                         // Don't look up import candidates if this is a speculative resolve
                         let mut candidates = if record_used {
                             self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod)

compiler/rustc_session/src/config.rs

@@ -2057,10 +2057,7 @@ impl PpMode {
 
     pub fn needs_analysis(&self) -> bool {
         use PpMode::*;
-        match *self {
+        matches!(*self, PpmMir | PpmMirCFG)
-            PpmMir | PpmMirCFG => true,
-            _ => false,
-        }
     }
 }
 

compiler/rustc_session/src/output.rs

@@ -199,11 +199,9 @@ pub fn invalid_output_for_target(sess: &Session, crate_type: CrateType) -> bool
             _ => {}
         }
     }
-    if !sess.target.options.executables {
+    if !sess.target.options.executables && crate_type == CrateType::Executable {
-        if crate_type == CrateType::Executable {
         return true;
     }
-    }
 
     false
 }

compiler/rustc_symbol_mangling/src/legacy.rs

@@ -326,10 +326,8 @@ impl Printer<'tcx> for SymbolPrinter<'tcx> {
     ) -> Result<Self::Path, Self::Error> {
         self = print_prefix(self)?;
 
-        let args = args.iter().cloned().filter(|arg| match arg.unpack() {
+        let args =
-            GenericArgKind::Lifetime(_) => false,
+            args.iter().cloned().filter(|arg| !matches!(arg.unpack(), GenericArgKind::Lifetime(_)));
-            _ => true,
-        });
 
         if args.clone().next().is_some() {
             self.generic_delimiters(|cx| cx.comma_sep(args))

compiler/rustc_symbol_mangling/src/lib.rs

@@ -174,10 +174,7 @@ fn compute_symbol_name(
             return tcx.sess.generate_proc_macro_decls_symbol(disambiguator);
         }
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-        match tcx.hir().get(hir_id) {
+        matches!(tcx.hir().get(hir_id), Node::ForeignItem(_))
-            Node::ForeignItem(_) => true,
-            _ => false,
-        }
     } else {
         tcx.is_foreign_item(def_id)
     };
@@ -200,16 +197,15 @@ fn compute_symbol_name(
     //   show up in the `wasm-import-name` custom attribute in LLVM IR.
     //
     // [1]: https://bugs.llvm.org/show_bug.cgi?id=44316
-    if is_foreign {
+    if is_foreign
-        if tcx.sess.target.arch != "wasm32"
+        && (tcx.sess.target.arch != "wasm32"
-            || !tcx.wasm_import_module_map(def_id.krate).contains_key(&def_id)
+            || !tcx.wasm_import_module_map(def_id.krate).contains_key(&def_id))
     {
         if let Some(name) = attrs.link_name {
             return name.to_string();
         }
         return tcx.item_name(def_id).to_string();
     }
-    }
 
     if let Some(name) = attrs.export_name {
         // Use provided name
@@ -234,10 +230,7 @@ fn compute_symbol_name(
         // codegen units) then this symbol may become an exported (but hidden
         // visibility) symbol. This means that multiple crates may do the same
         // and we want to be sure to avoid any symbol conflicts here.
-        match MonoItem::Fn(instance).instantiation_mode(tcx) {
+        matches!(MonoItem::Fn(instance).instantiation_mode(tcx), InstantiationMode::GloballyShared { may_conflict: true });
-            InstantiationMode::GloballyShared { may_conflict: true } => true,
-            _ => false,
-        };
 
     let instantiating_crate =
         if avoid_cross_crate_conflicts { Some(compute_instantiating_crate()) } else { None };

compiler/rustc_target/src/abi/call/mod.rs

@@ -474,31 +474,19 @@ impl<'a, Ty> ArgAbi<'a, Ty> {
     }
 
     pub fn is_indirect(&self) -> bool {
-        match self.mode {
+        matches!(self.mode, PassMode::Indirect(..))
-            PassMode::Indirect(..) => true,
-            _ => false,
-        }
     }
 
     pub fn is_sized_indirect(&self) -> bool {
-        match self.mode {
+        matches!(self.mode, PassMode::Indirect(_, None))
-            PassMode::Indirect(_, None) => true,
-            _ => false,
-        }
     }
 
     pub fn is_unsized_indirect(&self) -> bool {
-        match self.mode {
+        matches!(self.mode, PassMode::Indirect(_, Some(_)))
-            PassMode::Indirect(_, Some(_)) => true,
-            _ => false,
-        }
     }
 
     pub fn is_ignore(&self) -> bool {
-        match self.mode {
+        matches!(self.mode, PassMode::Ignore)
-            PassMode::Ignore => true,
-            _ => false,
-        }
     }
 }
 

compiler/rustc_target/src/abi/call/riscv.rs

@@ -333,11 +333,9 @@ where
     let mut avail_gprs = 8;
     let mut avail_fprs = 8;
 
-    if !fn_abi.ret.is_ignore() {
+    if !fn_abi.ret.is_ignore() && classify_ret(cx, &mut fn_abi.ret, xlen, flen) {
-        if classify_ret(cx, &mut fn_abi.ret, xlen, flen) {
         avail_gprs -= 1;
     }
-    }
 
     for (i, arg) in fn_abi.args.iter_mut().enumerate() {
         if arg.is_ignore() {

compiler/rustc_target/src/abi/call/wasm32.rs

@@ -24,12 +24,10 @@ where
     C: LayoutOf<Ty = Ty, TyAndLayout = TyAndLayout<'a, Ty>> + HasDataLayout,
 {
     ret.extend_integer_width_to(32);
-    if ret.layout.is_aggregate() {
+    if ret.layout.is_aggregate() && !unwrap_trivial_aggregate(cx, ret) {
-        if !unwrap_trivial_aggregate(cx, ret) {
         ret.make_indirect();
     }
 }
-}
 
 fn classify_arg<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>)
 where
@@ -37,12 +35,10 @@ where
     C: LayoutOf<Ty = Ty, TyAndLayout = TyAndLayout<'a, Ty>> + HasDataLayout,
 {
     arg.extend_integer_width_to(32);
-    if arg.layout.is_aggregate() {
+    if arg.layout.is_aggregate() && !unwrap_trivial_aggregate(cx, arg) {
-        if !unwrap_trivial_aggregate(cx, arg) {
         arg.make_indirect_byval();
     }
 }
-}
 
 pub fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
 where

compiler/rustc_target/src/abi/mod.rs

@@ -557,17 +557,11 @@ impl Primitive {
     }
 
     pub fn is_float(self) -> bool {
-        match self {
+        matches!(self, F32 | F64)
-            F32 | F64 => true,
-            _ => false,
-        }
     }
 
     pub fn is_int(self) -> bool {
-        match self {
+        matches!(self, Int(..))
-            Int(..) => true,
-            _ => false,
-        }
     }
 }
 
@@ -794,18 +788,12 @@ impl Abi {
 
     /// Returns `true` if this is an uninhabited type
     pub fn is_uninhabited(&self) -> bool {
-        match *self {
+        matches!(*self, Abi::Uninhabited)
-            Abi::Uninhabited => true,
-            _ => false,
-        }
     }
 
     /// Returns `true` is this is a scalar type
     pub fn is_scalar(&self) -> bool {
-        match *self {
+        matches!(*self, Abi::Scalar(_))
-            Abi::Scalar(_) => true,
-            _ => false,
-        }
     }
 }
 

compiler/rustc_target/src/asm/mod.rs

@@ -478,10 +478,7 @@ pub enum InlineAsmType {
 
 impl InlineAsmType {
     pub fn is_integer(self) -> bool {
-        match self {
+        matches!(self, Self::I8 | Self::I16 | Self::I32 | Self::I64 | Self::I128)
-            Self::I8 | Self::I16 | Self::I32 | Self::I64 | Self::I128 => true,
-            _ => false,
-        }
     }
 
     pub fn size(self) -> Size {

compiler/rustc_traits/src/chalk/db.rs

@@ -342,29 +342,29 @@ impl<'tcx> chalk_solve::RustIrDatabase<RustInterner<'tcx>> for RustIrDatabase<'t
                 }
                 (ty::Bool, Scalar(Bool)) => true,
                 (ty::Char, Scalar(Char)) => true,
-                (ty::Int(ty1), Scalar(Int(ty2))) => match (ty1, ty2) {
+                (ty::Int(ty1), Scalar(Int(ty2))) => matches!(
+                    (ty1, ty2),
                     (ast::IntTy::Isize, chalk_ir::IntTy::Isize)
                         | (ast::IntTy::I8, chalk_ir::IntTy::I8)
                         | (ast::IntTy::I16, chalk_ir::IntTy::I16)
                         | (ast::IntTy::I32, chalk_ir::IntTy::I32)
                         | (ast::IntTy::I64, chalk_ir::IntTy::I64)
-                    | (ast::IntTy::I128, chalk_ir::IntTy::I128) => true,
+                        | (ast::IntTy::I128, chalk_ir::IntTy::I128)
-                    _ => false,
+                ),
-                },
+                (ty::Uint(ty1), Scalar(Uint(ty2))) => matches!(
-                (ty::Uint(ty1), Scalar(Uint(ty2))) => match (ty1, ty2) {
+                    (ty1, ty2),
                     (ast::UintTy::Usize, chalk_ir::UintTy::Usize)
                         | (ast::UintTy::U8, chalk_ir::UintTy::U8)
                         | (ast::UintTy::U16, chalk_ir::UintTy::U16)
                         | (ast::UintTy::U32, chalk_ir::UintTy::U32)
                         | (ast::UintTy::U64, chalk_ir::UintTy::U64)
-                    | (ast::UintTy::U128, chalk_ir::UintTy::U128) => true,
+                        | (ast::UintTy::U128, chalk_ir::UintTy::U128)
-                    _ => false,
+                ),
-                },
+                (ty::Float(ty1), Scalar(Float(ty2))) => matches!(
-                (ty::Float(ty1), Scalar(Float(ty2))) => match (ty1, ty2) {
+                    (ty1, ty2),
                     (ast::FloatTy::F32, chalk_ir::FloatTy::F32)
-                    | (ast::FloatTy::F64, chalk_ir::FloatTy::F64) => true,
+                        | (ast::FloatTy::F64, chalk_ir::FloatTy::F64)
-                    _ => false,
+                ),
-                },
                 (&ty::Tuple(..), Tuple(..)) => true,
                 (&ty::Array(..), Array) => true,
                 (&ty::Slice(..), Slice) => true,

compiler/rustc_traits/src/implied_outlives_bounds.rs

@@ -62,7 +62,7 @@ fn compute_implied_outlives_bounds<'tcx>(
         // unresolved inference variables here anyway, but there might be
         // during typeck under some circumstances.)
         let obligations = wf::obligations(infcx, param_env, hir::CRATE_HIR_ID, 0, arg, DUMMY_SP)
-            .unwrap_or(vec![]);
+            .unwrap_or_default();
 
         // N.B., all of these predicates *ought* to be easily proven
         // true. In fact, their correctness is (mostly) implied by