Rollup merge of #80467 - LingMan:more_matches, r=oli-obk

More uses of the matches! macro

`@rustbot` modify labels +C-cleanup +T-compiler

Author: JohnTitor

compiler/rustc_ast/src/ast.rs

@@ -1092,15 +1092,9 @@ impl Expr {
         if let ExprKind::Block(ref block, _) = self.kind {
             match block.stmts.last().map(|last_stmt| &last_stmt.kind) {
                 // Implicit return
-                Some(&StmtKind::Expr(_)) => true,
-                Some(&StmtKind::Semi(ref expr)) => {
-                    if let ExprKind::Ret(_) = expr.kind {
-                        // Last statement is explicit return.
-                        true
-                    } else {
-                        false
-                    }
-                }
+                Some(StmtKind::Expr(_)) => true,
+                // Last statement is an explicit return?
+                Some(StmtKind::Semi(expr)) => matches!(expr.kind, ExprKind::Ret(_)),
                 // This is a block that doesn't end in either an implicit or explicit return.
                 _ => false,
             }
@@ -1950,7 +1944,7 @@ impl TyKind {
     }
 
     pub fn is_unit(&self) -> bool {
-        if let TyKind::Tup(ref tys) = *self { tys.is_empty() } else { false }
+        matches!(self, TyKind::Tup(tys) if tys.is_empty())
     }
 }
 

compiler/rustc_ast_lowering/src/lib.rs

@@ -1806,12 +1806,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             output,
             c_variadic,
             implicit_self: decl.inputs.get(0).map_or(hir::ImplicitSelfKind::None, |arg| {
-                let is_mutable_pat = match arg.pat.kind {
-                    PatKind::Ident(BindingMode::ByValue(mt) | BindingMode::ByRef(mt), _, _) => {
-                        mt == Mutability::Mut
-                    }
-                    _ => false,
-                };
+                use BindingMode::{ByRef, ByValue};
+                let is_mutable_pat = matches!(
+                    arg.pat.kind,
+                    PatKind::Ident(ByValue(Mutability::Mut) | ByRef(Mutability::Mut), ..)
+                );
 
                 match arg.ty.kind {
                     TyKind::ImplicitSelf if is_mutable_pat => hir::ImplicitSelfKind::Mut,