Merging upstream version 1.66.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 137 insertions, 152 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index d86db8f8b..4ef43735a 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -1112,24 +1112,6 @@ pub struct Expr {
 }
 
 impl Expr {
-    /// Returns `true` if this expression would be valid somewhere that expects a value;
-    /// for example, an `if` condition.
-    pub fn returns(&self) -> bool {
-        if let ExprKind::Block(ref block, _) = self.kind {
-            match block.stmts.last().map(|last_stmt| &last_stmt.kind) {
-                // Implicit return
-                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,
-            }
-        } else {
-            // This is not a block, it is a value.
-            true
-        }
-    }
-
     /// Is this expr either `N`, or `{ N }`.
     ///
     /// If this is not the case, name resolution does not resolve `N` when using
@@ -1338,14 +1320,13 @@ pub enum ExprKind {
     ///
     /// The `PathSegment` represents the method name and its generic arguments
     /// (within the angle brackets).
-    /// The first element of the vector of an `Expr` is the expression that evaluates
-    /// to the object on which the method is being called on (the receiver),
-    /// and the remaining elements are the rest of the arguments.
-    /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
-    /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d])`.
+    /// The standalone `Expr` is the receiver expression.
+    /// The vector of `Expr` is the arguments.
+    /// `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
+    /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, x, [a, b, c, d])`.
     /// This `Span` is the span of the function, without the dot and receiver
     /// (e.g. `foo(a, b)` in `x.foo(a, b)`
-    MethodCall(PathSegment, Vec<P<Expr>>, Span),
+    MethodCall(PathSegment, P<Expr>, Vec<P<Expr>>, Span),
     /// A tuple (e.g., `(a, b, c, d)`).
     Tup(Vec<P<Expr>>),
     /// A binary operation (e.g., `a + b`, `a * b`).
@@ -2957,7 +2938,7 @@ pub enum AssocItemKind {
     /// An associated function.
     Fn(Box<Fn>),
     /// An associated type.
-    TyAlias(Box<TyAlias>),
+    Type(Box<TyAlias>),
     /// A macro expanding to associated items.
     MacCall(P<MacCall>),
 }
@@ -2967,7 +2948,7 @@ impl AssocItemKind {
         match *self {
             Self::Const(defaultness, ..)
             | Self::Fn(box Fn { defaultness, .. })
-            | Self::TyAlias(box TyAlias { defaultness, .. }) => defaultness,
+            | Self::Type(box TyAlias { defaultness, .. }) => defaultness,
             Self::MacCall(..) => Defaultness::Final,
         }
     }
@@ -2978,7 +2959,7 @@ impl From<AssocItemKind> for ItemKind {
         match assoc_item_kind {
             AssocItemKind::Const(a, b, c) => ItemKind::Const(a, b, c),
             AssocItemKind::Fn(fn_kind) => ItemKind::Fn(fn_kind),
-            AssocItemKind::TyAlias(ty_alias_kind) => ItemKind::TyAlias(ty_alias_kind),
+            AssocItemKind::Type(ty_alias_kind) => ItemKind::TyAlias(ty_alias_kind),
             AssocItemKind::MacCall(a) => ItemKind::MacCall(a),
         }
     }
@@ -2991,7 +2972,7 @@ impl TryFrom<ItemKind> for AssocItemKind {
         Ok(match item_kind {
             ItemKind::Const(a, b, c) => AssocItemKind::Const(a, b, c),
             ItemKind::Fn(fn_kind) => AssocItemKind::Fn(fn_kind),
-            ItemKind::TyAlias(ty_alias_kind) => AssocItemKind::TyAlias(ty_alias_kind),
+            ItemKind::TyAlias(ty_kind) => AssocItemKind::Type(ty_kind),
             ItemKind::MacCall(a) => AssocItemKind::MacCall(a),
             _ => return Err(item_kind),
         })
@@ -3043,14 +3024,13 @@ pub type ForeignItem = Item<ForeignItemKind>;
 mod size_asserts {
     use super::*;
     use rustc_data_structures::static_assert_size;
-    // These are in alphabetical order, which is easy to maintain.
+    // tidy-alphabetical-start
     static_assert_size!(AssocItem, 104);
     static_assert_size!(AssocItemKind, 32);
     static_assert_size!(Attribute, 32);
     static_assert_size!(Block, 48);
     static_assert_size!(Expr, 104);
     static_assert_size!(ExprKind, 72);
-    #[cfg(not(bootstrap))]
     static_assert_size!(Fn, 184);
     static_assert_size!(ForeignItem, 96);
     static_assert_size!(ForeignItemKind, 24);
@@ -3065,11 +3045,12 @@ mod size_asserts {
     static_assert_size!(Local, 72);
     static_assert_size!(Param, 40);
     static_assert_size!(Pat, 120);
-    static_assert_size!(PatKind, 96);
     static_assert_size!(Path, 40);
     static_assert_size!(PathSegment, 24);
+    static_assert_size!(PatKind, 96);
     static_assert_size!(Stmt, 32);
     static_assert_size!(StmtKind, 16);
     static_assert_size!(Ty, 96);
     static_assert_size!(TyKind, 72);
+    // tidy-alphabetical-end
 }
diff --git a/compiler/rustc_ast/src/lib.rs b/compiler/rustc_ast/src/lib.rs
index bd7a85b07..eeb7e56e2 100644
--- a/compiler/rustc_ast/src/lib.rs
+++ b/compiler/rustc_ast/src/lib.rs
@@ -13,9 +13,7 @@
 #![feature(const_default_impls)]
 #![feature(const_trait_impl)]
 #![feature(if_let_guard)]
-#![cfg_attr(bootstrap, feature(label_break_value))]
 #![feature(let_chains)]
-#![cfg_attr(bootstrap, feature(let_else))]
 #![feature(min_specialization)]
 #![feature(negative_impls)]
 #![feature(slice_internals)]
diff --git a/compiler/rustc_ast/src/mut_visit.rs b/compiler/rustc_ast/src/mut_visit.rs
index 9fd0b63c4..b970e57e0 100644
--- a/compiler/rustc_ast/src/mut_visit.rs
+++ b/compiler/rustc_ast/src/mut_visit.rs
@@ -152,6 +152,12 @@ pub trait MutVisitor: Sized {
         noop_visit_expr(e, self);
     }
 
+    /// This method is a hack to workaround unstable of `stmt_expr_attributes`.
+    /// It can be removed once that feature is stabilized.
+    fn visit_method_receiver_expr(&mut self, ex: &mut P<Expr>) {
+        self.visit_expr(ex)
+    }
+
     fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
         noop_filter_map_expr(e, self)
     }
@@ -1106,7 +1112,7 @@ pub fn noop_flat_map_assoc_item<T: MutVisitor>(
             visit_fn_sig(sig, visitor);
             visit_opt(body, |body| visitor.visit_block(body));
         }
-        AssocItemKind::TyAlias(box TyAlias {
+        AssocItemKind::Type(box TyAlias {
             defaultness,
             generics,
             where_clauses,
@@ -1297,10 +1303,11 @@ pub fn noop_visit_expr<T: MutVisitor>(
             vis.visit_expr(f);
             visit_exprs(args, vis);
         }
-        ExprKind::MethodCall(PathSegment { ident, id, args }, exprs, span) => {
+        ExprKind::MethodCall(PathSegment { ident, id, args }, receiver, exprs, span) => {
             vis.visit_ident(ident);
             vis.visit_id(id);
             visit_opt(args, |args| vis.visit_generic_args(args));
+            vis.visit_method_receiver_expr(receiver);
             visit_exprs(exprs, vis);
             vis.visit_span(span);
         }
@@ -1588,3 +1595,9 @@ impl DummyAstNode for Crate {
         }
     }
 }
+
+impl<N: DummyAstNode, T: DummyAstNode> DummyAstNode for crate::ast_traits::AstNodeWrapper<N, T> {
+    fn dummy() -> Self {
+        crate::ast_traits::AstNodeWrapper::new(N::dummy(), T::dummy())
+    }
+}
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index 97dfb7837..83b10d906 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -13,7 +13,7 @@ use rustc_span::symbol::{kw, sym};
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::{self, edition::Edition, Span, DUMMY_SP};
 use std::borrow::Cow;
-use std::{fmt, mem};
+use std::fmt;
 
 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub enum CommentKind {
@@ -256,10 +256,6 @@ pub enum TokenKind {
     Eof,
 }
 
-// `TokenKind` is used a lot. Make sure it doesn't unintentionally get bigger.
-#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(TokenKind, 16);
-
 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub struct Token {
     pub kind: TokenKind,
@@ -335,11 +331,6 @@ impl Token {
         Token::new(Ident(ident.name, ident.is_raw_guess()), ident.span)
     }
 
-    /// Return this token by value and leave a dummy token in its place.
-    pub fn take(&mut self) -> Self {
-        mem::replace(self, Token::dummy())
-    }
-
     /// For interpolated tokens, returns a span of the fragment to which the interpolated
     /// token refers. For all other tokens this is just a regular span.
     /// It is particularly important to use this for identifiers and lifetimes
@@ -354,17 +345,14 @@ impl Token {
     }
 
     pub fn is_op(&self) -> bool {
-        !matches!(
-            self.kind,
-            OpenDelim(..)
-                | CloseDelim(..)
-                | Literal(..)
-                | DocComment(..)
-                | Ident(..)
-                | Lifetime(..)
-                | Interpolated(..)
-                | Eof
-        )
+        match self.kind {
+            Eq | Lt | Le | EqEq | Ne | Ge | Gt | AndAnd | OrOr | Not | Tilde | BinOp(_)
+            | BinOpEq(_) | At | Dot | DotDot | DotDotDot | DotDotEq | Comma | Semi | Colon
+            | ModSep | RArrow | LArrow | FatArrow | Pound | Dollar | Question | SingleQuote => true,
+
+            OpenDelim(..) | CloseDelim(..) | Literal(..) | DocComment(..) | Ident(..)
+            | Lifetime(..) | Interpolated(..) | Eof => false,
+        }
     }
 
     pub fn is_like_plus(&self) -> bool {
@@ -733,6 +721,7 @@ impl Token {
 }
 
 impl PartialEq<TokenKind> for Token {
+    #[inline]
     fn eq(&self, rhs: &TokenKind) -> bool {
         self.kind == *rhs
     }
@@ -756,10 +745,6 @@ pub enum Nonterminal {
     NtVis(P<ast::Visibility>),
 }
 
-// `Nonterminal` is used a lot. Make sure it doesn't unintentionally get bigger.
-#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(Nonterminal, 16);
-
 #[derive(Debug, Copy, Clone, PartialEq, Encodable, Decodable)]
 pub enum NonterminalKind {
     Item,
@@ -898,3 +883,17 @@ where
         panic!("interpolated tokens should not be present in the HIR")
     }
 }
+
+// Some types are used a lot. Make sure they don't unintentionally get bigger.
+#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
+mod size_asserts {
+    use super::*;
+    use rustc_data_structures::static_assert_size;
+    // tidy-alphabetical-start
+    static_assert_size!(Lit, 12);
+    static_assert_size!(LitKind, 2);
+    static_assert_size!(Nonterminal, 16);
+    static_assert_size!(Token, 24);
+    static_assert_size!(TokenKind, 16);
+    // tidy-alphabetical-end
+}
diff --git a/compiler/rustc_ast/src/tokenstream.rs b/compiler/rustc_ast/src/tokenstream.rs
index 875cd620d..015f5c1ee 100644
--- a/compiler/rustc_ast/src/tokenstream.rs
+++ b/compiler/rustc_ast/src/tokenstream.rs
@@ -47,10 +47,6 @@ pub enum TokenTree {
     Delimited(DelimSpan, Delimiter, TokenStream),
 }
 
-// This type is used a lot. Make sure it doesn't unintentionally get bigger.
-#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(TokenTree, 32);
-
 // Ensure all fields of `TokenTree` is `Send` and `Sync`.
 #[cfg(parallel_compiler)]
 fn _dummy()
@@ -249,12 +245,12 @@ impl AttrTokenStream {
                                 // properly implemented - we always synthesize fake tokens,
                                 // so we never reach this code.
 
-                                let mut builder = TokenStreamBuilder::new();
+                                let mut stream = TokenStream::default();
                                 for inner_attr in inner_attrs {
-                                    builder.push(inner_attr.tokens());
+                                    stream.push_stream(inner_attr.tokens());
                                 }
-                                builder.push(delim_tokens.clone());
-                                *tree = TokenTree::Delimited(*span, *delim, builder.build());
+                                stream.push_stream(delim_tokens.clone());
+                                *tree = TokenTree::Delimited(*span, *delim, stream);
                                 found = true;
                                 break;
                             }
@@ -308,13 +304,20 @@ pub struct AttributesData {
 #[derive(Clone, Debug, Default, Encodable, Decodable)]
 pub struct TokenStream(pub(crate) Lrc<Vec<TokenTree>>);
 
-// `TokenStream` is used a lot. Make sure it doesn't unintentionally get bigger.
-#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(TokenStream, 8);
-
+/// Similar to `proc_macro::Spacing`, but for tokens.
+///
+/// Note that all `ast::TokenTree::Token` instances have a `Spacing`, but when
+/// we convert to `proc_macro::TokenTree` for proc macros only `Punct`
+/// `TokenTree`s have a `proc_macro::Spacing`.
 #[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
 pub enum Spacing {
+    /// The token is not immediately followed by an operator token (as
+    /// determined by `Token::is_op`). E.g. a `+` token is `Alone` in `+ =`,
+    /// `+/*foo*/=`, `+ident`, and `+()`.
     Alone,
+
+    /// The token is immediately followed by an operator token. E.g. a `+`
+    /// token is `Joint` in `+=` and `++`.
     Joint,
 }
 
@@ -502,76 +505,49 @@ impl TokenStream {
 
         self.trees().map(|tree| TokenStream::flatten_token_tree(tree)).collect()
     }
-}
 
-// 99.5%+ of the time we have 1 or 2 elements in this vector.
-#[derive(Clone)]
-pub struct TokenStreamBuilder(SmallVec<[TokenStream; 2]>);
-
-impl TokenStreamBuilder {
-    pub fn new() -> TokenStreamBuilder {
-        TokenStreamBuilder(SmallVec::new())
-    }
-
-    pub fn push(&mut self, stream: TokenStream) {
-        self.0.push(stream);
-    }
-
-    pub fn build(self) -> TokenStream {
-        let mut streams = self.0;
-        match streams.len() {
-            0 => TokenStream::default(),
-            1 => streams.pop().unwrap(),
-            _ => {
-                // We will extend the first stream in `streams` with the
-                // elements from the subsequent streams. This requires using
-                // `make_mut()` on the first stream, and in practice this
-                // doesn't cause cloning 99.9% of the time.
-                //
-                // One very common use case is when `streams` has two elements,
-                // where the first stream has any number of elements within
-                // (often 1, but sometimes many more) and the second stream has
-                // a single element within.
-
-                // Determine how much the first stream will be extended.
-                // Needed to avoid quadratic blow up from on-the-fly
-                // reallocations (#57735).
-                let num_appends = streams.iter().skip(1).map(|ts| ts.len()).sum();
-
-                // Get the first stream, which will become the result stream.
-                // If it's `None`, create an empty stream.
-                let mut iter = streams.into_iter();
-                let mut res_stream_lrc = iter.next().unwrap().0;
-
-                // Append the subsequent elements to the result stream, after
-                // reserving space for them.
-                let res_vec_mut = Lrc::make_mut(&mut res_stream_lrc);
-                res_vec_mut.reserve(num_appends);
-                for stream in iter {
-                    let stream_iter = stream.0.iter().cloned();
-
-                    // If (a) `res_mut_vec` is not empty and the last tree
-                    // within it is a token tree marked with `Joint`, and (b)
-                    // `stream` is not empty and the first tree within it is a
-                    // token tree, and (c) the two tokens can be glued
-                    // together...
-                    if let Some(TokenTree::Token(last_tok, Spacing::Joint)) = res_vec_mut.last()
-                        && let Some(TokenTree::Token(tok, spacing)) = stream.0.first()
-                        && let Some(glued_tok) = last_tok.glue(&tok)
-                    {
-                        // ...then overwrite the last token tree in
-                        // `res_vec_mut` with the glued token, and skip the
-                        // first token tree from `stream`.
-                        *res_vec_mut.last_mut().unwrap() = TokenTree::Token(glued_tok, *spacing);
-                        res_vec_mut.extend(stream_iter.skip(1));
-                    } else {
-                        // Append all of `stream`.
-                        res_vec_mut.extend(stream_iter);
-                    }
-                }
+    // If `vec` is not empty, try to glue `tt` onto its last token. The return
+    // value indicates if gluing took place.
+    fn try_glue_to_last(vec: &mut Vec<TokenTree>, tt: &TokenTree) -> bool {
+        if let Some(TokenTree::Token(last_tok, Spacing::Joint)) = vec.last()
+            && let TokenTree::Token(tok, spacing) = tt
+            && let Some(glued_tok) = last_tok.glue(&tok)
+        {
+            // ...then overwrite the last token tree in `vec` with the
+            // glued token, and skip the first token tree from `stream`.
+            *vec.last_mut().unwrap() = TokenTree::Token(glued_tok, *spacing);
+            true
+        } else {
+            false
+        }
+    }
 
-                TokenStream(res_stream_lrc)
-            }
+    // Push `tt` onto the end of the stream, possibly gluing it to the last
+    // token. Uses `make_mut` to maximize efficiency.
+    pub fn push_tree(&mut self, tt: TokenTree) {
+        let vec_mut = Lrc::make_mut(&mut self.0);
+
+        if Self::try_glue_to_last(vec_mut, &tt) {
+            // nothing else to do
+        } else {
+            vec_mut.push(tt);
+        }
+    }
+
+    // Push `stream` onto the end of the stream, possibly gluing the first
+    // token tree to the last token. (No other token trees will be glued.)
+    // Uses `make_mut` to maximize efficiency.
+    pub fn push_stream(&mut self, stream: TokenStream) {
+        let vec_mut = Lrc::make_mut(&mut self.0);
+
+        let stream_iter = stream.0.iter().cloned();
+
+        if let Some(first) = stream.0.first() && Self::try_glue_to_last(vec_mut, first) {
+            // Now skip the first token tree from `stream`.
+            vec_mut.extend(stream_iter.skip(1));
+        } else {
+            // Append all of `stream`.
+            vec_mut.extend(stream_iter);
         }
     }
 }
@@ -664,3 +640,17 @@ impl DelimSpan {
         self.open.with_hi(self.close.hi())
     }
 }
+
+// Some types are used a lot. Make sure they don't unintentionally get bigger.
+#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
+mod size_asserts {
+    use super::*;
+    use rustc_data_structures::static_assert_size;
+    // tidy-alphabetical-start
+    static_assert_size!(AttrTokenStream, 8);
+    static_assert_size!(AttrTokenTree, 32);
+    static_assert_size!(LazyAttrTokenStream, 8);
+    static_assert_size!(TokenStream, 8);
+    static_assert_size!(TokenTree, 32);
+    // tidy-alphabetical-end
+}
diff --git a/compiler/rustc_ast/src/util/parser.rs b/compiler/rustc_ast/src/util/parser.rs
index 6c5c7f66f..b40ad6f70 100644
--- a/compiler/rustc_ast/src/util/parser.rs
+++ b/compiler/rustc_ast/src/util/parser.rs
@@ -396,9 +396,9 @@ pub fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
             contains_exterior_struct_lit(&x)
         }
 
-        ast::ExprKind::MethodCall(.., ref exprs, _) => {
+        ast::ExprKind::MethodCall(_, ref receiver, _, _) => {
             // X { y: 1 }.bar(...)
-            contains_exterior_struct_lit(&exprs[0])
+            contains_exterior_struct_lit(&receiver)
         }
 
         _ => false,
diff --git a/compiler/rustc_ast/src/visit.rs b/compiler/rustc_ast/src/visit.rs
index 1d0de5a4b..6f56c1ef0 100644
--- a/compiler/rustc_ast/src/visit.rs
+++ b/compiler/rustc_ast/src/visit.rs
@@ -140,6 +140,11 @@ pub trait Visitor<'ast>: Sized {
     fn visit_expr(&mut self, ex: &'ast Expr) {
         walk_expr(self, ex)
     }
+    /// This method is a hack to workaround unstable of `stmt_expr_attributes`.
+    /// It can be removed once that feature is stabilized.
+    fn visit_method_receiver_expr(&mut self, ex: &'ast Expr) {
+        self.visit_expr(ex)
+    }
     fn visit_expr_post(&mut self, _ex: &'ast Expr) {}
     fn visit_ty(&mut self, t: &'ast Ty) {
         walk_ty(self, t)
@@ -244,14 +249,12 @@ pub trait Visitor<'ast>: Sized {
 
 #[macro_export]
 macro_rules! walk_list {
-    ($visitor: expr, $method: ident, $list: expr) => {
-        for elem in $list {
-            $visitor.$method(elem)
-        }
-    };
-    ($visitor: expr, $method: ident, $list: expr, $($extra_args: expr),*) => {
-        for elem in $list {
-            $visitor.$method(elem, $($extra_args,)*)
+    ($visitor: expr, $method: ident, $list: expr $(, $($extra_args: expr),* )?) => {
+        {
+            #[cfg_attr(not(bootstrap), allow(for_loops_over_fallibles))]
+            for elem in $list {
+                $visitor.$method(elem $(, $($extra_args,)* )?)
+            }
         }
     }
 }
@@ -685,7 +688,7 @@ pub fn walk_assoc_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem,
             let kind = FnKind::Fn(FnCtxt::Assoc(ctxt), ident, sig, vis, generics, body.as_deref());
             visitor.visit_fn(kind, span, id);
         }
-        AssocItemKind::TyAlias(box TyAlias { generics, bounds, ty, .. }) => {
+        AssocItemKind::Type(box TyAlias { generics, bounds, ty, .. }) => {
             visitor.visit_generics(generics);
             walk_list!(visitor, visit_param_bound, bounds, BoundKind::Bound);
             walk_list!(visitor, visit_ty, ty);
@@ -795,8 +798,9 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
             visitor.visit_expr(callee_expression);
             walk_list!(visitor, visit_expr, arguments);
         }
-        ExprKind::MethodCall(ref segment, ref arguments, _span) => {
+        ExprKind::MethodCall(ref segment, ref receiver, ref arguments, _span) => {
             visitor.visit_path_segment(segment);
+            visitor.visit_expr(receiver);
             walk_list!(visitor, visit_expr, arguments);
         }
         ExprKind::Binary(_, ref left_expression, ref right_expression) => {