Implement `mut ref`/`mut ref mut`

1 files changed, 10 insertions, 6 deletions

diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index de83528b52c..1971591364d 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -24,12 +24,11 @@ use rustc_ast::token::{self, Delimiter, Token, TokenKind};
 use rustc_ast::tokenstream::{AttributesData, DelimSpacing, DelimSpan, Spacing};
 use rustc_ast::tokenstream::{TokenStream, TokenTree, TokenTreeCursor};
 use rustc_ast::util::case::Case;
-use rustc_ast::AttrId;
-use rustc_ast::CoroutineKind;
-use rustc_ast::DUMMY_NODE_ID;
-use rustc_ast::{self as ast, AnonConst, Const, DelimArgs, Extern};
-use rustc_ast::{AttrArgs, AttrArgsEq, Expr, ExprKind, Mutability, StrLit};
-use rustc_ast::{HasAttrs, HasTokens, Unsafe, Visibility, VisibilityKind};
+use rustc_ast::{
+    self as ast, AnonConst, AttrArgs, AttrArgsEq, AttrId, ByRef, Const, CoroutineKind, DelimArgs,
+    Expr, ExprKind, Extern, HasAttrs, HasTokens, Mutability, StrLit, Unsafe, Visibility,
+    VisibilityKind, DUMMY_NODE_ID,
+};
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::PResult;
@@ -1273,6 +1272,11 @@ impl<'a> Parser<'a> {
         if self.eat_keyword(kw::Mut) { Mutability::Mut } else { Mutability::Not }
     }
 
+    /// Parses reference binding mode (`ref`, `ref mut`, or nothing).
+    fn parse_byref(&mut self) -> ByRef {
+        if self.eat_keyword(kw::Ref) { ByRef::Yes(self.parse_mutability()) } else { ByRef::No }
+    }
+
     /// Possibly parses mutability (`const` or `mut`).
     fn parse_const_or_mut(&mut self) -> Option<Mutability> {
         if self.eat_keyword(kw::Mut) {