Parse numeric fields in struct expressions and patterns

Author: petrochenkov

src/libsyntax/parse/parser.rs

@@ -2009,10 +2009,19 @@ impl<'a> Parser<'a> {
         }
     }
 
+    pub fn parse_field_name(&mut self) -> PResult<'a, Ident> {
+        if let token::Literal(token::Integer(name), None) = self.token {
+            self.bump();
+            Ok(Ident::with_empty_ctxt(name))
+        } else {
+            self.parse_ident()
+        }
+    }
+
     /// Parse ident COLON expr
     pub fn parse_field(&mut self) -> PResult<'a, Field> {
         let lo = self.span.lo;
-        let i = self.parse_ident()?;
+        let i = self.parse_field_name()?;
         let hi = self.last_span.hi;
         self.expect(&token::Colon)?;
         let e = self.parse_expr()?;
@@ -3508,7 +3517,7 @@ impl<'a> Parser<'a> {
             // Check if a colon exists one ahead. This means we're parsing a fieldname.
             let (subpat, fieldname, is_shorthand) = if self.look_ahead(1, |t| t == &token::Colon) {
                 // Parsing a pattern of the form "fieldname: pat"
-                let fieldname = self.parse_ident()?;
+                let fieldname = self.parse_field_name()?;
                 self.bump();
                 let pat = self.parse_pat()?;
                 hi = pat.span.hi;

src/test/compile-fail/numeric-fields.rs

@@ -0,0 +1,20 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(relaxed_adts)]
+
+struct S(u8, u16);
+
+fn main() {
+    let s = S{0b1: 10, 0: 11}; //~ ERROR structure `S` has no field named `0b1`
+    match s {
+        S{0: a, 0x1: b, ..} => {} //~ ERROR does not have a field named `0x1`
+    }
+}

src/test/run-pass/numeric-fields.rs

@@ -0,0 +1,23 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(relaxed_adts)]
+
+struct S(u8, u16);
+
+fn main() {
+    let s = S{1: 10, 0: 11};
+    match s {
+        S{0: a, 1: b, ..} => {
+            assert_eq!(a, 11);
+            assert_eq!(b, 10);
+        }
+    }
+}