libsyntax: Stop parsing newtype enums

Author: pcwalton

src/libsyntax/parse/obsolete.rs

@@ -53,6 +53,7 @@ pub enum ObsoleteSyntax {
     ObsoleteRecordPattern,
     ObsoleteAssertion,
     ObsoleteBareFnType,
+    ObsoleteNewtypeEnum,
 }
 
 impl to_bytes::IterBytes for ObsoleteSyntax {
@@ -165,6 +166,10 @@ pub impl Parser {
                 "bare function type",
                 "use `&fn` or `extern fn` instead"
             ),
+            ObsoleteNewtypeEnum => (
+                "newtype enum",
+                "instead of `enum Foo = int`, write `struct Foo(int)`"
+            ),
         };
 
         self.report(sp, kind, kind_str, desc);

src/libsyntax/parse/parser.rs

@@ -77,6 +77,7 @@ use parse::obsolete::{ObsoleteTraitBoundSeparator, ObsoleteMutOwnedPointer};
 use parse::obsolete::{ObsoleteMutVector, ObsoleteTraitImplVisibility};
 use parse::obsolete::{ObsoleteRecordType, ObsoleteRecordPattern};
 use parse::obsolete::{ObsoleteAssertion, ObsoleteBareFnType};
+use parse::obsolete::{ObsoleteNewtypeEnum};
 use parse::prec::{as_prec, token_to_binop};
 use parse::token::{can_begin_expr, is_ident, is_ident_or_path};
 use parse::token::{is_plain_ident, INTERPOLATED, special_idents};
@@ -3797,6 +3798,8 @@ pub impl Parser {
                 vis: public,
             });
 
+            self.obsolete(*self.last_span, ObsoleteNewtypeEnum);
+
             return (
                 id,
                 item_enum(