libsyntax: remove dead code from parser.rs

Both `parse_tuple_struct_body` and `parse_item_struct` handled the case
of unit like struct. The redundancy is removed,
`parse_tuple_struct_body` now handles only real tuple structs.

src/libsyntax/parse/parser.rs

@@ -4769,7 +4769,7 @@ impl<'a> Parser<'a> {
                                    generics: &mut ast::Generics)
                                    -> PResult<Vec<StructField>> {
         // This is the case where we find `struct Foo<T>(T) where T: Copy;`
-        if self.check(&token::OpenDelim(token::Paren)) {
+        // Unit like structs are handled in parse_item_struct function
         let fields = try!(self.parse_unspanned_seq(
             &token::OpenDelim(token::Paren),
             &token::CloseDelim(token::Paren),
@@ -4795,17 +4795,6 @@ impl<'a> Parser<'a> {
         generics.where_clause = try!(self.parse_where_clause());
         try!(self.expect(&token::Semi));
         Ok(fields)
-        // This is the case where we just see struct Foo<T> where T: Copy;
-        } else if self.token.is_keyword(keywords::Where) {
-            generics.where_clause = try!(self.parse_where_clause());
-            try!(self.expect(&token::Semi));
-            Ok(Vec::new())
-        // This case is where we see: `struct Foo<T>;`
-        } else {
-            let token_str = self.this_token_to_string();
-            Err(self.fatal(&format!("expected `where`, `{}`, `(`, or `;` after struct \
-                name, found `{}`", "{", token_str)))
-        }
     }
 
     /// Parse a structure field declaration