Added help for eof message inside macro invocation

Fixes rust-lang#27569

Author: gchp

src/libsyntax/parse/parser.rs

@@ -2440,6 +2440,13 @@ impl<'a> Parser<'a> {
                             err.cancel();
                             let msg = format!("expected expression, found {}",
                                               self.this_token_descr());
+                            if self.token == token::Token::Eof {
+                                let help = format!("{} in this context refers \
+                                                   to the end of the macro invocation",
+                                                   self.this_token_descr());
+                                return Err(self.span_fatal_help(
+                                    self.span, &msg, &help));
+                            }
                             return Err(self.fatal(&msg));
                         }
                     }

src/test/parse-fail/macro-eof-message.rs

@@ -0,0 +1,16 @@
+// 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.
+
+
+fn main() {
+    let message = "test";
+    println!("{}", message/); //~ ERROR expected expression, found `<eof>`
+    //~^ HELP `<eof>` in this context refers to the end of the macro invocation
+}