Add a failing test for errors in proc macros

This test currently fails because the tokenization of an AST item during the
expansion of a procedural macro attribute rounds-trips through strings, losing
span information.

Author: alexcrichton

src/test/compile-fail-fulldeps/proc-macro/attribute-with-error.rs

@@ -0,0 +1,25 @@
+// Copyright 2017 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.
+
+// aux-build:attribute-with-error.rs
+
+#![feature(proc_macro)]
+
+extern crate attribute_with_error;
+
+#[attribute_with_error::foo]
+fn test() {
+    let a: i32 = "foo";
+    //~^ ERROR: mismatched types
+}
+
+fn main() {
+    test();
+}

src/test/compile-fail-fulldeps/proc-macro/auxiliary/attribute-with-error.rs

@@ -0,0 +1,24 @@
+// Copyright 2017 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.
+
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+#![feature(proc_macro)]
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn foo(_attr: TokenStream, input: TokenStream) -> TokenStream {
+    input.into_iter().collect()
+}