Add rustdoc-ui test suite

src/test/rustdoc-ui/intra-links-warning.rs

@@ -0,0 +1,19 @@
+// Copyright 2018 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.
+
+#![deny(warnings)]
+
+// must-compile-successfully
+
+//! Test with [Foo::baz], [Bar::foo], [Uniooon::X]
+
+pub struct Foo {
+    pub bar: usize,
+}

src/test/rustdoc-ui/intra-links-warning.stderr

@@ -0,0 +1,6 @@
+warning: [Foo::baz] cannot be resolved, ignoring it...
+
+warning: [Bar::foo] cannot be resolved, ignoring it...
+
+warning: [Uniooon::X] cannot be resolved, ignoring it...
+