Improve ux when calling associated functions with dot notation

Issue: 22692

src/test/ui/resolve/issue-22692.rs

@@ -0,0 +1,13 @@
+// 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.
+
+fn main() {
+    let _ = String.new();
+}

src/test/ui/resolve/issue-22692.stderr

@@ -0,0 +1,11 @@
+error[E0423]: expected value, found struct `String`
+  --> $DIR/issue-22692.rs:12:13
+   |
+LL |     let _ = String.new();
+   |             ^^^^^^----
+   |             |
+   |             help: use `::` to access an associated function: `String::new`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0423`.