Add unit test for Implemented-From-Env

Author: varkor

src/test/ui/chalkify/lower_trait.rs

@@ -0,0 +1,22 @@
+// 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.
+
+#![feature(rustc_attrs)]
+
+#[rustc_dump_program_clauses] //~ ERROR Implemented(Self: Foo<S, T, U>) :-
+trait Foo<S, T, U> {
+    fn s(S) -> S;
+    fn t(T) -> T;
+    fn u(U) -> U;
+}
+
+fn main() {
+    println!("hello");
+}

src/test/ui/chalkify/lower_trait.stderr

@@ -0,0 +1,8 @@
+error: Implemented(Self: Foo<S, T, U>) :- FromEnv(Self: Foo<S, T, U>).
+  --> $DIR/lower_trait.rs:13:1
+   |
+LL | #[rustc_dump_program_clauses] //~ ERROR Implemented(Self: Foo<S, T, U>) :-
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+