Add some tests around associated types

src/test/ui/existential_types/bound_reduction.rs

@@ -0,0 +1,30 @@
+// 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.
+
+// compile-pass
+
+#![allow(warnings)]
+
+#![feature(existential_type)]
+
+fn main() {
+}
+
+existential type Foo<V>: std::fmt::Debug;
+
+trait Trait<U> {}
+
+fn foo_desugared<T: Trait<[u32; {
+    #[no_mangle]
+    static FOO: usize = 42;
+    3
+}]>>(_: T) -> Foo<T> {
+    (42, std::marker::PhantomData::<T>)
+}

src/test/ui/existential_types/bound_reduction2.rs

@@ -0,0 +1,28 @@
+// 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(existential_type)]
+
+fn main() {
+}
+
+trait TraitWithAssoc {
+    type Assoc;
+}
+
+existential type Foo<V>: Trait<V>;
+
+trait Trait<U> {}
+
+impl<W> Trait<W> for () {}
+
+fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> { //~ ERROR non-defining
+    ()
+}

src/test/ui/existential_types/bound_reduction2.stderr

@@ -0,0 +1,16 @@
+error: non-defining existential type use in defining scope
+  --> $DIR/bound_reduction2.rs:26:1
+   |
+LL | / fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> { //~ ERROR non-defining
+LL | |     ()
+LL | | }
+   | |_^
+   |
+note: used non-generic type <T as TraitWithAssoc>::Assoc for generic parameter
+  --> $DIR/bound_reduction2.rs:20:22
+   |
+LL | existential type Foo<V>: Trait<V>;
+   |                      ^
+
+error: aborting due to previous error
+

src/test/ui/existential_types/no_revealing_outside_defining_module.rs

@@ -32,4 +32,4 @@ fn bomp() -> boo::Boo {
 
 fn bomp_loop() -> boo::Boo {
     loop {}
-}
+}

src/test/ui/existential_types/not_well_formed.rs

@@ -0,0 +1,28 @@
+// 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(existential_type)]
+
+fn main() {
+}
+
+trait TraitWithAssoc {
+    type Assoc;
+}
+
+existential type Foo<V>: Trait<V::Assoc>; //~ associated type `Assoc` not found for `V`
+
+trait Trait<U> {}
+
+impl<W> Trait<W> for () {}
+
+fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T> {
+    ()
+}

src/test/ui/existential_types/not_well_formed.stderr

@@ -0,0 +1,9 @@
+error[E0220]: associated type `Assoc` not found for `V`
+  --> $DIR/not_well_formed.rs:20:32
+   |
+LL | existential type Foo<V>: Trait<V::Assoc>; //~ associated type `Assoc` not found for `V`
+   |                                ^^^^^^^^ associated type `Assoc` not found
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0220`.