Add const and static TAIT tests

src/test/ui/type-alias-impl-trait/static-const-types.rs

@@ -0,0 +1,16 @@
+#![feature(type_alias_impl_trait)]
+#![allow(dead_code)]
+
+// FIXME: This should compile, but it currently doesn't
+
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+//~^ ERROR: could not find defining uses
+
+static FOO1: Foo = 22_u32;
+//~^ ERROR: mismatched types [E0308]
+const FOO2: Foo = 22_u32;
+//~^ ERROR: mismatched types [E0308]
+
+fn main() {}

src/test/ui/type-alias-impl-trait/static-const-types.stderr

@@ -0,0 +1,33 @@
+error[E0308]: mismatched types
+  --> $DIR/static-const-types.rs:11:20
+   |
+LL | type Foo = impl Debug;
+   |            ---------- the expected opaque type
+...
+LL | static FOO1: Foo = 22_u32;
+   |                    ^^^^^^ expected opaque type, found `u32`
+   |
+   = note: expected opaque type `impl Debug`
+                     found type `u32`
+
+error[E0308]: mismatched types
+  --> $DIR/static-const-types.rs:13:19
+   |
+LL | type Foo = impl Debug;
+   |            ---------- the expected opaque type
+...
+LL | const FOO2: Foo = 22_u32;
+   |                   ^^^^^^ expected opaque type, found `u32`
+   |
+   = note: expected opaque type `impl Debug`
+                     found type `u32`
+
+error: could not find defining uses
+  --> $DIR/static-const-types.rs:8:12
+   |
+LL | type Foo = impl Debug;
+   |            ^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.