Added tests for feature.

src/test/run-pass/type-alias-enum-variants.rs

@@ -0,0 +1,30 @@
+#![feature(type_alias_enum_variants)]
+
+#[derive(Debug, PartialEq, Eq)]
+enum Foo {
+    Bar(i32),
+    Baz { i: i32 },
+}
+
+type FooAlias = Foo;
+type OptionAlias = Option<i32>;
+
+impl Foo {
+    fn foo() -> Self {
+        Self::Bar(3)
+    }
+}
+
+fn main() {
+    let t = FooAlias::Bar(1);
+    assert_eq!(t, Foo::Bar(1));
+    let t = FooAlias::Baz { i: 2 };
+    assert_eq!(t, Foo::Baz { i: 2 });
+    match t {
+        FooAlias::Bar(_i) => {}
+        FooAlias::Baz { i } => { assert_eq!(i, 2); }
+    }
+    assert_eq!(Foo::foo(), Foo::Bar(3));
+
+    assert_eq!(OptionAlias::Some(4), Option::Some(4));
+}

src/test/ui/feature-gates/feature-gate-type_alias_enum_variants.rs

@@ -0,0 +1,25 @@
+// 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.
+
+enum Foo {
+    Bar(i32),
+    Baz { i: i32 },
+}
+
+type Alias = Foo;
+
+fn main() {
+    let t = Alias::Bar(0);
+    let t = Alias::Baz { i: 0 };
+    match t {
+        Alias::Bar(_i) => {}
+        Alias::Baz { i: _i } => {}
+    }
+}

src/test/ui/feature-gates/feature-gate-type_alias_enum_variants.stderr

@@ -0,0 +1,72 @@
+error: type alias enum variants are not yet allowed
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:19:13
+   |
+LL |     let t = Alias::Bar(0);
+   |             ^^^^^^^^^^
+   |
+   = help: add `#![feature(type_alias_enum_variants)]` to the crate attributes to enable
+
+error[E0599]: no variant named `Bar` found for type `Foo` in the current scope
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:19:20
+   |
+LL | enum Foo {
+   | -------- variant `Bar` not found here
+...
+LL |     let t = Alias::Bar(0);
+   |             -------^^^
+   |             |
+   |             variant not found in `Foo`
+   |
+   = help: did you mean `Bar`?
+
+error: type alias enum variants are not yet allowed
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:20:13
+   |
+LL |     let t = Alias::Baz { i: 0 };
+   |             ^^^^^^^^^^
+   |
+   = help: add `#![feature(type_alias_enum_variants)]` to the crate attributes to enable
+
+error[E0223]: ambiguous associated type
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:20:13
+   |
+LL |     let t = Alias::Baz { i: 0 };
+   |             ^^^^^^^^^^ help: use fully-qualified syntax: `<Foo as Trait>::Baz`
+
+error: type alias enum variants are not yet allowed
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:22:9
+   |
+LL |         Alias::Bar(_i) => {}
+   |         ^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(type_alias_enum_variants)]` to the crate attributes to enable
+
+error[E0599]: no variant named `Bar` found for type `Foo` in the current scope
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:22:16
+   |
+LL | enum Foo {
+   | -------- variant `Bar` not found here
+...
+LL |         Alias::Bar(_i) => {}
+   |         -------^^^---- variant not found in `Foo`
+   |
+   = help: did you mean `Bar`?
+
+error: type alias enum variants are not yet allowed
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:23:9
+   |
+LL |         Alias::Baz { i: _i } => {}
+   |         ^^^^^^^^^^
+   |
+   = help: add `#![feature(type_alias_enum_variants)]` to the crate attributes to enable
+
+error[E0223]: ambiguous associated type
+  --> $DIR/feature-gate-type_alias_enum_variants.rs:23:9
+   |
+LL |         Alias::Baz { i: _i } => {}
+   |         ^^^^^^^^^^ help: use fully-qualified syntax: `<Foo as Trait>::Baz`
+
+error: aborting due to 8 previous errors
+
+Some errors occurred: E0223, E0599.
+For more information about an error, try `rustc --explain E0223`.

src/test/ui/type-alias-enum-variants.rs

@@ -0,0 +1,10 @@
+#![feature(type_alias_enum_variants)]
+
+type Alias<T> = Option<T>;
+
+fn main() {
+    let _ = Option::<u8>::None; // OK
+    let _ = Option::None::<u8>; // OK (Lint in future!)
+    let _ = Alias::<u8>::None; // OK
+    let _ = Alias::None::<u8>; // Error
+}

src/test/ui/type-alias-enum-variants.stderr

@@ -0,0 +1,9 @@
+error[E0109]: type parameters are not allowed on this type
+  --> $DIR/type-alias-enum-variants.rs:9:27
+   |
+LL |     let _ = Alias::None::<u8>; // Error
+   |                           ^^ type parameter not allowed
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0109`.