Add tests for #[rustc_default_body_unstable]

Author: WaffleLapkin

src/test/ui/stability-attribute/auxiliary/default_body.rs

@@ -0,0 +1,29 @@
+#![crate_type = "lib"]
+#![feature(staged_api, rustc_attrs)]
+#![stable(feature = "stable_feature", since = "1.0.0")]
+
+#[stable(feature = "stable_feature", since = "1.0.0")]
+pub trait JustTrait {
+    #[stable(feature = "stable_feature", since = "1.0.0")]
+    #[rustc_default_body_unstable(feature = "constant_default_body", issue = "none")]
+    const CONSTANT: usize = 0;
+
+    #[rustc_default_body_unstable(feature = "fun_default_body", issue = "none")]
+    #[stable(feature = "stable_feature", since = "1.0.0")]
+    fn fun() {}
+}
+
+#[rustc_must_implement_one_of(eq, neq)]
+#[stable(feature = "stable_feature", since = "1.0.0")]
+pub trait Equal {
+    #[rustc_default_body_unstable(feature = "eq_default_body", issue = "none")]
+    #[stable(feature = "stable_feature", since = "1.0.0")]
+    fn eq(&self, other: &Self) -> bool {
+        !self.neq(other)
+    }
+
+    #[stable(feature = "stable_feature", since = "1.0.0")]
+    fn neq(&self, other: &Self) -> bool {
+        !self.eq(other)
+    }
+}

src/test/ui/stability-attribute/default-body-stability-err.rs

@@ -0,0 +1,19 @@
+// aux-build:default_body.rs
+#![crate_type = "lib"]
+
+extern crate default_body;
+
+use default_body::{Equal, JustTrait};
+
+struct Type;
+
+impl JustTrait for Type {}
+//~^ ERROR use of unstable library feature 'fun_default_body'
+//~| ERROR use of unstable library feature 'constant_default_body'
+
+impl Equal for Type {
+    //~^ ERROR use of unstable library feature 'eq_default_body'
+    fn neq(&self, other: &Self) -> bool {
+        false
+    }
+}

src/test/ui/stability-attribute/default-body-stability-err.stderr

@@ -0,0 +1,32 @@
+error[E0658]: use of unstable library feature 'constant_default_body'
+  --> $DIR/default-body-stability-err.rs:10:1
+   |
+LL | impl JustTrait for Type {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(constant_default_body)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'fun_default_body'
+  --> $DIR/default-body-stability-err.rs:10:1
+   |
+LL | impl JustTrait for Type {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(fun_default_body)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'eq_default_body'
+  --> $DIR/default-body-stability-err.rs:14:1
+   |
+LL | / impl Equal for Type {
+LL | |
+LL | |     fn neq(&self, other: &Self) -> bool {
+LL | |         false
+LL | |     }
+LL | | }
+   | |_^
+   |
+   = help: add `#![feature(eq_default_body)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/stability-attribute/default-body-stability-ok-enables.rs

@@ -0,0 +1,18 @@
+// check-pass
+// aux-build:default_body.rs
+#![crate_type = "lib"]
+#![feature(fun_default_body, eq_default_body, constant_default_body)]
+
+extern crate default_body;
+
+use default_body::{Equal, JustTrait};
+
+struct Type;
+
+impl JustTrait for Type {}
+
+impl Equal for Type {
+    fn neq(&self, other: &Self) -> bool {
+        false
+    }
+}

src/test/ui/stability-attribute/default-body-stability-ok-impls.rs

@@ -0,0 +1,21 @@
+// check-pass
+// aux-build:default_body.rs
+#![crate_type = "lib"]
+
+extern crate default_body;
+
+use default_body::{Equal, JustTrait};
+
+struct Type;
+
+impl JustTrait for Type {
+    const CONSTANT: usize = 1;
+
+    fn fun() {}
+}
+
+impl Equal for Type {
+    fn eq(&self, other: &Self) -> bool {
+        false
+    }
+}