Add struct to stability ui tests in usefulness

Author: DevinR528

src/test/ui/pattern/usefulness/auxiliary/unstable.rs

@@ -2,11 +2,22 @@
 #![stable(feature = "stable_test_feature", since = "1.0.0")]
 
 #[stable(feature = "stable_test_feature", since = "1.0.0")]
-pub enum Foo {
+pub enum UnstableEnum {
     #[stable(feature = "stable_test_feature", since = "1.0.0")]
     Stable,
     #[stable(feature = "stable_test_feature", since = "1.0.0")]
     Stable2,
     #[unstable(feature = "unstable_test_feature", issue = "none")]
     Unstable,
 }
+
+#[derive(Default)]
+#[stable(feature = "stable_test_feature", since = "1.0.0")]
+pub struct UnstableStruct {
+    #[stable(feature = "stable_test_feature", since = "1.0.0")]
+    pub stable: bool,
+    #[stable(feature = "stable_test_feature", since = "1.0.0")]
+    pub stable2: usize,
+    #[unstable(feature = "unstable_test_feature", issue = "none")]
+    pub unstable: u8,
+}

src/test/ui/pattern/usefulness/stable-gated-fields.rs

@@ -0,0 +1,16 @@
+// aux-build:unstable.rs
+
+extern crate unstable;
+
+use unstable::UnstableStruct;
+
+fn main() {
+    let UnstableStruct { stable } = UnstableStruct::default();
+    //~^ pattern does not mention field `stable2` and inaccessible fields
+
+    let UnstableStruct { stable, stable2 } = UnstableStruct::default();
+    //~^ pattern requires `..` due to inaccessible fields
+
+    // OK: stable field is matched
+    let UnstableStruct { stable, stable2, .. } = UnstableStruct::default();
+}

src/test/ui/pattern/usefulness/stable-gated-patterns.rs

@@ -2,17 +2,17 @@
 
 extern crate unstable;
 
-use unstable::Foo;
+use unstable::UnstableEnum;
 
 fn main() {
-    match Foo::Stable {
-        Foo::Stable => {}
+    match UnstableEnum::Stable {
+        UnstableEnum::Stable => {}
     }
     //~^^^ non-exhaustive patterns: `Stable2` and `_` not covered
 
-    match Foo::Stable {
-        Foo::Stable => {}
-        Foo::Stable2 => {}
+    match UnstableEnum::Stable {
+        UnstableEnum::Stable => {}
+        UnstableEnum::Stable2 => {}
     }
     //~^^^^ non-exhaustive patterns: `_` not covered
 }

src/test/ui/pattern/usefulness/unstable-gated-fields.rs

@@ -0,0 +1,18 @@
+#![feature(unstable_test_feature)]
+
+// aux-build:unstable.rs
+
+extern crate unstable;
+
+use unstable::UnstableStruct;
+
+fn main() {
+    let UnstableStruct { stable, stable2, } = UnstableStruct::default();
+    //~^ pattern does not mention field `unstable`
+
+    let UnstableStruct { stable, unstable, } = UnstableStruct::default();
+    //~^ pattern does not mention field `stable2`
+
+    // OK: stable field is matched
+    let UnstableStruct { stable, stable2, unstable } = UnstableStruct::default();
+}

src/test/ui/pattern/usefulness/unstable-gated-patterns.rs

@@ -4,19 +4,19 @@
 
 extern crate unstable;
 
-use unstable::Foo;
+use unstable::UnstableEnum;
 
 fn main() {
-    match Foo::Stable {
-        Foo::Stable => {}
-        Foo::Stable2 => {}
+    match UnstableEnum::Stable {
+        UnstableEnum::Stable => {}
+        UnstableEnum::Stable2 => {}
     }
     //~^^^^ non-exhaustive patterns: `Unstable` not covered
 
     // Ok: all variants are explicitly matched
-    match Foo::Stable {
-        Foo::Stable => {}
-        Foo::Stable2 => {}
-        Foo::Unstable => {}
+    match UnstableEnum::Stable {
+        UnstableEnum::Stable => {}
+        UnstableEnum::Stable2 => {}
+        UnstableEnum::Unstable => {}
     }
 }