Merge commit '371120bdbf' into clippyup

tests/ui/default_constructed_unit_structs.fixed

@@ -0,0 +1,119 @@
+//@run-rustfix
+
+#![allow(unused)]
+#![warn(clippy::default_constructed_unit_structs)]
+use std::marker::PhantomData;
+
+#[derive(Default)]
+struct UnitStruct;
+
+impl UnitStruct {
+    fn new() -> Self {
+        //should lint
+        Self
+    }
+}
+
+#[derive(Default)]
+struct TupleStruct(usize);
+
+impl TupleStruct {
+    fn new() -> Self {
+        // should not lint
+        Self(Default::default())
+    }
+}
+
+// no lint for derived impl
+#[derive(Default)]
+struct NormalStruct {
+    inner: PhantomData<usize>,
+}
+
+struct NonDefaultStruct;
+
+impl NonDefaultStruct {
+    fn default() -> Self {
+        Self
+    }
+}
+
+#[derive(Default)]
+enum SomeEnum {
+    #[default]
+    Unit,
+    Tuple(UnitStruct),
+    Struct {
+        inner: usize,
+    },
+}
+
+impl NormalStruct {
+    fn new() -> Self {
+        // should lint
+        Self {
+            inner: PhantomData,
+        }
+    }
+
+    fn new2() -> Self {
+        // should not lint
+        Self {
+            inner: Default::default(),
+        }
+    }
+}
+
+#[derive(Default)]
+struct GenericStruct<T> {
+    t: T,
+}
+
+impl<T: Default> GenericStruct<T> {
+    fn new() -> Self {
+        // should not lint
+        Self { t: T::default() }
+    }
+
+    fn new2() -> Self {
+        // should not lint
+        Self { t: Default::default() }
+    }
+}
+
+struct FakeDefault;
+impl FakeDefault {
+    fn default() -> Self {
+        Self
+    }
+}
+
+impl Default for FakeDefault {
+    fn default() -> Self {
+        Self
+    }
+}
+
+#[derive(Default)]
+struct EmptyStruct {}
+
+#[derive(Default)]
+#[non_exhaustive]
+struct NonExhaustiveStruct;
+
+fn main() {
+    // should lint
+    let _ = PhantomData::<usize>;
+    let _: PhantomData<i32> = PhantomData;
+    let _ = UnitStruct;
+
+    // should not lint
+    let _ = TupleStruct::default();
+    let _ = NormalStruct::default();
+    let _ = NonExhaustiveStruct::default();
+    let _ = SomeEnum::default();
+    let _ = NonDefaultStruct::default();
+    let _ = EmptyStruct::default();
+    let _ = FakeDefault::default();
+    let _ = <FakeDefault as Default>::default();
+}