add rustfix annotation

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();
+}

tests/ui/default_constructed_unit_structs.rs

@@ -1,3 +1,5 @@
+//@run-rustfix
+
 #![allow(unused)]
 #![warn(clippy::default_constructed_unit_structs)]
 use std::marker::PhantomData;

tests/ui/default_constructed_unit_structs.stderr

@@ -1,5 +1,5 @@
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:11:13
+  --> $DIR/default_constructed_unit_structs.rs:13:13
    |
 LL |         Self::default()
    |             ^^^^^^^^^^^ help: remove this call to `default`
@@ -7,25 +7,25 @@ LL |         Self::default()
    = note: `-D clippy::default-constructed-unit-structs` implied by `-D warnings`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:53:31
+  --> $DIR/default_constructed_unit_structs.rs:55:31
    |
 LL |             inner: PhantomData::default(),
    |                               ^^^^^^^^^^^ help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:104:33
+  --> $DIR/default_constructed_unit_structs.rs:106:33
    |
 LL |     let _ = PhantomData::<usize>::default();
    |                                 ^^^^^^^^^^^ help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:105:42
+  --> $DIR/default_constructed_unit_structs.rs:107:42
    |
 LL |     let _: PhantomData<i32> = PhantomData::default();
    |                                          ^^^^^^^^^^^ help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:106:23
+  --> $DIR/default_constructed_unit_structs.rs:108:23
    |
 LL |     let _ = UnitStruct::default();
    |                       ^^^^^^^^^^^ help: remove this call to `default`