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+### What it does
+checks for `Box::new(T::default())`, which is better written as
+`Box::<T>::default()`.
+
+### Why is this bad?
+First, it's more complex, involving two calls instead of one.
+Second, `Box::default()` can be faster
+[in certain cases](https://nnethercote.github.io/perf-book/standard-library-types.html#box).
+
+### Known problems
+The lint may miss some cases (e.g. Box::new(String::from(""))).
+On the other hand, it will trigger on cases where the `default`
+code comes from a macro that does something different based on
+e.g. target operating system.
+
+### Example
+```
+let x: Box<String> = Box::new(Default::default());
+```
+Use instead:
+```
+let x: Box<String> = Box::default();
+```
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