Code change:
#[doc(keyword = "struct")] // <del> /// The `struct` keyword. </del> <ins> /// The keyword used to define structs. </ins> /// <del> /// The `struct` keyword is used to define a struct type. </del> <ins> /// Structs in Rust come in three flavours: Regular structs, tuple structs, /// and empty structs. </ins> /// <del> /// Example: </del> <ins> /// ```rust /// struct Regular { ///     field1: f32, ///     field2: String, ///     pub field3: bool /// } /// /// struct Tuple(u32, String); </ins> /// <ins> /// struct Empty; </ins> /// ``` <del> /// struct Foo { ///     field1: u32, ///     field2: String, </del> <ins> /// /// Regular structs are the most commonly used. Each field defined within them has a name and a /// type, and once defined can be accessed using `example_struct.field` syntax. The fields of a /// struct share its mutability, so `foo.bar = 2;` would only be valid if `foo` was mutable. Adding /// `pub` to a field makes it visible to code in other modules, as well as allowing it to be /// directly accessed and modified. /// /// Tuple structs are similar to regular structs, but its fields have no names. They are used like /// tuples, with deconstruction possible via `let TupleStruct(x, y) = foo;` syntax.  For accessing /// individual variables, the same syntax is used as with regular tuples, namely `foo.0`, `foo.1`, /// etc, starting at zero. /// /// Empty structs, or unit-like structs, are most commonly used as markers, for example /// [`PhantomData`]. Empty structs have a size of zero bytes, but unlike empty enums they can be /// instantiated, making them similar to the unit type `()`. Unit-like structs are useful when you /// need to implement a trait on something, but don't need to store any data inside it. /// /// # Instantiation /// /// Structs can be instantiated in a manner of different ways, each of which can be mixed and /// matched as needed. The most common way to make a new struct is via a constructor method such as /// `new()`, but when that isn't available (or you're writing the constructor itself), struct /// literal syntax is used: /// /// ```rust /// # struct Foo { field1: f32, field2: String, etc: bool } /// let example = Foo { ///     field1: 42.0, ///     field2: "blah".to_string(), ///     etc: true, /// }; /// ``` /// /// It's only possible to directly instantiate a struct using struct literal syntax when all of its /// fields are visible to you. /// /// There are a handful of shortcuts provided to make writing constructors more convenient, most /// common of which is the Field Init shorthand. When there is a variable and a field of the same /// name, the assignment can be simplified from `field: field` into simply `field`. The following /// example of a hypothetical constructor demonstrates this: /// /// ```rust /// struct User { ///     name: String, ///     admin: bool, </ins> /// } <ins> /// /// impl User { ///     pub fn new(name: String) -> Self { ///         Self { ///             name, ///             admin: false, ///         } ///     } /// } /// ``` /// /// Another shortcut for struct instantiation is available, used when you need to make a new /// struct that has the same values as most of a previous struct of the same type, called struct /// update syntax: /// /// ```rust /// # struct Foo { field1: String, field2: () } /// # let thing = Foo { field1: "".to_string(), field2: () }; /// let updated_thing = Foo { ///     field1: "a new value".to_string(), ///     ..thing /// }; </ins> /// ``` /// <del> /// There are different kinds of structs. For more information, take a look at the /// [Rust Book][book]. </del> <ins> /// Tuple structs are instantiated in the same way as tuples themselves, except with the struct's /// name as a prefix: `Foo(123, false, 0.1)`. /// /// Empty structs are instantiated with just their name, and don't need anything else. `let thing = /// EmptyStruct;` /// /// # Style conventions /// /// Structs are always written in CamelCase, with few exceptions. While the trailing comma on a /// struct's list of fields can be omitted, it's usually kept for convenience in adding and /// removing fields down the line. /// /// For more information on structs, take a look at the [Rust Book][book] or the /// [Reference][reference]. </ins> /// <ins> /// [`PhantomData`]: marker/struct.PhantomData.html </ins> /// [book]: https://doc.rust-lang.org/book/second-edition/ch05-01-defining-structs.html <ins> /// [reference]: https://doc.rust-lang.org/reference/items/structs.html </ins> mod struct_keyword { }

Related discussion:
text: ARC is beginning to infect more and more types, and they each must have a clone method, but there is no trait to implement.
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Along with this, we should provide a default implementation of Clonable for all copyable types.
Closing this now that has been implemented. There are no doubt some types left that should have a implementation, but they can be dealt with on a case-by-case basis.