Move CoerceUnsized to module.

Author: Clar Charr

src/libcore/ops/mod.rs

@@ -155,6 +155,7 @@ mod index;
 mod place;
 mod range;
 mod try;
+mod unsize;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::arith::{Add, Sub, Mul, Div, Rem, Neg};
@@ -190,7 +191,8 @@ pub use self::try::Try;
 #[unstable(feature = "placement_new_protocol", issue = "27779")]
 pub use self::place::{Place, Placer, InPlace, Boxed, BoxPlace};
 
-use marker::Unsize;
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+pub use self::unsize::CoerceUnsized;
 
 /// The `Drop` trait is used to run some code when a value goes out of scope.
 /// This is sometimes called a 'destructor'.
@@ -281,71 +283,3 @@ pub trait Drop {
     #[stable(feature = "rust1", since = "1.0.0")]
     fn drop(&mut self);
 }
-
-/// Trait that indicates that this is a pointer or a wrapper for one,
-/// where unsizing can be performed on the pointee.
-///
-/// See the [DST coercion RfC][dst-coerce] and [the nomicon entry on coercion][nomicon-coerce]
-/// for more details.
-///
-/// For builtin pointer types, pointers to `T` will coerce to pointers to `U` if `T: Unsize<U>`
-/// by converting from a thin pointer to a fat pointer.
-///
-/// For custom types, the coercion here works by coercing `Foo<T>` to `Foo<U>`
-/// provided an impl of `CoerceUnsized<Foo<U>> for Foo<T>` exists.
-/// Such an impl can only be written if `Foo<T>` has only a single non-phantomdata
-/// field involving `T`. If the type of that field is `Bar<T>`, an implementation
-/// of `CoerceUnsized<Bar<U>> for Bar<T>` must exist. The coercion will work by
-/// by coercing the `Bar<T>` field into `Bar<U>` and filling in the rest of the fields
-/// from `Foo<T>` to create a `Foo<U>`. This will effectively drill down to a pointer
-/// field and coerce that.
-///
-/// Generally, for smart pointers you will implement
-/// `CoerceUnsized<Ptr<U>> for Ptr<T> where T: Unsize<U>, U: ?Sized`, with an
-/// optional `?Sized` bound on `T` itself. For wrapper types that directly embed `T`
-/// like `Cell<T>` and `RefCell<T>`, you
-/// can directly implement `CoerceUnsized<Wrap<U>> for Wrap<T> where T: CoerceUnsized<U>`.
-/// This will let coercions of types like `Cell<Box<T>>` work.
-///
-/// [`Unsize`][unsize] is used to mark types which can be coerced to DSTs if behind
-/// pointers. It is implemented automatically by the compiler.
-///
-/// [dst-coerce]: https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md
-/// [unsize]: ../marker/trait.Unsize.html
-/// [nomicon-coerce]: ../../nomicon/coercions.html
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-#[lang="coerce_unsized"]
-pub trait CoerceUnsized<T> {
-    // Empty.
-}
-
-// &mut T -> &mut U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
-// &mut T -> &U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<'a, 'b: 'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b mut T {}
-// &mut T -> *mut U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for &'a mut T {}
-// &mut T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a mut T {}
-
-// &T -> &U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<'a, 'b: 'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
-// &T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a T {}
-
-// *mut T -> *mut U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
-// *mut T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
-
-// *const T -> *const U
-#[unstable(feature = "coerce_unsized", issue = "27732")]
-impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}

src/libcore/ops/unsize.rs

@@ -0,0 +1,79 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use marker::Unsize;
+
+/// Trait that indicates that this is a pointer or a wrapper for one,
+/// where unsizing can be performed on the pointee.
+///
+/// See the [DST coercion RfC][dst-coerce] and [the nomicon entry on coercion][nomicon-coerce]
+/// for more details.
+///
+/// For builtin pointer types, pointers to `T` will coerce to pointers to `U` if `T: Unsize<U>`
+/// by converting from a thin pointer to a fat pointer.
+///
+/// For custom types, the coercion here works by coercing `Foo<T>` to `Foo<U>`
+/// provided an impl of `CoerceUnsized<Foo<U>> for Foo<T>` exists.
+/// Such an impl can only be written if `Foo<T>` has only a single non-phantomdata
+/// field involving `T`. If the type of that field is `Bar<T>`, an implementation
+/// of `CoerceUnsized<Bar<U>> for Bar<T>` must exist. The coercion will work by
+/// by coercing the `Bar<T>` field into `Bar<U>` and filling in the rest of the fields
+/// from `Foo<T>` to create a `Foo<U>`. This will effectively drill down to a pointer
+/// field and coerce that.
+///
+/// Generally, for smart pointers you will implement
+/// `CoerceUnsized<Ptr<U>> for Ptr<T> where T: Unsize<U>, U: ?Sized`, with an
+/// optional `?Sized` bound on `T` itself. For wrapper types that directly embed `T`
+/// like `Cell<T>` and `RefCell<T>`, you
+/// can directly implement `CoerceUnsized<Wrap<U>> for Wrap<T> where T: CoerceUnsized<U>`.
+/// This will let coercions of types like `Cell<Box<T>>` work.
+///
+/// [`Unsize`][unsize] is used to mark types which can be coerced to DSTs if behind
+/// pointers. It is implemented automatically by the compiler.
+///
+/// [dst-coerce]: https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md
+/// [unsize]: ../marker/trait.Unsize.html
+/// [nomicon-coerce]: ../../nomicon/coercions.html
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+#[lang="coerce_unsized"]
+pub trait CoerceUnsized<T> {
+    // Empty.
+}
+
+// &mut T -> &mut U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
+// &mut T -> &U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<'a, 'b: 'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b mut T {}
+// &mut T -> *mut U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for &'a mut T {}
+// &mut T -> *const U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a mut T {}
+
+// &T -> &U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<'a, 'b: 'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
+// &T -> *const U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a T {}
+
+// *mut T -> *mut U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
+// *mut T -> *const U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
+
+// *const T -> *const U
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}