src/libcore/any.rs - third_party/rust - Git at Google

 //! This module implements the `Any` trait, which enables dynamic typing
 //! of any `'static` type through runtime reflection.
 //!
 //! `Any` itself can be used to get a `TypeId`, and has more features when used
 //! as a trait object. As `&dyn Any` (a borrowed trait object), it has the `is`
 //! and `downcast_ref` methods, to test if the contained value is of a given type,
 //! and to get a reference to the inner value as a type. As `&mut dyn Any`, there
 //! is also the `downcast_mut` method, for getting a mutable reference to the
 //! inner value. `Box<dyn Any>` adds the `downcast` method, which attempts to
 //! convert to a `Box<T>`. See the [`Box`] documentation for the full details.
 //!
 //! Note that `&dyn Any` is limited to testing whether a value is of a specified
 //! concrete type, and cannot be used to test whether a type implements a trait.
 //!
 //! [`Box`]: ../../std/boxed/struct.Box.html
 //!
 //! # Examples
 //!
 //! Consider a situation where we want to log out a value passed to a function.
 //! We know the value we're working on implements Debug, but we don't know its
 //! concrete type. We want to give special treatment to certain types: in this
 //! case printing out the length of String values prior to their value.
 //! We don't know the concrete type of our value at compile time, so we need to
 //! use runtime reflection instead.
 //!
 //! ```rust
 //! use std::fmt::Debug;
 //! use std::any::Any;
 //!
 //! // Logger function for any type that implements Debug.
 //! fn log<T: Any + Debug>(value: &T) {
 //!     let value_any = value as &dyn Any;
 //!
 //!     // Try to convert our value to a `String`. If successful, we want to
 //!     // output the String`'s length as well as its value. If not, it's a
 //!     // different type: just print it out unadorned.
 //!     match value_any.downcast_ref::<String>() {
 //!         Some(as_string) => {
 //!             println!("String ({}): {}", as_string.len(), as_string);
 //!         }
 //!         None => {
 //!             println!("{:?}", value);
 //!         }
 //!     }
 //! }
 //!
 //! // This function wants to log its parameter out prior to doing work with it.
 //! fn do_work<T: Any + Debug>(value: &T) {
 //!     log(value);
 //!     // ...do some other work
 //! }
 //!
 //! fn main() {
 //!     let my_string = "Hello World".to_string();
 //!     do_work(&my_string);
 //!
 //!     let my_i8: i8 = 100;
 //!     do_work(&my_i8);
 //! }
 //! ```

 #![stable(feature = "rust1", since = "1.0.0")]

 use crate::fmt;
 use crate::intrinsics;

 ///////////////////////////////////////////////////////////////////////////////
 // Any trait
 ///////////////////////////////////////////////////////////////////////////////

 /// A trait to emulate dynamic typing.
 ///
 /// Most types implement `Any`. However, any type which contains a non-`'static` reference does not.
 /// See the [module-level documentation][mod] for more details.
 ///
 /// [mod]: index.html
 // This trait is not unsafe, though we rely on the specifics of it's sole impl's
 // `type_id` function in unsafe code (e.g., `downcast`). Normally, that would be
 // a problem, but because the only impl of `Any` is a blanket implementation, no
 // other code can implement `Any`.
 //
 // We could plausibly make this trait unsafe -- it would not cause breakage,
 // since we control all the implementations -- but we choose not to as that's
 // both not really necessary and may confuse users about the distinction of
 // unsafe traits and unsafe methods (i.e., `type_id` would still be safe to call,
 // but we would likely want to indicate as such in documentation).
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Any: 'static {
     /// Gets the `TypeId` of `self`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::{Any, TypeId};
     ///
     /// fn is_string(s: &dyn Any) -> bool {
     ///     TypeId::of::<String>() == s.type_id()
     /// }
     ///
     /// assert_eq!(is_string(&0), false);
     /// assert_eq!(is_string(&"cookie monster".to_string()), true);
     /// ```
     #[stable(feature = "get_type_id", since = "1.34.0")]
     fn type_id(&self) -> TypeId;
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: 'static + ?Sized> Any for T {
     fn type_id(&self) -> TypeId {
         TypeId::of::<T>()
     }
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Extension methods for Any trait objects.
 ///////////////////////////////////////////////////////////////////////////////

 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for dyn Any {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.pad("Any")
     }
 }

 // Ensure that the result of e.g., joining a thread can be printed and
 // hence used with `unwrap`. May eventually no longer be needed if
 // dispatch works with upcasting.
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Debug for dyn Any + Send {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.pad("Any")
     }
 }

 #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
 impl fmt::Debug for dyn Any + Send + Sync {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.pad("Any")
     }
 }

 impl dyn Any {
     /// Returns `true` if the boxed type is the same as `T`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn is_string(s: &dyn Any) {
     ///     if s.is::<String>() {
     ///         println!("It's a string!");
     ///     } else {
     ///         println!("Not a string...");
     ///     }
     /// }
     ///
     /// is_string(&0);
     /// is_string(&"cookie monster".to_string());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is<T: Any>(&self) -> bool {
         // Get `TypeId` of the type this function is instantiated with.
         let t = TypeId::of::<T>();

         // Get `TypeId` of the type in the trait object.
         let concrete = self.type_id();

         // Compare both `TypeId`s on equality.
         t == concrete
     }

     /// Returns some reference to the boxed value if it is of type `T`, or
     /// `None` if it isn't.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn print_if_string(s: &dyn Any) {
     ///     if let Some(string) = s.downcast_ref::<String>() {
     ///         println!("It's a string({}): '{}'", string.len(), string);
     ///     } else {
     ///         println!("Not a string...");
     ///     }
     /// }
     ///
     /// print_if_string(&0);
     /// print_if_string(&"cookie monster".to_string());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
         if self.is::<T>() {
             // SAFETY: just checked whether we are pointing to the correct type
             unsafe { Some(&*(self as *const dyn Any as *const T)) }
         } else {
             None
         }
     }

     /// Returns some mutable reference to the boxed value if it is of type `T`, or
     /// `None` if it isn't.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn modify_if_u32(s: &mut dyn Any) {
     ///     if let Some(num) = s.downcast_mut::<u32>() {
     ///         *num = 42;
     ///     }
     /// }
     ///
     /// let mut x = 10u32;
     /// let mut s = "starlord".to_string();
     ///
     /// modify_if_u32(&mut x);
     /// modify_if_u32(&mut s);
     ///
     /// assert_eq!(x, 42);
     /// assert_eq!(&s, "starlord");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
         if self.is::<T>() {
             // SAFETY: just checked whether we are pointing to the correct type
             unsafe { Some(&mut *(self as *mut dyn Any as *mut T)) }
         } else {
             None
         }
     }
 }

 impl dyn Any + Send {
     /// Forwards to the method defined on the type `Any`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn is_string(s: &(dyn Any + Send)) {
     ///     if s.is::<String>() {
     ///         println!("It's a string!");
     ///     } else {
     ///         println!("Not a string...");
     ///     }
     /// }
     ///
     /// is_string(&0);
     /// is_string(&"cookie monster".to_string());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn is<T: Any>(&self) -> bool {
         Any::is::<T>(self)
     }

     /// Forwards to the method defined on the type `Any`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn print_if_string(s: &(dyn Any + Send)) {
     ///     if let Some(string) = s.downcast_ref::<String>() {
     ///         println!("It's a string({}): '{}'", string.len(), string);
     ///     } else {
     ///         println!("Not a string...");
     ///     }
     /// }
     ///
     /// print_if_string(&0);
     /// print_if_string(&"cookie monster".to_string());
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
         Any::downcast_ref::<T>(self)
     }

     /// Forwards to the method defined on the type `Any`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn modify_if_u32(s: &mut (dyn Any + Send)) {
     ///     if let Some(num) = s.downcast_mut::<u32>() {
     ///         *num = 42;
     ///     }
     /// }
     ///
     /// let mut x = 10u32;
     /// let mut s = "starlord".to_string();
     ///
     /// modify_if_u32(&mut x);
     /// modify_if_u32(&mut s);
     ///
     /// assert_eq!(x, 42);
     /// assert_eq!(&s, "starlord");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
         Any::downcast_mut::<T>(self)
     }
 }

 impl dyn Any + Send + Sync {
     /// Forwards to the method defined on the type `Any`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn is_string(s: &(dyn Any + Send + Sync)) {
     ///     if s.is::<String>() {
     ///         println!("It's a string!");
     ///     } else {
     ///         println!("Not a string...");
     ///     }
     /// }
     ///
     /// is_string(&0);
     /// is_string(&"cookie monster".to_string());
     /// ```
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
     pub fn is<T: Any>(&self) -> bool {
         Any::is::<T>(self)
     }

     /// Forwards to the method defined on the type `Any`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn print_if_string(s: &(dyn Any + Send + Sync)) {
     ///     if let Some(string) = s.downcast_ref::<String>() {
     ///         println!("It's a string({}): '{}'", string.len(), string);
     ///     } else {
     ///         println!("Not a string...");
     ///     }
     /// }
     ///
     /// print_if_string(&0);
     /// print_if_string(&"cookie monster".to_string());
     /// ```
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
     pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
         Any::downcast_ref::<T>(self)
     }

     /// Forwards to the method defined on the type `Any`.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::Any;
     ///
     /// fn modify_if_u32(s: &mut (dyn Any + Send + Sync)) {
     ///     if let Some(num) = s.downcast_mut::<u32>() {
     ///         *num = 42;
     ///     }
     /// }
     ///
     /// let mut x = 10u32;
     /// let mut s = "starlord".to_string();
     ///
     /// modify_if_u32(&mut x);
     /// modify_if_u32(&mut s);
     ///
     /// assert_eq!(x, 42);
     /// assert_eq!(&s, "starlord");
     /// ```
     #[stable(feature = "any_send_sync_methods", since = "1.28.0")]
     #[inline]
     pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
         Any::downcast_mut::<T>(self)
     }
 }

 ///////////////////////////////////////////////////////////////////////////////
 // TypeID and its methods
 ///////////////////////////////////////////////////////////////////////////////

 /// A `TypeId` represents a globally unique identifier for a type.
 ///
 /// Each `TypeId` is an opaque object which does not allow inspection of what's
 /// inside but does allow basic operations such as cloning, comparison,
 /// printing, and showing.
 ///
 /// A `TypeId` is currently only available for types which ascribe to `'static`,
 /// but this limitation may be removed in the future.
 ///
 /// While `TypeId` implements `Hash`, `PartialOrd`, and `Ord`, it is worth
 /// noting that the hashes and ordering will vary between Rust releases. Beware
 /// of relying on them inside of your code!
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct TypeId {
     t: u64,
 }

 impl TypeId {
     /// Returns the `TypeId` of the type this generic function has been
     /// instantiated with.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::any::{Any, TypeId};
     ///
     /// fn is_string<T: ?Sized + Any>(_s: &T) -> bool {
     ///     TypeId::of::<String>() == TypeId::of::<T>()
     /// }
     ///
     /// assert_eq!(is_string(&0), false);
     /// assert_eq!(is_string(&"cookie monster".to_string()), true);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_const_unstable(feature = "const_type_id", issue = "41875")]
     pub const fn of<T: ?Sized + 'static>() -> TypeId {
         TypeId { t: intrinsics::type_id::<T>() }
     }
 }

 /// Returns the name of a type as a string slice.
 ///
 /// # Note
 ///
 /// This is intended for diagnostic use. The exact contents and format of the
 /// string are not specified, other than being a best-effort description of the
 /// type. For example, `type_name::<Option<String>>()` could return the
 /// `"Option<String>"` or `"std::option::Option<std::string::String>"`, but not
 /// `"foobar"`. In addition, the output may change between versions of the
 /// compiler.
 ///
 /// The type name should not be considered a unique identifier of a type;
 /// multiple types may share the same type name.
 ///
 /// The current implementation uses the same infrastructure as compiler
 /// diagnostics and debuginfo, but this is not guaranteed.
 ///
 /// # Examples
 ///
 /// ```rust
 /// assert_eq!(
 ///     std::any::type_name::<Option<String>>(),
 ///     "core::option::Option<alloc::string::String>",
 /// );
 /// ```
 #[stable(feature = "type_name", since = "1.38.0")]
 #[rustc_const_unstable(feature = "const_type_name", issue = "63084")]
 pub const fn type_name<T: ?Sized>() -> &'static str {
     intrinsics::type_name::<T>()
 }

 /// Returns the name of the type of the pointed-to value as a string slice.
 /// This is the same as `type_name::<T>()`, but can be used where the type of a
 /// variable is not easily available.
 ///
 /// # Note
 ///
 /// This is intended for diagnostic use. The exact contents and format of the
 /// string are not specified, other than being a best-effort description of the
 /// type. For example, `type_name_of::<Option<String>>(None)` could return
 /// `"Option<String>"` or `"std::option::Option<std::string::String>"`, but not
 /// `"foobar"`. In addition, the output may change between versions of the
 /// compiler.
 ///
 /// The type name should not be considered a unique identifier of a type;
 /// multiple types may share the same type name.
 ///
 /// The current implementation uses the same infrastructure as compiler
 /// diagnostics and debuginfo, but this is not guaranteed.
 ///
 /// # Examples
 ///
 /// Prints the default integer and float types.
 ///
 /// ```rust
 /// #![feature(type_name_of_val)]
 /// use std::any::type_name_of_val;
 ///
 /// let x = 1;
 /// println!("{}", type_name_of_val(&x));
 /// let y = 1.0;
 /// println!("{}", type_name_of_val(&y));
 /// ```
 #[unstable(feature = "type_name_of_val", issue = "66359")]
 #[rustc_const_unstable(feature = "const_type_name", issue = "63084")]
 pub const fn type_name_of_val<T: ?Sized>(_val: &T) -> &'static str {
     type_name::<T>()
 }
	//! This module implements the `Any` trait, which enables dynamic typing
	//! of any `'static` type through runtime reflection.
	//!
	//! `Any` itself can be used to get a `TypeId`, and has more features when used
	//! as a trait object. As `&dyn Any` (a borrowed trait object), it has the `is`
	//! and `downcast_ref` methods, to test if the contained value is of a given type,
	//! and to get a reference to the inner value as a type. As `&mut dyn Any`, there
	//! is also the `downcast_mut` method, for getting a mutable reference to the
	//! inner value. `Box<dyn Any>` adds the `downcast` method, which attempts to
	//! convert to a `Box<T>`. See the [`Box`] documentation for the full details.
	//!
	//! Note that `&dyn Any` is limited to testing whether a value is of a specified
	//! concrete type, and cannot be used to test whether a type implements a trait.
	//!
	//! [`Box`]: ../../std/boxed/struct.Box.html
	//!
	//! # Examples
	//!
	//! Consider a situation where we want to log out a value passed to a function.
	//! We know the value we're working on implements Debug, but we don't know its
	//! concrete type. We want to give special treatment to certain types: in this
	//! case printing out the length of String values prior to their value.
	//! We don't know the concrete type of our value at compile time, so we need to
	//! use runtime reflection instead.
	//!
	//! ```rust
	//! use std::fmt::Debug;
	//! use std::any::Any;
	//!
	//! // Logger function for any type that implements Debug.
	//! fn log<T: Any + Debug>(value: &T) {
	//! let value_any = value as &dyn Any;
	//!
	//! // Try to convert our value to a `String`. If successful, we want to
	//! // output the String`'s length as well as its value. If not, it's a
	//! // different type: just print it out unadorned.
	//! match value_any.downcast_ref::<String>() {
	//! Some(as_string) => {
	//! println!("String ({}): {}", as_string.len(), as_string);
	//! }
	//! None => {
	//! println!("{:?}", value);
	//! }
	//! }
	//! }
	//!
	//! // This function wants to log its parameter out prior to doing work with it.
	//! fn do_work<T: Any + Debug>(value: &T) {
	//! log(value);
	//! // ...do some other work
	//! }
	//!
	//! fn main() {
	//! let my_string = "Hello World".to_string();
	//! do_work(&my_string);
	//!
	//! let my_i8: i8 = 100;
	//! do_work(&my_i8);
	//! }
	//! ```

	#![stable(feature = "rust1", since = "1.0.0")]

	use crate::fmt;
	use crate::intrinsics;

	///////////////////////////////////////////////////////////////////////////////
	// Any trait
	///////////////////////////////////////////////////////////////////////////////

	/// A trait to emulate dynamic typing.
	///
	/// Most types implement `Any`. However, any type which contains a non-`'static` reference does not.
	/// See the [module-level documentation][mod] for more details.
	///
	/// [mod]: index.html
	// This trait is not unsafe, though we rely on the specifics of it's sole impl's
	// `type_id` function in unsafe code (e.g., `downcast`). Normally, that would be
	// a problem, but because the only impl of `Any` is a blanket implementation, no
	// other code can implement `Any`.
	//
	// We could plausibly make this trait unsafe -- it would not cause breakage,
	// since we control all the implementations -- but we choose not to as that's
	// both not really necessary and may confuse users about the distinction of
	// unsafe traits and unsafe methods (i.e., `type_id` would still be safe to call,
	// but we would likely want to indicate as such in documentation).
	#[stable(feature = "rust1", since = "1.0.0")]
	pub trait Any: 'static {
	/// Gets the `TypeId` of `self`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::{Any, TypeId};
	///
	/// fn is_string(s: &dyn Any) -> bool {
	/// TypeId::of::<String>() == s.type_id()
	/// }
	///
	/// assert_eq!(is_string(&0), false);
	/// assert_eq!(is_string(&"cookie monster".to_string()), true);
	/// ```
	#[stable(feature = "get_type_id", since = "1.34.0")]
	fn type_id(&self) -> TypeId;
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl<T: 'static + ?Sized> Any for T {
	fn type_id(&self) -> TypeId {
	TypeId::of::<T>()
	}
	}

	///////////////////////////////////////////////////////////////////////////////
	// Extension methods for Any trait objects.
	///////////////////////////////////////////////////////////////////////////////

	#[stable(feature = "rust1", since = "1.0.0")]
	impl fmt::Debug for dyn Any {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	f.pad("Any")
	}
	}

	// Ensure that the result of e.g., joining a thread can be printed and
	// hence used with `unwrap`. May eventually no longer be needed if
	// dispatch works with upcasting.
	#[stable(feature = "rust1", since = "1.0.0")]
	impl fmt::Debug for dyn Any + Send {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	f.pad("Any")
	}
	}

	#[stable(feature = "any_send_sync_methods", since = "1.28.0")]
	impl fmt::Debug for dyn Any + Send + Sync {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
	f.pad("Any")
	}
	}

	impl dyn Any {
	/// Returns `true` if the boxed type is the same as `T`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn is_string(s: &dyn Any) {
	/// if s.is::<String>() {
	/// println!("It's a string!");
	/// } else {
	/// println!("Not a string...");
	/// }
	/// }
	///
	/// is_string(&0);
	/// is_string(&"cookie monster".to_string());
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn is<T: Any>(&self) -> bool {
	// Get `TypeId` of the type this function is instantiated with.
	let t = TypeId::of::<T>();

	// Get `TypeId` of the type in the trait object.
	let concrete = self.type_id();

	// Compare both `TypeId`s on equality.
	t == concrete
	}

	/// Returns some reference to the boxed value if it is of type `T`, or
	/// `None` if it isn't.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn print_if_string(s: &dyn Any) {
	/// if let Some(string) = s.downcast_ref::<String>() {
	/// println!("It's a string({}): '{}'", string.len(), string);
	/// } else {
	/// println!("Not a string...");
	/// }
	/// }
	///
	/// print_if_string(&0);
	/// print_if_string(&"cookie monster".to_string());
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
	if self.is::<T>() {
	// SAFETY: just checked whether we are pointing to the correct type
	unsafe { Some(&(self as const dyn Any as *const T)) }
	} else {
	None
	}
	}

	/// Returns some mutable reference to the boxed value if it is of type `T`, or
	/// `None` if it isn't.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn modify_if_u32(s: &mut dyn Any) {
	/// if let Some(num) = s.downcast_mut::<u32>() {
	/// *num = 42;
	/// }
	/// }
	///
	/// let mut x = 10u32;
	/// let mut s = "starlord".to_string();
	///
	/// modify_if_u32(&mut x);
	/// modify_if_u32(&mut s);
	///
	/// assert_eq!(x, 42);
	/// assert_eq!(&s, "starlord");
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
	if self.is::<T>() {
	// SAFETY: just checked whether we are pointing to the correct type
	unsafe { Some(&mut (self as mut dyn Any as *mut T)) }
	} else {
	None
	}
	}
	}

	impl dyn Any + Send {
	/// Forwards to the method defined on the type `Any`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn is_string(s: &(dyn Any + Send)) {
	/// if s.is::<String>() {
	/// println!("It's a string!");
	/// } else {
	/// println!("Not a string...");
	/// }
	/// }
	///
	/// is_string(&0);
	/// is_string(&"cookie monster".to_string());
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn is<T: Any>(&self) -> bool {
	Any::is::<T>(self)
	}

	/// Forwards to the method defined on the type `Any`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn print_if_string(s: &(dyn Any + Send)) {
	/// if let Some(string) = s.downcast_ref::<String>() {
	/// println!("It's a string({}): '{}'", string.len(), string);
	/// } else {
	/// println!("Not a string...");
	/// }
	/// }
	///
	/// print_if_string(&0);
	/// print_if_string(&"cookie monster".to_string());
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
	Any::downcast_ref::<T>(self)
	}

	/// Forwards to the method defined on the type `Any`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn modify_if_u32(s: &mut (dyn Any + Send)) {
	/// if let Some(num) = s.downcast_mut::<u32>() {
	/// *num = 42;
	/// }
	/// }
	///
	/// let mut x = 10u32;
	/// let mut s = "starlord".to_string();
	///
	/// modify_if_u32(&mut x);
	/// modify_if_u32(&mut s);
	///
	/// assert_eq!(x, 42);
	/// assert_eq!(&s, "starlord");
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[inline]
	pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
	Any::downcast_mut::<T>(self)
	}
	}

	impl dyn Any + Send + Sync {
	/// Forwards to the method defined on the type `Any`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn is_string(s: &(dyn Any + Send + Sync)) {
	/// if s.is::<String>() {
	/// println!("It's a string!");
	/// } else {
	/// println!("Not a string...");
	/// }
	/// }
	///
	/// is_string(&0);
	/// is_string(&"cookie monster".to_string());
	/// ```
	#[stable(feature = "any_send_sync_methods", since = "1.28.0")]
	#[inline]
	pub fn is<T: Any>(&self) -> bool {
	Any::is::<T>(self)
	}

	/// Forwards to the method defined on the type `Any`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn print_if_string(s: &(dyn Any + Send + Sync)) {
	/// if let Some(string) = s.downcast_ref::<String>() {
	/// println!("It's a string({}): '{}'", string.len(), string);
	/// } else {
	/// println!("Not a string...");
	/// }
	/// }
	///
	/// print_if_string(&0);
	/// print_if_string(&"cookie monster".to_string());
	/// ```
	#[stable(feature = "any_send_sync_methods", since = "1.28.0")]
	#[inline]
	pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
	Any::downcast_ref::<T>(self)
	}

	/// Forwards to the method defined on the type `Any`.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::Any;
	///
	/// fn modify_if_u32(s: &mut (dyn Any + Send + Sync)) {
	/// if let Some(num) = s.downcast_mut::<u32>() {
	/// *num = 42;
	/// }
	/// }
	///
	/// let mut x = 10u32;
	/// let mut s = "starlord".to_string();
	///
	/// modify_if_u32(&mut x);
	/// modify_if_u32(&mut s);
	///
	/// assert_eq!(x, 42);
	/// assert_eq!(&s, "starlord");
	/// ```
	#[stable(feature = "any_send_sync_methods", since = "1.28.0")]
	#[inline]
	pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
	Any::downcast_mut::<T>(self)
	}
	}

	///////////////////////////////////////////////////////////////////////////////
	// TypeID and its methods
	///////////////////////////////////////////////////////////////////////////////

	/// A `TypeId` represents a globally unique identifier for a type.
	///
	/// Each `TypeId` is an opaque object which does not allow inspection of what's
	/// inside but does allow basic operations such as cloning, comparison,
	/// printing, and showing.
	///
	/// A `TypeId` is currently only available for types which ascribe to `'static`,
	/// but this limitation may be removed in the future.
	///
	/// While `TypeId` implements `Hash`, `PartialOrd`, and `Ord`, it is worth
	/// noting that the hashes and ordering will vary between Rust releases. Beware
	/// of relying on them inside of your code!
	#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
	#[stable(feature = "rust1", since = "1.0.0")]
	pub struct TypeId {
	t: u64,
	}

	impl TypeId {
	/// Returns the `TypeId` of the type this generic function has been
	/// instantiated with.
	///
	/// # Examples
	///
	/// ```
	/// use std::any::{Any, TypeId};
	///
	/// fn is_string<T: ?Sized + Any>(_s: &T) -> bool {
	/// TypeId::of::<String>() == TypeId::of::<T>()
	/// }
	///
	/// assert_eq!(is_string(&0), false);
	/// assert_eq!(is_string(&"cookie monster".to_string()), true);
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[rustc_const_unstable(feature = "const_type_id", issue = "41875")]
	pub const fn of<T: ?Sized + 'static>() -> TypeId {
	TypeId { t: intrinsics::type_id::<T>() }
	}
	}

	/// Returns the name of a type as a string slice.
	///
	/// # Note
	///
	/// This is intended for diagnostic use. The exact contents and format of the
	/// string are not specified, other than being a best-effort description of the
	/// type. For example, `type_name::<Option<String>>()` could return the
	/// `"Option<String>"` or `"std::option::Option<std::string::String>"`, but not
	/// `"foobar"`. In addition, the output may change between versions of the
	/// compiler.
	///
	/// The type name should not be considered a unique identifier of a type;
	/// multiple types may share the same type name.
	///
	/// The current implementation uses the same infrastructure as compiler
	/// diagnostics and debuginfo, but this is not guaranteed.
	///
	/// # Examples
	///
	/// ```rust
	/// assert_eq!(
	/// std::any::type_name::<Option<String>>(),
	/// "core::option::Option<alloc::string::String>",
	/// );
	/// ```
	#[stable(feature = "type_name", since = "1.38.0")]
	#[rustc_const_unstable(feature = "const_type_name", issue = "63084")]
	pub const fn type_name<T: ?Sized>() -> &'static str {
	intrinsics::type_name::<T>()
	}

	/// Returns the name of the type of the pointed-to value as a string slice.
	/// This is the same as `type_name::<T>()`, but can be used where the type of a
	/// variable is not easily available.
	///
	/// # Note
	///
	/// This is intended for diagnostic use. The exact contents and format of the
	/// string are not specified, other than being a best-effort description of the
	/// type. For example, `type_name_of::<Option<String>>(None)` could return
	/// `"Option<String>"` or `"std::option::Option<std::string::String>"`, but not
	/// `"foobar"`. In addition, the output may change between versions of the
	/// compiler.
	///
	/// The type name should not be considered a unique identifier of a type;
	/// multiple types may share the same type name.
	///
	/// The current implementation uses the same infrastructure as compiler
	/// diagnostics and debuginfo, but this is not guaranteed.
	///
	/// # Examples
	///
	/// Prints the default integer and float types.
	///
	/// ```rust
	/// #![feature(type_name_of_val)]
	/// use std::any::type_name_of_val;
	///
	/// let x = 1;
	/// println!("{}", type_name_of_val(&x));
	/// let y = 1.0;
	/// println!("{}", type_name_of_val(&y));
	/// ```
	#[unstable(feature = "type_name_of_val", issue = "66359")]
	#[rustc_const_unstable(feature = "const_type_name", issue = "63084")]
	pub const fn type_name_of_val<T: ?Sized>(_val: &T) -> &'static str {
	type_name::<T>()
	}