Rollup merge of rust-lang#138968 - Natural-selection1:update-Result-doc, r=Amanieu

Update the index of Result to make the summary more comprehensive

fix rust-lang#138966

This PR and rust-lang#138957 are twin PR

r? `@Amanieu`

Author: matthiaskrgr

core/src/result.rs

@@ -259,8 +259,14 @@
 //! The [`is_ok`] and [`is_err`] methods return [`true`] if the [`Result`]
 //! is [`Ok`] or [`Err`], respectively.
 //!
+//! The [`is_ok_and`] and [`is_err_and`] methods apply the provided function
+//! to the contents of the [`Result`] to produce a boolean value. If the [`Result`] does not have the expected variant
+//! then [`false`] is returned instead without executing the function.
+//!
 //! [`is_err`]: Result::is_err
 //! [`is_ok`]: Result::is_ok
+//! [`is_ok_and`]: Result::is_ok_and
+//! [`is_err_and`]: Result::is_err_and
 //!
 //! ## Adapters for working with references
 //!
@@ -287,6 +293,7 @@
 //!   (which must implement the [`Default`] trait)
 //! * [`unwrap_or_else`] returns the result of evaluating the provided
 //!   function
+//! * [`unwrap_unchecked`] produces *[undefined behavior]*
 //!
 //! The panicking methods [`expect`] and [`unwrap`] require `E` to
 //! implement the [`Debug`] trait.
@@ -297,17 +304,22 @@
 //! [`unwrap_or`]: Result::unwrap_or
 //! [`unwrap_or_default`]: Result::unwrap_or_default
 //! [`unwrap_or_else`]: Result::unwrap_or_else
+//! [`unwrap_unchecked`]: Result::unwrap_unchecked
+//! [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
 //!
 //! These methods extract the contained value in a [`Result<T, E>`] when it
 //! is the [`Err`] variant. They require `T` to implement the [`Debug`]
 //! trait. If the [`Result`] is [`Ok`]:
 //!
 //! * [`expect_err`] panics with a provided custom message
 //! * [`unwrap_err`] panics with a generic message
+//! * [`unwrap_err_unchecked`] produces *[undefined behavior]*
 //!
 //! [`Debug`]: crate::fmt::Debug
 //! [`expect_err`]: Result::expect_err
 //! [`unwrap_err`]: Result::unwrap_err
+//! [`unwrap_err_unchecked`]: Result::unwrap_err_unchecked
+//! [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
 //!
 //! ## Transforming contained values
 //!
@@ -330,21 +342,29 @@
 //! [`Some(v)`]: Option::Some
 //! [`transpose`]: Result::transpose
 //!
-//! This method transforms the contained value of the [`Ok`] variant:
+//! These methods transform the contained value of the [`Ok`] variant:
 //!
 //! * [`map`] transforms [`Result<T, E>`] into [`Result<U, E>`] by applying
 //!   the provided function to the contained value of [`Ok`] and leaving
 //!   [`Err`] values unchanged
+//! * [`inspect`] takes ownership of the [`Result`], applies the
+//!   provided function to the contained value by reference,
+//!   and then returns the [`Result`]
 //!
 //! [`map`]: Result::map
+//! [`inspect`]: Result::inspect
 //!
-//! This method transforms the contained value of the [`Err`] variant:
+//! These methods transform the contained value of the [`Err`] variant:
 //!
 //! * [`map_err`] transforms [`Result<T, E>`] into [`Result<T, F>`] by
 //!   applying the provided function to the contained value of [`Err`] and
 //!   leaving [`Ok`] values unchanged
+//! * [`inspect_err`] takes ownership of the [`Result`], applies the
+//!   provided function to the contained value of [`Err`] by reference,
+//!   and then returns the [`Result`]
 //!
 //! [`map_err`]: Result::map_err
+//! [`inspect_err`]: Result::inspect_err
 //!
 //! These methods transform a [`Result<T, E>`] into a value of a possibly
 //! different type `U`:
@@ -578,6 +598,10 @@ impl<T, E> Result<T, E> {
     ///
     /// let x: Result<u32, &str> = Err("hey");
     /// assert_eq!(x.is_ok_and(|x| x > 1), false);
+    ///
+    /// let x: Result<String, &str> = Ok("ownership".to_string());
+    /// assert_eq!(x.as_ref().is_ok_and(|x| x.len() > 1), true);
+    /// println!("still alive {:?}", x);
     /// ```
     #[must_use]
     #[inline]
@@ -623,6 +647,10 @@ impl<T, E> Result<T, E> {
     ///
     /// let x: Result<u32, Error> = Ok(123);
     /// assert_eq!(x.is_err_and(|x| x.kind() == ErrorKind::NotFound), false);
+    ///
+    /// let x: Result<u32, String> = Err("ownership".to_string());
+    /// assert_eq!(x.as_ref().is_err_and(|x| x.len() > 1), true);
+    /// println!("still alive {:?}", x);
     /// ```
     #[must_use]
     #[inline]