From 86599e0c749760342677f6ba195a5cbf2a9707c1 Mon Sep 17 00:00:00 2001
From: Faizaan Pervaiz <faizaan.pervaiz@gmail.com>
Date: Wed, 5 Mar 2025 17:51:55 +0000
Subject: [PATCH 1/3] Add `Result::map_or_default` and `Option::map_or_default`

---
 library/core/src/option.rs | 27 +++++++++++++++++++++++++++
 library/core/src/result.rs | 27 +++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index a9f06b92ad5dd..a4ff81ef79105 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -1226,6 +1226,33 @@ impl<T> Option<T> {
         }
     }
 
+    /// Maps an `Option<T>` to a `U` by applying function `f` if the contained value
+    /// is [`Some`], otherwise if [`None`], returns the [default value] for the type `U`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let x: Option<&str> = Some("hi");
+    /// let y: Option<&str> = None;
+    ///
+    /// assert_eq!(x.map_or_default(|x| x.len()), 2);
+    /// assert_eq!(y.map_or_default(|y| y.len()), 0);
+    /// ```
+    ///
+    /// [default value]: Default::default
+    #[inline]
+    #[unstable(feature = "result_option_map_or_default", issue = "none")]
+    pub fn map_or_default<U, F>(self, f: F) -> U
+    where
+        U: Default,
+        F: FnOnce(T) -> U,
+    {
+        match self {
+            Some(t) => f(t),
+            None => U::default(),
+        }
+    }
+
     /// Transforms the `Option<T>` into a [`Result<T, E>`], mapping [`Some(v)`] to
     /// [`Ok(v)`] and [`None`] to [`Err(err)`].
     ///
diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index 92b5cba153166..742fd5694e594 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs
@@ -830,6 +830,33 @@ impl<T, E> Result<T, E> {
         }
     }
 
+    /// Maps a `Result<T, E>` to a `U` by applying function `f` if the contained value
+    /// is [`Ok`], otherwise if [`Err`], returns the [default value] for the type `U`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let x: Result<_, &str> = Ok("foo");
+    /// let y: Result<&str, _> = Err("bar");
+    ///
+    /// assert_eq!(x.map_or_default(|x| x.len()), 3);
+    /// assert_eq!(y.map_or_default(|y| y.len()), 0);
+    /// ```
+    ///
+    /// [default value]: Default::default
+    #[inline]
+    #[unstable(feature = "result_option_map_or_default", issue = "none")]
+    pub fn map_or_default<U, F>(self, f: F) -> U
+    where
+        U: Default,
+        F: FnOnce(T) -> U,
+    {
+        match self {
+            Ok(t) => f(t),
+            Err(_) => U::default(),
+        }
+    }
+
     /// Maps a `Result<T, E>` to `Result<T, F>` by applying a function to a
     /// contained [`Err`] value, leaving an [`Ok`] value untouched.
     ///

From bfbc296e0048d93cf962cb82718fa80a6c65963c Mon Sep 17 00:00:00 2001
From: Faizaan Pervaiz <faizaan.pervaiz@gmail.com>
Date: Wed, 5 Mar 2025 18:35:22 +0000
Subject: [PATCH 2/3] missing doc feature

---
 library/core/src/option.rs | 2 ++
 library/core/src/result.rs | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index a4ff81ef79105..d12966183b7a2 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -1232,6 +1232,8 @@ impl<T> Option<T> {
     /// # Examples
     ///
     /// ```
+    /// #![feature(result_option_map_or_default)]
+    ///
     /// let x: Option<&str> = Some("hi");
     /// let y: Option<&str> = None;
     ///
diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index 742fd5694e594..cec3c02d65f2e 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs
@@ -836,6 +836,8 @@ impl<T, E> Result<T, E> {
     /// # Examples
     ///
     /// ```
+    /// #![feature(result_option_map_or_default)]
+    ///
     /// let x: Result<_, &str> = Ok("foo");
     /// let y: Result<&str, _> = Err("bar");
     ///

From 278070be3e2aa31d23b60c1287489808ffab8220 Mon Sep 17 00:00:00 2001
From: Faizaan Pervaiz <faizaan.pervaiz@gmail.com>
Date: Thu, 6 Mar 2025 13:24:06 +0000
Subject: [PATCH 3/3] add tracking issue

---
 library/core/src/option.rs | 2 +-
 library/core/src/result.rs | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index d12966183b7a2..3d7ec570f1016 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -1243,7 +1243,7 @@ impl<T> Option<T> {
     ///
     /// [default value]: Default::default
     #[inline]
-    #[unstable(feature = "result_option_map_or_default", issue = "none")]
+    #[unstable(feature = "result_option_map_or_default", issue = "138099")]
     pub fn map_or_default<U, F>(self, f: F) -> U
     where
         U: Default,
diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index cec3c02d65f2e..63f3fe57ab19b 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs
@@ -847,7 +847,7 @@ impl<T, E> Result<T, E> {
     ///
     /// [default value]: Default::default
     #[inline]
-    #[unstable(feature = "result_option_map_or_default", issue = "none")]
+    #[unstable(feature = "result_option_map_or_default", issue = "138099")]
     pub fn map_or_default<U, F>(self, f: F) -> U
     where
         U: Default,