feat: Add threading::make_mut() to allow obtaining a mutable reference to shared data.

This is particularly useful when handling an index file, which may be shared across clones of
a repository.

Author: Byron

gix-features/src/threading.rs

@@ -30,6 +30,11 @@ mod _impl {
         v.write()
     }
 
+    /// Get a mutable reference to the underlying data, with semantics similar to [Arc::make_mut()].
+    pub fn make_mut<T: Clone>(this: &mut OwnShared<T>) -> &mut T {
+        OwnShared::make_mut(this)
+    }
+
     /// Get a mutable reference through a [`Mutable`] for read-write access.
     pub fn lock<T>(v: &Mutable<T>) -> parking_lot::MutexGuard<'_, T> {
         v.lock()
@@ -75,6 +80,11 @@ mod _impl {
         v.borrow_mut()
     }
 
+    /// Get a mutable reference to the underlying data, with semantics similar to [Rc::make_mut()].
+    pub fn make_mut<T: Clone>(this: &mut OwnShared<T>) -> &mut T {
+        OwnShared::make_mut(this)
+    }
+
     /// Get a mutable reference through a [`Mutable`] for read-write access.
     pub fn lock<T>(v: &Mutable<T>) -> RefMut<'_, T> {
         v.borrow_mut()