From 5e251b74eb200ba6d3b8ddaa68ef682c78be26e2 Mon Sep 17 00:00:00 2001 From: steveklabnik Date: Thu, 5 Oct 2017 16:54:56 -0400 Subject: [PATCH] Modify Rc/Arc language around mutability There are a few exceptions to the rule that Arc/Rc are immutable. Rather than dig into the details, add "generally" to hint at this difference, as it's kind of a distraction at this point in the docs. Additionally, Arc's docs were slightly different here generally, so add in both the existing language and the exception. Fixes #44105 --- src/liballoc/arc.rs | 6 ++++-- src/liballoc/rc.rs | 2 +- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs index 3b7dbd813cf0..9481cd4e1a4f 100644 --- a/src/liballoc/arc.rs +++ b/src/liballoc/arc.rs @@ -52,8 +52,10 @@ const MAX_REFCOUNT: usize = (isize::MAX) as usize; /// also destroyed. /// /// Shared references in Rust disallow mutation by default, and `Arc` is no -/// exception. If you need to mutate through an `Arc`, use [`Mutex`][mutex], -/// [`RwLock`][rwlock], or one of the [`Atomic`][atomic] types. +/// exception: you cannot generally obtain a mutable reference to something +/// inside an `Arc`. If you need to mutate through an `Arc`, use +/// [`Mutex`][mutex], [`RwLock`][rwlock], or one of the [`Atomic`][atomic] +/// types. /// /// ## Thread Safety /// diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs index 553980d463fc..2f8620cc7505 100644 --- a/src/liballoc/rc.rs +++ b/src/liballoc/rc.rs @@ -19,7 +19,7 @@ //! given value is destroyed, the pointed-to value is also destroyed. //! //! Shared references in Rust disallow mutation by default, and [`Rc`] -//! is no exception: you cannot obtain a mutable reference to +//! is no exception: you cannot generally obtain a mutable reference to //! something inside an [`Rc`]. If you need mutability, put a [`Cell`] //! or [`RefCell`] inside the [`Rc`]; see [an example of mutability //! inside an Rc][mutability].