From fb7deda27419eae61da3cbf5a5b1b4f51ae16d04 Mon Sep 17 00:00:00 2001 From: Scott McMurray Date: Fri, 30 Mar 2018 23:06:05 -0700 Subject: Add #[must_use] to a few standard library methods Chosen to start a precedent of using it on ones that are potentially-expensive and where using it for side effects is particularly discouraged. Discuss :) --- src/libcore/clone.rs | 1 + src/libcore/iter/iterator.rs | 1 + 2 files changed, 2 insertions(+) (limited to 'src/libcore') diff --git a/src/libcore/clone.rs b/src/libcore/clone.rs index d25f498b99e..c175ae15d28 100644 --- a/src/libcore/clone.rs +++ b/src/libcore/clone.rs @@ -105,6 +105,7 @@ pub trait Clone : Sized { /// assert_eq!("Hello", hello.clone()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] + #[must_use = "cloning is often expensive and is not expected to have side effects"] fn clone(&self) -> Self; /// Performs copy-assignment from `source`. diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs index 31f77f92435..42fd9051292 100644 --- a/src/libcore/iter/iterator.rs +++ b/src/libcore/iter/iterator.rs @@ -1368,6 +1368,7 @@ pub trait Iterator { /// [`Result`]: ../../std/result/enum.Result.html #[inline] #[stable(feature = "rust1", since = "1.0.0")] + #[must_use = "if you really need to exhaust the iterator, consider `.for_each(drop)` instead"] fn collect>(self) -> B where Self: Sized { FromIterator::from_iter(self) } -- cgit 1.4.1-3-g733a5