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| author | Scott McMurray <scottmcm@users.noreply.github.com> | 2018-03-30 23:06:05 -0700 |
|---|---|---|
| committer | Scott McMurray <scottmcm@users.noreply.github.com> | 2018-03-30 23:06:05 -0700 |
| commit | fb7deda27419eae61da3cbf5a5b1b4f51ae16d04 (patch) | |
| tree | 9dc51de2af727ff8741edb1c3f2b1665374da21d | |
| parent | 80785a547d29519dbdb5781437ec318fb210b980 (diff) | |
| download | rust-fb7deda27419eae61da3cbf5a5b1b4f51ae16d04.tar.gz rust-fb7deda27419eae61da3cbf5a5b1b4f51ae16d04.zip | |
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 :)
| -rw-r--r-- | src/liballoc/borrow.rs | 1 | ||||
| -rw-r--r-- | src/libcore/clone.rs | 1 | ||||
| -rw-r--r-- | src/libcore/iter/iterator.rs | 1 | ||||
| -rw-r--r-- | src/librustc_mir/build/mod.rs | 2 |
4 files changed, 4 insertions, 1 deletions
diff --git a/src/liballoc/borrow.rs b/src/liballoc/borrow.rs index acae0daa86b..c6741ddb822 100644 --- a/src/liballoc/borrow.rs +++ b/src/liballoc/borrow.rs @@ -59,6 +59,7 @@ pub trait ToOwned { /// let vv: Vec<i32> = v.to_owned(); /// ``` #[stable(feature = "rust1", since = "1.0.0")] + #[must_use = "cloning is often expensive and is not expected to have side effects"] fn to_owned(&self) -> Self::Owned; /// Uses borrowed data to replace owned data, usually by cloning. 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<B: FromIterator<Self::Item>>(self) -> B where Self: Sized { FromIterator::from_iter(self) } diff --git a/src/librustc_mir/build/mod.rs b/src/librustc_mir/build/mod.rs index 8494c043f90..6f5fcc9e421 100644 --- a/src/librustc_mir/build/mod.rs +++ b/src/librustc_mir/build/mod.rs @@ -317,7 +317,7 @@ newtype_index!(ScopeId); /// macro (and methods below) makes working with `BlockAnd` much more /// convenient. -#[must_use] // if you don't use one of these results, you're leaving a dangling edge +#[must_use = "if you don't use one of these results, you're leaving a dangling edge"] struct BlockAnd<T>(BasicBlock, T); trait BlockAndExtension { |