From 1d05f81d19084be01a172205b091bbfe4dd4e5fa Mon Sep 17 00:00:00 2001 From: Taiki Endo Date: Thu, 7 Feb 2019 19:44:06 +0900 Subject: [PATCH] Add #[must_use] message to Fn* traits --- src/libcore/ops/function.rs | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/libcore/ops/function.rs b/src/libcore/ops/function.rs index 3a1d765f7b8..c69f5fd9896 100644 --- a/src/libcore/ops/function.rs +++ b/src/libcore/ops/function.rs @@ -62,7 +62,7 @@ label="expected an `Fn<{Args}>` closure, found `{Self}`", )] #[fundamental] // so that regex can rely that `&str: !FnMut` -#[must_use] +#[must_use = "closures are lazy and do nothing unless called"] pub trait Fn : FnMut { /// Performs the call operation. #[unstable(feature = "fn_traits", issue = "29625")] @@ -141,7 +141,7 @@ pub trait Fn : FnMut { label="expected an `FnMut<{Args}>` closure, found `{Self}`", )] #[fundamental] // so that regex can rely that `&str: !FnMut` -#[must_use] +#[must_use = "closures are lazy and do nothing unless called"] pub trait FnMut : FnOnce { /// Performs the call operation. #[unstable(feature = "fn_traits", issue = "29625")] @@ -220,7 +220,7 @@ pub trait FnMut : FnOnce { label="expected an `FnOnce<{Args}>` closure, found `{Self}`", )] #[fundamental] // so that regex can rely that `&str: !FnMut` -#[must_use] +#[must_use = "closures are lazy and do nothing unless called"] pub trait FnOnce { /// The returned type after the call operator is used. #[stable(feature = "fn_once_output", since = "1.12.0")]