From 3ab60264b504c1f51b2a9e3dfa20ef0d03bcdaed Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Esteban=20K=C3=BCber?= Date: Thu, 25 Jul 2019 10:11:03 -0700 Subject: [PATCH] Add note suggesting to borrow a String argument to find --- src/libcore/ops/function.rs | 4 ++++ src/test/ui/suggestions/issue-62843.rs | 5 +++++ src/test/ui/suggestions/issue-62843.stderr | 13 +++++++++++++ 3 files changed, 22 insertions(+) create mode 100644 src/test/ui/suggestions/issue-62843.rs create mode 100644 src/test/ui/suggestions/issue-62843.stderr diff --git a/src/libcore/ops/function.rs b/src/libcore/ops/function.rs index c69f5fd9896..b9552eaa1a0 100644 --- a/src/libcore/ops/function.rs +++ b/src/libcore/ops/function.rs @@ -137,6 +137,10 @@ pub trait Fn : FnMut { #[rustc_paren_sugar] #[rustc_on_unimplemented( on(Args="()", note="wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}"), + on( + all(Args="(char,)", _Self="std::string::String"), + note="borrowing the `{Self}` might fix the problem" + ), message="expected a `{FnMut}<{Args}>` closure, found `{Self}`", label="expected an `FnMut<{Args}>` closure, found `{Self}`", )] diff --git a/src/test/ui/suggestions/issue-62843.rs b/src/test/ui/suggestions/issue-62843.rs new file mode 100644 index 00000000000..d96b12fd15a --- /dev/null +++ b/src/test/ui/suggestions/issue-62843.rs @@ -0,0 +1,5 @@ +fn main() { + let line = String::from("abc"); + let pattern = String::from("bc"); + println!("{:?}", line.find(pattern)); //~ ERROR E0277 +} diff --git a/src/test/ui/suggestions/issue-62843.stderr b/src/test/ui/suggestions/issue-62843.stderr new file mode 100644 index 00000000000..cc27b5b49b6 --- /dev/null +++ b/src/test/ui/suggestions/issue-62843.stderr @@ -0,0 +1,13 @@ +error[E0277]: expected a `std::ops::FnMut<(char,)>` closure, found `std::string::String` + --> $DIR/issue-62843.rs:4:27 + | +LL | println!("{:?}", line.find(pattern)); + | ^^^^ expected an `FnMut<(char,)>` closure, found `std::string::String` + | + = help: the trait `std::ops::FnMut<(char,)>` is not implemented for `std::string::String` + = note: borrowing the `std::string::String` might fix the problem + = note: required because of the requirements on the impl of `std::str::pattern::Pattern<'_>` for `std::string::String` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`.