// Copyright 2015 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. // issue #21405 // ignore-tidy-linelength struct Foo; fn foo(f: F) where F: FnMut(Foo) {} fn main() { foo(|s| s.is_empty()); //~^ ERROR no method named `is_empty` found //~^^ HELP #1: `std::iter::ExactSizeIterator` //~^^^ HELP #2: `core::slice::SliceExt` //~^^^^ HELP #3: `core::str::StrExt` //~^^^^^ HELP items from traits can only be used if the trait is implemented and in scope; the following traits define an item `is_empty`, perhaps you need to implement one of them: }