rust/src/test/compile-fail/issue-5062.rs

// Copyright 2013-2015 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

fn main() { format!("{:?}", None); }
    //~^ ERROR unable to fully infer type(s) [E0282]
test: Update expected compile-fail message for E0282 2015-05-05 16:22:20 +00:00			`// Copyright 2013-2015 The Rust Project Developers. See the COPYRIGHT`
testsuite: Add various test cases Some are xfailed, some not, some existing ones get un-xfailed. 2013-03-21 22:00:29 +00:00			`// file at the top-level directory of this distribution and at`
			`// http://rust-lang.org/COPYRIGHT.`
			`//`
			`// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or`
			`// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license`
			`// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your`
			`// option. This file may not be copied, modified, or distributed`
			`// except according to those terms.`

core: split into fmt::Show and fmt::String fmt::Show is for debugging, and can and should be implemented for all public types. This trait is used with `{:?}` syntax. There still exists #[derive(Show)]. fmt::String is for types that faithfully be represented as a String. Because of this, there is no way to derive fmt::String, all implementations must be purposeful. It is used by the default format syntax, `{}`. This will break most instances of `{}`, since that now requires the type to impl fmt::String. In most cases, replacing `{}` with `{:?}` is the correct fix. Types that were being printed specifically for users should receive a fmt::String implementation to fix this. Part of #20013 [breaking-change] 2014-12-20 08:09:35 +00:00			`fn main() { format!("{:?}", None); }`
Improve error message for uninferrable types #38812 2017-01-24 15:19:36 +00:00			`//~^ ERROR unable to fully infer type(s) [E0282]`