| // Copyright 2012 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. |
| |
| // Test that we correctly infer variance for region parameters in |
| // various self-contained types. |
| |
| #![feature(rustc_attrs)] |
| |
| // Regions that just appear in normal spots are contravariant: |
| |
| #[rustc_variance] |
| struct Test2<'a, 'b, 'c> { //~ ERROR regions=[[-, -, -];[];[]] |
| x: &'a isize, |
| y: &'b [isize], |
| c: &'c str |
| } |
| |
| // Those same annotations in function arguments become covariant: |
| |
| #[rustc_variance] |
| struct Test3<'a, 'b, 'c> { //~ ERROR regions=[[+, +, +];[];[]] |
| x: extern "Rust" fn(&'a isize), |
| y: extern "Rust" fn(&'b [isize]), |
| c: extern "Rust" fn(&'c str), |
| } |
| |
| // Mutability induces invariance: |
| |
| #[rustc_variance] |
| struct Test4<'a, 'b:'a> { //~ ERROR regions=[[-, o];[];[]] |
| x: &'a mut &'b isize, |
| } |
| |
| // Mutability induces invariance, even when in a |
| // contravariant context: |
| |
| #[rustc_variance] |
| struct Test5<'a, 'b:'a> { //~ ERROR regions=[[+, o];[];[]] |
| x: extern "Rust" fn(&'a mut &'b isize), |
| } |
| |
| // Invariance is a trap from which NO ONE CAN ESCAPE. |
| // In other words, even though the `&'b isize` occurs in |
| // an argument list (which is contravariant), that |
| // argument list occurs in an invariant context. |
| |
| #[rustc_variance] |
| struct Test6<'a, 'b:'a> { //~ ERROR regions=[[-, o];[];[]] |
| x: &'a mut extern "Rust" fn(&'b isize), |
| } |
| |
| // No uses at all is bivariant: |
| |
| #[rustc_variance] |
| struct Test7<'a> { //~ ERROR regions=[[*];[];[]] |
| //~^ ERROR parameter `'a` is never used |
| x: isize |
| } |
| |
| // Try enums too. |
| |
| #[rustc_variance] |
| enum Test8<'a, 'b, 'c:'b> { //~ ERROR regions=[[+, -, o];[];[]] |
| Test8A(extern "Rust" fn(&'a isize)), |
| Test8B(&'b [isize]), |
| Test8C(&'b mut &'c str), |
| } |
| |
| fn main() {} |