src/test/ui/type-alias-bounds.rs

// Copyright 2014 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 ignored_generic_bounds lint warning about bounds in type aliases

// compile-pass
#![allow(dead_code)]

use std::rc::Rc;

type SVec<T: Send+Send> = Vec<T>;
//~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
type S2Vec<T> where T: Send = Vec<T>;
//~^ WARN where clauses are not enforced in type aliases [type_alias_bounds]
type VVec<'b, 'a: 'b+'b> = (&'b u32, Vec<&'a i32>);
//~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
type WVec<'b, T: 'b+'b> = (&'b u32, Vec<T>);
//~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
type W2Vec<'b, T> where T: 'b, T: 'b = (&'b u32, Vec<T>);
//~^ WARN where clauses are not enforced in type aliases [type_alias_bounds]

static STATIC : u32 = 0;

fn foo<'a>(y: &'a i32) {
    // If any of the bounds above would matter, the code below would be rejected.
    // This can be seen when replacing the type aliases above by newtype structs.
    // (The type aliases have no unused parameters to make that a valid transformation.)
    let mut x : SVec<_> = Vec::new();
    x.push(Rc::new(42)); // is not send

    let mut x : S2Vec<_> = Vec::new();
    x.push(Rc::new(42)); // is not send

    let mut x : VVec<'static, 'a> = (&STATIC, Vec::new());
    x.1.push(y); // 'a: 'static does not hold

    let mut x : WVec<'static, &'a i32> = (&STATIC, Vec::new());
    x.1.push(y); // &'a i32: 'static does not hold

    let mut x : W2Vec<'static, &'a i32> = (&STATIC, Vec::new());
    x.1.push(y); // &'a i32: 'static does not hold
}

// Bounds are not checked either, i.e. the definition is not necessarily well-formed
struct Sendable<T: Send>(T);
type MySendable<T> = Sendable<T>; // no error here!

// However, bounds *are* taken into account when accessing associated types
trait Bound { type Assoc; }
type T1<U: Bound> = U::Assoc; //~ WARN not enforced in type aliases
type T2<U> where U: Bound = U::Assoc;  //~ WARN not enforced in type aliases

// This errors
// type T3<U> = U::Assoc;
// Do this instead
type T4<U> = <U as Bound>::Assoc;

// Make sure the help about associatd types is not shown incorrectly
type T5<U: Bound> = <U as Bound>::Assoc;  //~ WARN not enforced in type aliases
type T6<U: Bound> = ::std::vec::Vec<U>;  //~ WARN not enforced in type aliases

fn main() {}