rust/src/test/compile-fail/trait-bounds-impl-comparison-1.rs
Patrick Walton e56dbad9f7 librustc: Properly compare implementation method type parameter bounds
with the corresponding trait parameter bounds.

This is a version of the patch in PR #12611 by Florian Hahn, modified to
address Niko's feedback.

It does not address the issue of duplicate type parameter bounds, nor
does it address the issue of implementation-defined methods that contain
*fewer* bounds than the trait, because Niko's review indicates that this
should not be necessary (and indeed I believe it is not). A test has
been added to ensure that this works.

This will break code like:

    trait Foo {
        fn bar<T:Baz>();
    }

    impl Foo for Boo {
        fn bar<T:Baz + Quux>() { ... }
        //             ^~~~ ERROR
    }

This will be rejected because the implementation requires *more* bounds
than the trait. It can be fixed by either adding the missing bound to
the trait:

    trait Foo {
        fn bar<T:Baz + Quux>();
        //             ^~~~
    }

    impl Foo for Boo {
        fn bar<T:Baz + Quux>() { ... }  // OK
    }

Or by removing the bound from the impl:

    trait Foo {
        fn bar<T:Baz>();
    }

    impl Foo for Boo {
        fn bar<T:Baz>() { ... }  // OK
        //       ^ remove Quux
    }

This patch imports the relevant tests from #2687, as well as the test
case in #5886, which is fixed as well by this patch.

Closes #2687.
Closes #5886.

[breaking-change]
2014-07-01 21:59:16 -07:00

79 lines
2.5 KiB
Rust

// 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.
//
// Make sure rustc checks the type parameter bounds in implementations of traits,
// see #2687
trait A {}
trait B: A {}
trait C: A {}
trait Foo {
fn test_error1_fn<T: Eq>(&self);
fn test_error2_fn<T: Eq + Ord>(&self);
fn test_error3_fn<T: Eq + Ord>(&self);
fn test3_fn<T: Eq + Ord>(&self);
fn test4_fn<T: Eq + Ord>(&self);
fn test_error5_fn<T: A>(&self);
fn test6_fn<T: A + Eq>(&self);
fn test_error7_fn<T: A>(&self);
fn test_error8_fn<T: B>(&self);
}
impl Foo for int {
// invalid bound for T, was defined as Eq in trait
fn test_error1_fn<T: Ord>(&self) {}
//~^ ERROR in method `test_error1_fn`, type parameter 0 requires bound `core::cmp::Ord`
// invalid bound for T, was defined as Eq + Ord in trait
fn test_error2_fn<T: Eq + B>(&self) {}
//~^ ERROR in method `test_error2_fn`, type parameter 0 requires bound `B`
// invalid bound for T, was defined as Eq + Ord in trait
fn test_error3_fn<T: B + Eq>(&self) {}
//~^ ERROR in method `test_error3_fn`, type parameter 0 requires bound `B`
// multiple bounds, same order as in trait
fn test3_fn<T: Ord + Eq>(&self) {}
// multiple bounds, different order as in trait
fn test4_fn<T: Eq + Ord>(&self) {}
// parameters in impls must be equal or more general than in the defining trait
fn test_error5_fn<T: B>(&self) {}
//~^ ERROR in method `test_error5_fn`, type parameter 0 requires bound `B`
// bound `std::cmp::Eq` not enforced by this implementation, but this is OK
fn test6_fn<T: A>(&self) {}
fn test_error7_fn<T: A + Eq>(&self) {}
//~^ ERROR in method `test_error7_fn`, type parameter 0 requires bound `core::cmp::Eq`
fn test_error8_fn<T: C>(&self) {}
//~^ ERROR in method `test_error8_fn`, type parameter 0 requires bound `C`
}
trait Getter<T> { }
trait Trait {
fn method<G:Getter<int>>();
}
impl Trait for uint {
fn method<G: Getter<uint>>() {}
//~^ ERROR in method `method`, type parameter 0 requires bound `Getter<uint>`
}
fn main() {}