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Auto merge of #40565 - estebank:binops-help, r=arielb1

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Explicit help message for binop type mismatch

When trying to do `1 + Some(2)`, or some other binary operation on two
types different types without an appropriate trait implementation, provide
an explicit help message:

```rust
help: `{integer} + std::option::Option<{integer}>` has no implementation
```

Re: #39579, #38564, #37626, #39942, #34698.
This commit is contained in:
bors 2017-04-10 21:56:13 +00:00
commit 730e5ad04e
8 changed files with 164 additions and 17 deletions
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72
src/test/compile-fail/impl-trait/equality.rs
View file

@ -1,72 +0,0 @@
// Copyright 2016 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.
#![feature(conservative_impl_trait, specialization)]
trait Foo: Copy + ToString {}
impl<T: Copy + ToString> Foo for T {}
fn hide<T: Foo>(x: T) -> impl Foo {
x
}
fn two(x: bool) -> impl Foo {
if x {
return 1_i32;
}
0_u32
//~^ ERROR mismatched types
//~| expected i32, found u32
}
fn sum_to(n: u32) -> impl Foo {
if n == 0 {
0
} else {
n + sum_to(n - 1)
//~^ ERROR the trait bound `u32: std::ops::Add<impl Foo>` is not satisfied
}
}
trait Leak: Sized {
type T;
fn leak(self) -> Self::T;
}
impl<T> Leak for T {
default type T = ();
default fn leak(self) -> Self::T { panic!() }
}
impl Leak for i32 {
type T = i32;
fn leak(self) -> i32 { self }
}
fn main() {
let _: u32 = hide(0_u32);
//~^ ERROR mismatched types
//~| expected type `u32`
//~| found type `impl Foo`
//~| expected u32, found anonymized type
let _: i32 = Leak::leak(hide(0_i32));
//~^ ERROR mismatched types
//~| expected type `i32`
//~| found type `<impl Foo as Leak>::T`
//~| expected i32, found associated type
let mut x = (hide(0_u32), hide(0_i32));
x = (x.1,
//~^ ERROR mismatched types
//~| expected u32, found i32
x.0);
//~^ ERROR mismatched types
//~| expected i32, found u32
}