Skip to content
Permalink
Browse files

Test illustrating that the nested_impl_trait lint should only catch s…

…hallow cases.
  • Loading branch information...
pnkfelix committed Mar 11, 2019
1 parent c993033 commit 837856d120ec3350f1e9d194801a6a89e5d71630
@@ -0,0 +1,42 @@
// rust-lang/rust#57979 : the initial support for `impl Trait` didn't
// properly check syntax hidden behind an associated type projection,
// but it did catch *some cases*. This is checking that we continue to
// properly emit errors for those, even with the new
// future-incompatibility warnings.
//
// issue-57979-nested-impl-trait-in-assoc-proj.rs shows the main case
// that we were previously failing to catch.

struct Deeper<T>(T);

mod allowed {
#![allow(nested_impl_trait)]

pub trait Foo<T> { }
pub trait Bar { }
pub trait Quux { type Assoc; }
pub fn demo(_: impl Quux<Assoc=super::Deeper<impl Foo<impl Bar>>>) { }
//~^ ERROR nested `impl Trait` is not allowed
}

mod warned {
#![warn(nested_impl_trait)]

pub trait Foo<T> { }
pub trait Bar { }
pub trait Quux { type Assoc; }
pub fn demo(_: impl Quux<Assoc=super::Deeper<impl Foo<impl Bar>>>) { }
//~^ ERROR nested `impl Trait` is not allowed
}

mod denied {
#![deny(nested_impl_trait)]

pub trait Foo<T> { }
pub trait Bar { }
pub trait Quux { type Assoc; }
pub fn demo(_: impl Quux<Assoc=super::Deeper<impl Foo<impl Bar>>>) { }
//~^ ERROR nested `impl Trait` is not allowed
}

fn main() { }
@@ -0,0 +1,30 @@
error[E0666]: nested `impl Trait` is not allowed
--> $DIR/issue-57979-deeply-nested-impl-trait-in-assoc-proj.rs:18:59
|
LL | pub fn demo(_: impl Quux<Assoc=super::Deeper<impl Foo<impl Bar>>>) { }
| ---------^^^^^^^^-
| | |
| | nested `impl Trait` here
| outer `impl Trait`

error[E0666]: nested `impl Trait` is not allowed
--> $DIR/issue-57979-deeply-nested-impl-trait-in-assoc-proj.rs:28:59
|
LL | pub fn demo(_: impl Quux<Assoc=super::Deeper<impl Foo<impl Bar>>>) { }
| ---------^^^^^^^^-
| | |
| | nested `impl Trait` here
| outer `impl Trait`

error[E0666]: nested `impl Trait` is not allowed
--> $DIR/issue-57979-deeply-nested-impl-trait-in-assoc-proj.rs:38:59
|
LL | pub fn demo(_: impl Quux<Assoc=super::Deeper<impl Foo<impl Bar>>>) { }
| ---------^^^^^^^^-
| | |
| | nested `impl Trait` here
| outer `impl Trait`

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0666`.

0 comments on commit 837856d

Please sign in to comment.
You can’t perform that action at this time.