error: unnecessary parentheses around type
  --> $DIR/issue-105061.rs:12:6
   |
LL |     ((for<'a> fn(Inv<'a>)),): Trait,
   |      ^                   ^
   |
note: the lint level is defined here
  --> $DIR/issue-105061.rs:2:9
   |
LL | #![deny(warnings)]
   |         ^^^^^^^^
   = note: `#[deny(unused_parens)]` implied by `#[deny(warnings)]`
help: remove these parentheses
   |
LL -     ((for<'a> fn(Inv<'a>)),): Trait,
LL +     (for<'a> fn(Inv<'a>),): Trait,
   |

error: aborting due to 1 previous error