error[E0283]: type annotations needed
  --> $DIR/auto-trait-selection.rs:15:16
   |
LL |     if false { is_trait(foo()) } else { Default::default() }
   |                ^^^^^^^^ ----- type must be known at this point
   |                |
   |                cannot infer type of the type parameter `T` declared on the function `is_trait`
   |
   = note: cannot satisfy `_: Trait<_>`
note: required by a bound in `is_trait`
  --> $DIR/auto-trait-selection.rs:7:16
   |
LL | fn is_trait<T: Trait<U>, U: Default>(_: T) -> U {
   |                ^^^^^^^^ required by this bound in `is_trait`
help: consider specifying the generic arguments
   |
LL |     if false { is_trait::<T, U>(foo()) } else { Default::default() }
   |                        ++++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0283`.