error[E0282]: type annotations needed for `Vec<T>`
  --> $DIR/method-ambig-one-trait-unknown-int-type.rs:24:9
   |
LL |     let mut x = Vec::new();
   |         ^^^^^
   |
help: consider giving `x` an explicit type, where the type for type parameter `T` is specified
   |
LL |     let mut x: Vec<T> = Vec::new();
   |              ++++++++

error[E0283]: type annotations needed
  --> $DIR/method-ambig-one-trait-unknown-int-type.rs:26:7
   |
LL |     x.foo();
   |       ^^^
   |
note: multiple `impl`s satisfying `Vec<_>: Foo` found
  --> $DIR/method-ambig-one-trait-unknown-int-type.rs:9:1
   |
LL | impl Foo for Vec<usize> {
   | ^^^^^^^^^^^^^^^^^^^^^^^
...
LL | impl Foo for Vec<isize> {
   | ^^^^^^^^^^^^^^^^^^^^^^^
help: try using a fully qualified path to specify the expected types
   |
LL |     <Vec<T> as Foo>::foo(&x);
   |     ++++++++++++++++++++++ ~

error[E0308]: mismatched types
  --> $DIR/method-ambig-one-trait-unknown-int-type.rs:33:20
   |
LL |     let y: usize = x.foo();
   |            -----   ^^^^^^^ expected `usize`, found `isize`
   |            |
   |            expected due to this
   |
help: you can convert an `isize` to a `usize` and panic if the converted value doesn't fit
   |
LL |     let y: usize = x.foo().try_into().unwrap();
   |                           ++++++++++++++++++++

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0282, E0283, E0308.
For more information about an error, try `rustc --explain E0282`.