E0599 error message may suggest syntactically invalid fix

[Rantanen]

Full code in Playground

Missing a trait bound for the trait that defines fn foo below:

fn do_stuff<T : Bar>(t : T) {  // Note the space before the colon in `T : Bar`
    t.foo()
}

Results in the following suggestion with an extra colon after the plus.

fn do_stuff<T: Foo +: Bar>(t : T) {

[estebank]

@varkor, you can look at https://github.com/rust-lang/rust/pull/65192/files#diff-0e12890ad498e250783f40f88a8b8ec6R978-R993 and https://github.com/rust-lang/rust/pull/65192/files#diff-0e12890ad498e250783f40f88a8b8ec6R1105-R1125 for inspiration on how to deal with this.

[varkor]

@estebank: I came up with a different solution, but there may be a subtlety I'm missing: #65289.