No recovery when expecting `>` as a token prefix

[ahoppen]

Issue Kind

Bad Diagnostic Produced

Source Code

protocol Test<Foo Bar> {}

Description

Produces the following diagnostics

1 │ protocol Test<Foo Bar> {}
  │                   ├─ error: expected '>' to end primary associated type clause
  │                   ╰─ error: unexpected code 'Bar>' in protocol

We should be consuming Bar as an unexpected token when looking for the closing > in the primary associated value clause. The tricky part is that none of our recovery infrastructure supports the recovery to a token prefix.

Came up in #1910 (comment)

[ahoppen]

Tracked in Apple’s issue tracker as rdar://112473319