Parse error relating to `where` clause in associated type

[Ken Micklas]

Here is a minimal example which rustc accepts.

trait T {
    type AT;

    fn foo();
}

impl T for S {
    type AT = u8 where 'static: 'static;

    fn foo() {
        drop(3)
    }
}

#[derive()]
pub struct S {}

fn main() {}

The interesting line which makes it go all wrong seems to be

    type AT = u8 where 'static: 'static;

however the remaining code causes some cascading failures.

Here is the output of tree-sitter parse, with the grammar as of 17a6b15:

Warning: You have not configured any parser directories!
Please run `tree-sitter init-config` and edit the resulting
configuration file to indicate where we should look for
language grammars.

(source_file [0, 0] - [18, 0]
  (trait_item [0, 0] - [4, 1]
    name: (type_identifier [0, 6] - [0, 7])
    body: (declaration_list [0, 8] - [4, 1]
      (associated_type [1, 4] - [1, 12]
        name: (type_identifier [1, 9] - [1, 11]))
      (function_signature_item [3, 4] - [3, 13]
        name: (identifier [3, 7] - [3, 10])
        parameters: (parameters [3, 10] - [3, 12]))))
  (ERROR [6, 0] - [17, 12]
    (identifier [6, 5] - [6, 6])
    (type_identifier [6, 11] - [6, 12])
    (identifier [7, 9] - [7, 11])
    (ERROR [7, 14] - [9, 14]
      (primitive_type [7, 14] - [7, 16])
      (lifetime [7, 23] - [7, 30]
        (identifier [7, 24] - [7, 30]))
      (lifetime [7, 32] - [7, 39]
        (identifier [7, 33] - [7, 39]))
      (function_type [9, 7] - [9, 12]
        trait: (type_identifier [9, 7] - [9, 10])
        parameters: (parameters [9, 10] - [9, 12])))
    (identifier [10, 8] - [10, 12])
    (ERROR [10, 13] - [12, 1]
      (integer_literal [10, 13] - [10, 14]))
    (attribute_item [14, 0] - [14, 11]
      (attribute [14, 2] - [14, 10]
        (identifier [14, 2] - [14, 8])
        arguments: (token_tree [14, 8] - [14, 10])))
    (ERROR [15, 0] - [17, 2]
      (struct_pattern [15, 0] - [15, 15]
        type: (type_identifier [15, 0] - [15, 3])
        (ERROR [15, 4] - [15, 12]
          (identifier [15, 4] - [15, 10])
          (identifier [15, 11] - [15, 12])))
      (identifier [17, 0] - [17, 2]))
    (struct_pattern [17, 3] - [17, 12]
      type: (type_identifier [17, 3] - [17, 7])
      (ERROR [17, 7] - [17, 9]
        (parameters [17, 7] - [17, 9])))))
test.rs 0 ms    (ERROR [6, 0] - [17, 12])