Implement `IntoDiagnosticArg` for `&'a T` when `T` implements `IntoDiagnosticArg` and `Clone`. Makes it easier to write diagnostic structs that borrow something which implements `IntoDiagnosticArg`. Signed-off-by: David Wood <david.wood@huawei.com>
Implement `IntoDiagnosticArg` for `&'a T` when `T` implements `IntoDiagnosticArg` and `Clone`. Makes it easier to write diagnostic structs that borrow something which implements `IntoDiagnosticArg`. Signed-off-by: David Wood <david.wood@huawei.com>