Poor error suggestion from failure to use trait

[jnqnfe]

Forwarding: rust-num/num-derive#44

As described in the above issue originally filed against num-derive, I experienced a very poor suggestion in the error message resulting from forgetting to use the trait in question.

I'll duplicate the error here, but please see the linked issue for full details.

error[E0599]: no variant or associated item named `from_i32` found for enum `capi::pa_port_available_t` in the current scope
   --> pulse-binding/src/context/introspect.rs:351:48
    |
351 |                 available: def::PortAvailable::from_i32(src.available).unwrap(),
    |                                                ^^^^^^^^ variant or associated item not found in `capi::pa_port_available_t`
    |
    = help: items from traits can only be used if the trait is in scope
    = note: the following trait is implemented but not in scope; perhaps add a `use` for it:
            `use crate::channelmap::_IMPL_NUM_ToPrimitive_FOR_Position::_num_traits::FromPrimitive;`

Clearly the trait referenced in that suggestion is not one that Rust should be making.

Additionally I pointed out a secondary lesser issue with the type name used in the error being unhelpful as it uses the original name rather than the re-exported name.

I'm currently on Rust 1.47 (Debian Sid).