Use root prefix to access crates

[mamins1376]

I'm working on a project which defines a core module for itself in the codebase and does not use the core crate directly. The module is frequently used, so it's imported alongside other common stuff everywhere through use crate::*.

However, when I tried using serde_repr I hit an strange error:

error[E0433]: failed to resolve: could not find `result` in `core`
 --> src/lib.rs:7:26
  |
7 | #[derive(Serialize_repr, Deserialize_repr, PartialEq, Eq, Debug)]
  |                          ^^^^^^^^^^^^^^^^ could not find `result` in `core`
  |
  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider importing one of these items
  |
1 | use core::fmt::Result;
  |
1 | use core::result::Result;
  |
1 | use serde::__private::Result;
  |
1 | use serde::__private::fmt::Result;
  |
    and 4 other candidates

After taking a look in the source code it turns out no :: prefix is being used (e.g. ::core::result::Result instead of core::result::Result), which seems to be the cause.

To reproduce:

use serde_repr::{Serialize_repr, Deserialize_repr};

mod core {}

#[derive(Serialize_repr, Deserialize_repr, PartialEq, Eq, Debug)]
#[repr(u8)]
enum E { V = 0 }

A temporary fix I currently use in the modules I use serde_repr:

use ::core;

Which is less than ideal.