Lang item attributes are not handled on enum variants

Summary

Lang item attributes on enum variants are not handled.

Reproducer

I tried this code:

#![feature(no_core, lang_items)]
#![no_core]

pub enum Poll {
    #[lang = "Ready_wrong"]
    Ready,
    #[lang = "Pending_wrong"]
    Pending
}

Does the code make use of any (1.49) nightly feature ?

• Nightly

Godbolt link

https://godbolt.org/z/e963es8Yq

Actual behavior

Compiler returned: 0

Expected behavior

error[E0522]: definition of an unknown language item: `Ready_wrong`
 --> <source>:5:5
  |
5 |     #[lang = "Ready_wrong"]
  |     ^^^^^^^^^^^^^^^^^^^^^^^ definition of unknown language item `Ready_wrong`

error[E0522]: definition of an unknown language item: `Pending_wrong`
 --> <source>:7:5
  |
7 |     #[lang = "Pending_wrong"]
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^ definition of unknown language item `Pending_wrong`

GCC Version

master