Warning "variant is never used" is confusing when programmer just woke up

[nox]

I was changing some code from integer constants to a proper enum and was greeted by the following warning:

   Compiling script v0.0.1 (file:///Users/nox/src/servo/components/script)
warning: variant is never used: `HaveMetadata`
  --> /Users/nox/src/servo/components/script/dom/htmlmediaelement.rs:88:5
   |
88 |     HaveMetadata = HTMLMediaElementConstants::HAVE_METADATA as u8,
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: #[warn(dead_code)] on by default

The warning sounded weird to me because I was pattern-matching on that damn variant in various places of the code; but I was pointed out to the fact that I wasn't actually creating that value.

Maybe the warning should be rewritten to explicitly mention value creation?

Cc @arielb1

[arielb1]

cc @Manishearth that looks like your thing

[ollie27]

duplicate of #19140

[steveklabnik]

Yup! Closing in favor of that.