Static rustc_lint::unused::UNUSED_ALLOCATION[]

static UNUSED_ALLOCATION: &Lint = &::lint::Lint{name: "UNUSED_ALLOCATION",
              default_level: ::lint::Warn,
              desc: "detects unnecessary allocations that can be eliminated",
              edition_deny: None,}
🔬 This is a nightly-only experimental API. (rustc_private)

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?