Constant rustc::hir::def_id::LOCAL_CRATE []

pub const LOCAL_CRATE: CrateNum = CrateNum(0)
🔬 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?

Item definitions in the currently-compiled crate would have the CrateNum LOCAL_CRATE in their DefId.