Module rustc_span::def_id
source · Structs
A
DefId identifies a particular definition, by combining a crate
index and a def index.A DefIndex is an index into the hir-map for a crate, identifying a
particular definition. It should really be considered an interned
shorthand for a particular DefPath.
A
DefPathHash is a fixed-size representation of a DefPath that is
stable across crate and compilation session boundaries. It consists of two
separate 64-bit hashes. The first uniquely identifies the crate this
DefPathHash originates from (see StableCrateId), and the second
uniquely identifies the corresponding DefPath within that crate. Together
they form a unique identifier within an entire crate graph.A
LocalDefId is equivalent to a DefId with krate == LOCAL_CRATE. Since
we encode this information in the type, we can ensure at compile time that
no DefIds from upstream crates get thrown into the mix. There are quite a
few cases where we know that only DefIds from the local crate are expected;
a DefId from a different crate would signify a bug somewhere. This
is when LocalDefId comes in handy.A
StableCrateId is a 64-bit hash of a crate name, together with all
-Cmetadata arguments, and some other data. It is to CrateNum what DefPathHash is to
DefId. It is stable across compilation sessions.Constants
The crate root is always assigned index 0 by the AST Map code,
thanks to
NodeCollector::new.Item definitions in the currently-compiled crate would have the
CrateNum
LOCAL_CRATE in their DefId.