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Update HIR chapter to use `HirId` instead of `NodeId` 

`NodeId`s are no longer used in the HIR. See #50928 for more information.
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Noah Lev 2021-12-04 18:22:01 -08:00 committed by Joshua Nelson
parent 7c8d7c57a4
commit 51146cd309
1 changed files with 7 additions and 12 deletions
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@ -96,21 +96,16 @@ with a HIR node.
[HIR map]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/hir/map/struct.Map.html
[number of methods]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/hir/map/struct.Map.html#methods
For example, if you have a [`DefId`], and you would like to convert it
to a [`NodeId`], you can use
[`tcx.hir().as_local_node_id(def_id)`][as_local_node_id]. This returns
an `Option<NodeId>` – this will be `None` if the def-id refers to
something outside of the current crate (since then it has no HIR
node), but otherwise returns `Some(n)` where `n` is the node-id of the
definition.
For example, if you have a [`LocalDefId`], and you would like to convert it
to a [`HirId`], you can use [`tcx.hir().local_def_id_to_hir_id(def_id)`][local_def_id_to_hir_id].
You need a `LocalDefId`, rather than a `DefId`, since only local items have HIR nodes.
[`NodeId`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_ast/node_id/struct.NodeId.html
[as_local_node_id]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/hir/map/struct.Map.html#method.as_local_node_id
[local_def_id_to_hir_id]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/hir/map/struct.Map.html#method.local_def_id_to_hir_id
Similarly, you can use [`tcx.hir().find(n)`][find] to lookup the node for a
[`NodeId`]. This returns a `Option<Node<'tcx>>`, where [`Node`] is an enum
defined in the map; by matching on this you can find out what sort of
node the node-id referred to and also get a pointer to the data
[`HirId`]. This returns a `Option<Node<'hir>>`, where [`Node`] is an enum
defined in the map. By matching on this, you can find out what sort of
node the `HirId` referred to and also get a pointer to the data
itself. Often, you know what sort of node `n` is – e.g. if you know
that `n` must be some HIR expression, you can do
[`tcx.hir().expect_expr(n)`][expect_expr], which will extract and return the