Rollup merge of #40518 - michaelwoerister:hir-id, r=eddyb

Introduce HirId, a replacement for ast::NodeId after lowering to HIR

This is the first step towards implementing #40303. This PR introduces the `HirId` type and generates a `HirId` for everything that would be assigned one (i.e. stuff in the HIR), but the HIR data types still use `NodeId` for now. Changing that is a big refactoring that I want to do in a separate PR.

A `HirId` uniquely identifies a node in the HIR of the current crate. It is composed of the `owner`, which is the `DefIndex` of the directly enclosing `hir::Item`, `hir::TraitItem`, or `hir::ImplItem` (i.e. the closest "item-like"), and the `local_id` which is unique within the given owner.

This PR is also running a number of consistency checks for the generated `HirId`s:
- Does `NodeId` in the HIR have a corresponding `HirId`?
- Is the `owner` part of each `HirId` consistent with its position in the HIR?
- Do the numerical values of the `local_id` part all lie within a dense range of integers?

cc @rust-lang/compiler

r? @eddyb or @nikomatsakis

1 files changed, 7 insertions, 0 deletions

diff --git a/src/librustc_data_structures/indexed_vec.rs b/src/librustc_data_structures/indexed_vec.rs
index 3f478d7c165..62c430dda32 100644
--- a/src/librustc_data_structures/indexed_vec.rs
+++ b/src/librustc_data_structures/indexed_vec.rs
@@ -189,6 +189,13 @@ impl<I: Idx, T> IndexVec<I, T> {
     }
 }
 
+impl<I: Idx, T: Clone> IndexVec<I, T> {
+    #[inline]
+    pub fn resize(&mut self, new_len: usize, value: T) {
+        self.raw.resize(new_len, value)
+    }
+}
+
 impl<I: Idx, T> Index<I> for IndexVec<I, T> {
     type Output = T;