Remove rustc_hir_id crate.

`rustc_hir_id` is a very small crate containing some basic HIR types
(e.g. `HirId`) so that other crates can use them without depending on
`rustc_hir` (which is a much bigger crate).

However, `rustc_span` already has a module called `def_id` which also
contains some basic HIR types (e.g. `DefId`). So there's not much point
also have `rustc_hir_id`. This commit moves the contents of
`rustc_hir_id` into that module.

Author: nnethercote

Cargo.lock

@@ -3956,7 +3956,6 @@ dependencies = [
  "rustc_error_messages",
  "rustc_errors",
  "rustc_hashes",
- "rustc_hir_id",
  "rustc_index",
  "rustc_lint_defs",
  "rustc_macros",
@@ -3993,17 +3992,6 @@ dependencies = [
  "tracing",
 ]
 
-[[package]]
-name = "rustc_hir_id"
-version = "0.0.0"
-dependencies = [
- "rustc_data_structures",
- "rustc_index",
- "rustc_macros",
- "rustc_serialize",
- "rustc_span",
-]
-
 [[package]]
 name = "rustc_hir_pretty"
 version = "0.0.0"
@@ -4186,7 +4174,6 @@ version = "0.0.0"
 dependencies = [
  "rustc_data_structures",
  "rustc_error_messages",
- "rustc_hir_id",
  "rustc_macros",
  "rustc_serialize",
  "rustc_span",

compiler/rustc_hir/Cargo.toml

@@ -15,7 +15,6 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_hashes = { path = "../rustc_hashes" }
-rustc_hir_id = { path = "../rustc_hir_id" }
 rustc_index = { path = "../rustc_index" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }
 rustc_macros = { path = "../rustc_macros" }

compiler/rustc_hir/src/def.rs

@@ -512,7 +512,7 @@ impl DefKind {
 ///   pointing to the definition of `str_to_string` in the current crate.
 //
 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug, HashStable_Generic)]
-pub enum Res<Id = hir::HirId> {
+pub enum Res<Id = crate::def_id::HirId> {
     /// Definition having a unique ID (`DefId`), corresponds to something defined in user code.
     ///
     /// **Not bound to a specific namespace.**

compiler/rustc_hir/src/hir.rs

@@ -33,8 +33,7 @@ use tracing::debug;
 
 use crate::attrs::AttributeKind;
 use crate::def::{CtorKind, DefKind, MacroKinds, PerNS, Res};
-use crate::def_id::{DefId, LocalDefIdMap};
-pub(crate) use crate::hir_id::{HirId, ItemLocalId, ItemLocalMap, OwnerId};
+use crate::def_id::{DefId, HirId, ItemLocalId, ItemLocalMap, LocalDefIdMap, OwnerId};
 use crate::intravisit::{FnKind, VisitorExt};
 use crate::lints::DelayedLints;
 
@@ -4911,7 +4910,7 @@ impl<'hir> OwnerNode<'hir> {
             | OwnerNode::TraitItem(TraitItem { owner_id, .. })
             | OwnerNode::ImplItem(ImplItem { owner_id, .. })
             | OwnerNode::ForeignItem(ForeignItem { owner_id, .. }) => *owner_id,
-            OwnerNode::Crate(..) => crate::CRATE_HIR_ID.owner,
+            OwnerNode::Crate(..) => crate::def_id::CRATE_HIR_ID.owner,
             OwnerNode::Synthetic => unreachable!(),
         }
     }

compiler/rustc_hir/src/intravisit.rs

@@ -69,6 +69,7 @@ use rustc_ast::visit::{VisitorResult, try_visit, visit_opt, walk_list};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::{Ident, Span, Symbol};
 
+use crate::def_id::HirId;
 use crate::hir::*;
 
 pub trait IntoVisitor<'hir> {

compiler/rustc_hir/src/lib.rs

@@ -23,8 +23,11 @@ pub mod def_path_hash_map;
 pub mod definitions;
 pub mod diagnostic_items;
 pub use rustc_span::def_id;
+pub use rustc_span::def_id::{
+    CRATE_HIR_ID, CRATE_OWNER_ID, HirId, HirIdMap, HirIdMapEntry, HirIdSet, ItemLocalId,
+    ItemLocalMap, ItemLocalMapEntry, ItemLocalSet, OwnerId,
+};
 mod hir;
-pub use rustc_hir_id::{self as hir_id, *};
 pub mod intravisit;
 pub mod lang_items;
 pub mod limit;

compiler/rustc_hir/src/pat_util.rs

@@ -3,8 +3,8 @@ use std::iter::Enumerate;
 use rustc_span::{Ident, Span};
 
 use crate::def::{CtorOf, DefKind, Res};
-use crate::def_id::{DefId, DefIdSet};
-use crate::hir::{self, BindingMode, ByRef, HirId, PatKind};
+use crate::def_id::{DefId, DefIdSet, HirId};
+use crate::hir::{self, BindingMode, ByRef, PatKind};
 
 pub struct EnumerateAndAdjust<I> {
     enumerate: Enumerate<I>,

compiler/rustc_hir/src/stable_hash_impls.rs

@@ -1,12 +1,11 @@
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 use rustc_span::HashStableContext;
-use rustc_span::def_id::DefPathHash;
+use rustc_span::def_id::{DefPathHash, ItemLocalId};
 
 use crate::HashIgnoredAttrId;
 use crate::hir::{
     AttributeMap, BodyId, ForeignItemId, ImplItemId, ItemId, OwnerNodes, TraitItemId,
 };
-use crate::hir_id::ItemLocalId;
 
 impl<Hcx: HashStableContext> ToStableHashKey<Hcx> for BodyId {
     type KeyType = (DefPathHash, ItemLocalId);