Move node_id module from rustc_ast to rustc_span.

This puts it alongside `rustc_span::def_id`, which serves a similar
purpose.

This lets us remove `rustc_errors`'s dependency on `rustc_ast`,
completing the disentangling of the AST crates and the error crates.

Author: nnethercote

Cargo.lock

@@ -3908,7 +3908,6 @@ dependencies = [
  "anstream",
  "anstyle",
  "derive_setters",
- "rustc_ast",
  "rustc_data_structures",
  "rustc_error_codes",
  "rustc_error_messages",

compiler/rustc_ast/src/ast.rs

@@ -30,6 +30,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::tagged_ptr::Tag;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic, Walkable};
 pub use rustc_span::AttrId;
+pub use rustc_span::node_id::{self, CRATE_NODE_ID, DUMMY_NODE_ID, NodeId};
 use rustc_span::{
     ByteSymbol, DUMMY_SP, ErrorGuaranteed, HashStableContext, Ident, Span, Spanned, Symbol, kw,
     respan, sym,
@@ -370,8 +371,6 @@ impl ParenthesizedArgs {
     }
 }
 
-pub use crate::node_id::{CRATE_NODE_ID, DUMMY_NODE_ID, NodeId};
-
 /// Modifiers on a trait bound like `[const]`, `?` and `!`.
 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Debug, Walkable)]
 pub struct TraitBoundModifiers {

compiler/rustc_ast/src/lib.rs

@@ -29,7 +29,6 @@ pub mod entry;
 pub mod expand;
 pub mod format;
 pub mod mut_visit;
-pub mod node_id;
 pub mod token;
 pub mod tokenstream;
 pub mod visit;

compiler/rustc_errors/Cargo.toml

@@ -9,7 +9,6 @@ annotate-snippets = { version = "0.12.15", features = ["simd"] }
 anstream = "0.6.20"
 anstyle = "1.0.13"
 derive_setters = "0.1.6"
-rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_error_codes = { path = "../rustc_error_codes" }
 rustc_error_messages = { path = "../rustc_error_messages" }

compiler/rustc_errors/src/decorate_diag.rs

@@ -1,11 +1,11 @@
 use std::any::Any;
 
-/// This module provides types and traits for buffering lints until later in compilation.
-use rustc_ast::node_id::NodeId;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sync::{DynSend, DynSync};
 use rustc_error_messages::MultiSpan;
 use rustc_lint_defs::{AttributeLintKind, Lint, LintId};
+/// This module provides types and traits for buffering lints until later in compilation.
+use rustc_span::node_id::NodeId;
 
 use crate::{Diag, DiagCtxtHandle, Diagnostic, Level};
 

compiler/rustc_span/src/lib.rs

@@ -55,6 +55,7 @@ pub use hygiene::{
 pub mod def_id;
 use def_id::{CrateNum, DefId, DefIndex, DefPathHash, LOCAL_CRATE, LocalDefId, StableCrateId};
 pub mod edit_distance;
+pub mod node_id;
 mod span_encoding;
 pub use span_encoding::{DUMMY_SP, Span};