Eliminate rustc_lint_defs' dependency on rustc_ast.

nnethercote · nnethercote · commit 339797e8b6fe · 2026-05-01T10:58:42.000+10:00
It currently only depends on two things:
- `rustc_ast::AttrId`: this is just a re-export of `rustc_span::AttrId`,
  so we can import the original instead.
- `rustc_ast::AttributeExt`: needed only for the `name` and `id`
  methods. We can instead pass in the `name` and `id` directly.
diff --git a/Cargo.lock b/Cargo.lock
@@ -4184,7 +4184,6 @@ dependencies = [
 name = "rustc_lint_defs"
 version = "0.0.0"
 dependencies = [
- "rustc_ast",
  "rustc_data_structures",
  "rustc_error_messages",
  "rustc_hir_id",
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
@@ -671,7 +671,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                 continue;
             }
 
-            let (level, lint_id) = match Level::from_attr(attr) {
+            let (level, lint_id) = match Level::from_attr(attr.name(), || attr.id()) {
                 None => continue,
                 // This is the only lint level with a `LintExpectationId` that can be created from
                 // an attribute.
diff --git a/compiler/rustc_lint_defs/Cargo.toml b/compiler/rustc_lint_defs/Cargo.toml
@@ -5,7 +5,6 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_hir_id = { path = "../rustc_hir_id" }
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
@@ -1,8 +1,6 @@
 use std::borrow::Cow;
 use std::fmt::Display;
 
-use rustc_ast::AttrId;
-use rustc_ast::attr::AttributeExt;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_data_structures::stable_hasher::{
     HashStable, HashStableContext, StableCompare, StableHasher, ToStableHashKey,
@@ -12,7 +10,7 @@ use rustc_hir_id::{HirId, ItemLocalId};
 use rustc_macros::{Decodable, Encodable, HashStable};
 use rustc_span::def_id::DefPathHash;
 pub use rustc_span::edition::Edition;
-use rustc_span::{Ident, Symbol, sym};
+use rustc_span::{AttrId, Ident, Symbol, sym};
 use serde::{Deserialize, Serialize};
 
 pub use self::Level::*;
@@ -238,8 +236,11 @@ impl Level {
     }
 
     /// Converts an `Attribute` to a level.
-    pub fn from_attr(attr: &impl AttributeExt) -> Option<(Self, Option<LintExpectationId>)> {
-        attr.name().and_then(|name| Self::from_symbol(name, || Some(attr.id())))
+    pub fn from_attr(
+        attr_name: Option<Symbol>,
+        attr_id: impl Fn() -> AttrId,
+    ) -> Option<(Self, Option<LintExpectationId>)> {
+        attr_name.and_then(|name| Self::from_symbol(name, || Some(attr_id())))
     }
 
     /// Converts a `Symbol` to a level.
diff --git a/compiler/rustc_mir_build/src/builder/scope.rs b/compiler/rustc_mir_build/src/builder/scope.rs
@@ -1298,7 +1298,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 break;
             }
 
-            if self.tcx.hir_attrs(id).iter().any(|attr| Level::from_attr(attr).is_some()) {
+            if self
+                .tcx
+                .hir_attrs(id)
+                .iter()
+                .any(|attr| Level::from_attr(attr.name(), || attr.id()).is_some())
+            {
                 // This is a rare case. It's for a node path that doesn't reach the root due to an
                 // intervening lint level attribute. This result doesn't get cached.
                 return id;
diff --git a/src/tools/clippy/clippy_lints/src/collapsible_if.rs b/src/tools/clippy/clippy_lints/src/collapsible_if.rs
@@ -238,7 +238,7 @@ impl CollapsibleIf {
             },
 
             [attr]
-                if matches!(Level::from_attr(attr), Some((Level::Expect, _)))
+                if matches!(Level::from_attr(attr.name(), || attr.id()), Some((Level::Expect, _)))
                     && let Some(metas) = attr.meta_item_list()
                     && let Some(MetaItemInner::MetaItem(meta_item)) = metas.first()
                     && let [tool, lint_name] = meta_item.path.segments.as_slice()
diff --git a/src/tools/clippy/clippy_lints/src/returns/needless_return.rs b/src/tools/clippy/clippy_lints/src/returns/needless_return.rs
@@ -181,7 +181,7 @@ fn check_final_expr<'tcx>(
             match cx.tcx.hir_attrs(expr.hir_id) {
                 [] => {},
                 [attr] => {
-                    if matches!(Level::from_attr(attr), Some((Level::Expect, _)))
+                    if matches!(Level::from_attr(attr.name(), || attr.id()), Some((Level::Expect, _)))
                         && let metas = attr.meta_item_list()
                         && let Some(lst) = metas
                         && let [MetaItemInner::MetaItem(meta_item), ..] = lst.as_slice()

Original file line number	Diff line number	Diff line change
`@@ -671,7 +671,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {`
`671`	`671`	`continue;`
`672`	`672`	`}`
`673`	`673`
`674`		`- let (level, lint_id) = match Level::from_attr(attr) {`
	`674`	`+ let (level, lint_id) = match Level::from_attr(attr.name(), \|\| attr.id()) {`
`675`	`675`	`None => continue,`
`676`	`676`	// This is the only lint level with a `LintExpectationId` that can be created from
`677`	`677`	`// an attribute.`