Rewrite lint_expectations in a single pass.

Author: cjgillot

compiler/rustc_lint/src/expect.rs

@@ -1,20 +1,66 @@
 use crate::lints::{Expectation, ExpectationNote};
+use rustc_data_structures::fx::FxIndexMap;
+use rustc_hir::{HirId, CRATE_OWNER_ID};
+use rustc_middle::lint::LintExpectation;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::builtin::UNFULFILLED_LINT_EXPECTATIONS;
-use rustc_session::lint::LintExpectationId;
+use rustc_session::lint::{Level, LintExpectationId};
 use rustc_span::Symbol;
 
 pub(crate) fn provide(providers: &mut Providers) {
-    *providers = Providers { check_expectations, ..*providers };
+    *providers = Providers { lint_expectations, check_expectations, ..*providers };
+}
+
+fn lint_expectations(tcx: TyCtxt<'_>, (): ()) -> Vec<(LintExpectationId, LintExpectation)> {
+    let krate = tcx.hir_crate_items(());
+
+    let mut expectations = Vec::new();
+    let mut unstable_to_stable_ids = FxIndexMap::default();
+
+    let mut record_stable = |attr_id, hir_id, attr_index| {
+        let expect_id =
+            LintExpectationId::Stable { hir_id, attr_index, lint_index: None, attr_id: None };
+        unstable_to_stable_ids.entry(attr_id).or_insert(expect_id);
+    };
+    let mut push_expectations = |owner| {
+        let lints = tcx.shallow_lint_levels_on(owner);
+        if lints.expectations.is_empty() {
+            return;
+        }
+
+        expectations.extend_from_slice(&lints.expectations);
+
+        let attrs = tcx.hir_attrs(owner);
+        for &(local_id, attrs) in attrs.map.iter() {
+            // Some attributes appear multiple times in HIR, to ensure they are correctly taken
+            // into account where they matter. This means we cannot just associate the AttrId to
+            // the first HirId where we see it, but need to check it actually appears in a lint
+            // level.
+            // FIXME(cjgillot): Can this cause an attribute to appear in multiple expectation ids?
+            if !lints.specs.contains_key(&local_id) {
+                continue;
+            }
+            for (attr_index, attr) in attrs.iter().enumerate() {
+                let Some(Level::Expect(_)) = Level::from_attr(attr) else { continue };
+                record_stable(attr.id, HirId { owner, local_id }, attr_index.try_into().unwrap());
+            }
+        }
+    };
+
+    push_expectations(CRATE_OWNER_ID);
+    for owner in krate.owners() {
+        push_expectations(owner);
+    }
+
+    tcx.dcx().update_unstable_expectation_id(unstable_to_stable_ids);
+    expectations
 }
 
 fn check_expectations(tcx: TyCtxt<'_>, tool_filter: Option<Symbol>) {
     let lint_expectations = tcx.lint_expectations(());
     let fulfilled_expectations = tcx.dcx().steal_fulfilled_expectation_ids();
 
-    tracing::debug!(?lint_expectations, ?fulfilled_expectations);
-
     for (id, expectation) in lint_expectations {
         // This check will always be true, since `lint_expectations` only
         // holds stable ids

compiler/rustc_lint/src/levels.rs

@@ -39,7 +39,7 @@ use rustc_session::lint::{
 };
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Symbol};
-use rustc_span::{AttrId, Span, DUMMY_SP};
+use rustc_span::{Span, DUMMY_SP};
 use tracing::{debug, instrument};
 
 use crate::errors::{
@@ -123,34 +123,6 @@ impl LintLevelSets {
     }
 }
 
-fn lint_expectations(tcx: TyCtxt<'_>, (): ()) -> Vec<(LintExpectationId, LintExpectation)> {
-    let store = unerased_lint_store(tcx.sess);
-
-    let mut builder = LintLevelsBuilder {
-        sess: tcx.sess,
-        features: tcx.features(),
-        provider: QueryMapExpectationsWrapper {
-            tcx,
-            cur: hir::CRATE_HIR_ID,
-            specs: ShallowLintLevelMap::default(),
-            expectations: Vec::new(),
-            unstable_to_stable_ids: FxIndexMap::default(),
-            empty: FxIndexMap::default(),
-        },
-        lint_added_lints: false,
-        store,
-        registered_tools: tcx.registered_tools(()),
-    };
-
-    builder.add_command_line();
-    builder.add_id(hir::CRATE_HIR_ID);
-    tcx.hir().walk_toplevel_module(&mut builder);
-
-    tcx.dcx().update_unstable_expectation_id(builder.provider.unstable_to_stable_ids);
-
-    builder.provider.expectations
-}
-
 #[instrument(level = "trace", skip(tcx), ret)]
 fn shallow_lint_levels_on(tcx: TyCtxt<'_>, owner: hir::OwnerId) -> ShallowLintLevelMap {
     let store = unerased_lint_store(tcx.sess);
@@ -215,7 +187,7 @@ pub trait LintLevelsProvider {
     fn current_specs(&self) -> &FxIndexMap<LintId, LevelAndSource>;
     fn insert(&mut self, id: LintId, lvl: LevelAndSource);
     fn get_lint_level(&self, lint: &'static Lint, sess: &Session) -> LevelAndSource;
-    fn push_expectation(&mut self, _id: LintExpectationId, _expectation: LintExpectation) {}
+    fn push_expectation(&mut self, id: LintExpectationId, expectation: LintExpectation);
 }
 
 impl LintLevelsProvider for TopDown {
@@ -230,6 +202,8 @@ impl LintLevelsProvider for TopDown {
     fn get_lint_level(&self, lint: &'static Lint, sess: &Session) -> LevelAndSource {
         self.sets.get_lint_level(lint, self.cur, Some(self.current_specs()), sess)
     }
+
+    fn push_expectation(&mut self, _: LintExpectationId, _: LintExpectation) {}
 }
 
 struct LintLevelQueryMap<'tcx> {
@@ -251,46 +225,8 @@ impl LintLevelsProvider for LintLevelQueryMap<'_> {
     fn get_lint_level(&self, lint: &'static Lint, _: &Session) -> LevelAndSource {
         self.specs.lint_level_id_at_node(self.tcx, LintId::of(lint), self.cur)
     }
-}
-
-struct QueryMapExpectationsWrapper<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    /// HirId of the currently investigated element.
-    cur: HirId,
-    /// Level map for `cur`.
-    specs: ShallowLintLevelMap,
-    expectations: Vec<(LintExpectationId, LintExpectation)>,
-    unstable_to_stable_ids: FxIndexMap<AttrId, LintExpectationId>,
-    /// Empty hash map to simplify code.
-    empty: FxIndexMap<LintId, LevelAndSource>,
-}
-
-impl LintLevelsProvider for QueryMapExpectationsWrapper<'_> {
-    fn current_specs(&self) -> &FxIndexMap<LintId, LevelAndSource> {
-        self.specs.specs.get(&self.cur.local_id).unwrap_or(&self.empty)
-    }
-    fn insert(&mut self, id: LintId, lvl: LevelAndSource) {
-        self.specs.specs.get_mut_or_insert_default(self.cur.local_id).insert(id, lvl);
-    }
-    fn get_lint_level(&self, lint: &'static Lint, _: &Session) -> LevelAndSource {
-        // We cannot use `tcx.lint_level_at_node` because we want to know in which order the
-        // attributes have been inserted, in particular whether an `expect` follows a `forbid`.
-        self.specs.lint_level_id_at_node(self.tcx, LintId::of(lint), self.cur)
-    }
     fn push_expectation(&mut self, id: LintExpectationId, expectation: LintExpectation) {
-        let LintExpectationId::Stable { attr_id: Some(attr_id), hir_id, attr_index, .. } = id
-        else {
-            bug!("unstable expectation id should already be mapped")
-        };
-
-        self.unstable_to_stable_ids.entry(attr_id).or_insert(LintExpectationId::Stable {
-            hir_id,
-            attr_index,
-            lint_index: None,
-            attr_id: None,
-        });
-
-        self.expectations.push((id.normalize(), expectation));
+        self.specs.expectations.push((id.normalize(), expectation))
     }
 }
 
@@ -375,80 +311,6 @@ impl<'tcx> Visitor<'tcx> for LintLevelsBuilder<'_, LintLevelQueryMap<'tcx>> {
     }
 }
 
-impl<'tcx> LintLevelsBuilder<'_, QueryMapExpectationsWrapper<'tcx>> {
-    fn add_id(&mut self, hir_id: HirId) {
-        // Change both the `HirId` and the associated specs.
-        self.provider.cur = hir_id;
-        self.provider.specs.specs.clear();
-        self.add(self.provider.tcx.hir().attrs(hir_id), hir_id == hir::CRATE_HIR_ID, Some(hir_id));
-    }
-}
-
-impl<'tcx> Visitor<'tcx> for LintLevelsBuilder<'_, QueryMapExpectationsWrapper<'tcx>> {
-    type NestedFilter = nested_filter::All;
-
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.provider.tcx.hir()
-    }
-
-    fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
-        self.add_id(param.hir_id);
-        intravisit::walk_param(self, param);
-    }
-
-    fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
-        self.add_id(it.hir_id());
-        intravisit::walk_item(self, it);
-    }
-
-    fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
-        self.add_id(it.hir_id());
-        intravisit::walk_foreign_item(self, it);
-    }
-
-    fn visit_stmt(&mut self, e: &'tcx hir::Stmt<'tcx>) {
-        // We will call `add_id` when we walk
-        // the `StmtKind`. The outer statement itself doesn't
-        // define the lint levels.
-        intravisit::walk_stmt(self, e);
-    }
-
-    fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
-        self.add_id(e.hir_id);
-        intravisit::walk_expr(self, e);
-    }
-
-    fn visit_field_def(&mut self, s: &'tcx hir::FieldDef<'tcx>) {
-        self.add_id(s.hir_id);
-        intravisit::walk_field_def(self, s);
-    }
-
-    fn visit_variant(&mut self, v: &'tcx hir::Variant<'tcx>) {
-        self.add_id(v.hir_id);
-        intravisit::walk_variant(self, v);
-    }
-
-    fn visit_local(&mut self, l: &'tcx hir::LetStmt<'tcx>) {
-        self.add_id(l.hir_id);
-        intravisit::walk_local(self, l);
-    }
-
-    fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
-        self.add_id(a.hir_id);
-        intravisit::walk_arm(self, a);
-    }
-
-    fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
-        self.add_id(trait_item.hir_id());
-        intravisit::walk_trait_item(self, trait_item);
-    }
-
-    fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
-        self.add_id(impl_item.hir_id());
-        intravisit::walk_impl_item(self, impl_item);
-    }
-}
-
 pub struct LintLevelsBuilder<'s, P> {
     sess: &'s Session,
     features: &'s Features,
@@ -1109,7 +971,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
 }
 
 pub(crate) fn provide(providers: &mut Providers) {
-    *providers = Providers { shallow_lint_levels_on, lint_expectations, ..*providers };
+    *providers = Providers { shallow_lint_levels_on, ..*providers };
 }
 
 pub fn parse_lint_and_tool_name(lint_name: &str) -> (Option<Symbol>, &str) {

compiler/rustc_middle/src/lint.rs

@@ -7,7 +7,7 @@ use rustc_hir::{HirId, ItemLocalId};
 use rustc_macros::HashStable;
 use rustc_session::lint::{
     builtin::{self, FORBIDDEN_LINT_GROUPS},
-    FutureIncompatibilityReason, Level, Lint, LintId,
+    FutureIncompatibilityReason, Level, Lint, LintExpectationId, LintId,
 };
 use rustc_session::Session;
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -63,6 +63,7 @@ pub type LevelAndSource = (Level, LintLevelSource);
 /// by the attributes for *a single HirId*.
 #[derive(Default, Debug, HashStable)]
 pub struct ShallowLintLevelMap {
+    pub expectations: Vec<(LintExpectationId, LintExpectation)>,
     pub specs: SortedMap<ItemLocalId, FxIndexMap<LintId, LevelAndSource>>,
 }
 

tests/ui/error-codes/E0602.stderr

@@ -13,11 +13,6 @@ warning[E0602]: unknown lint: `bogus`
    = note: requested on the command line with `-D bogus`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-warning[E0602]: unknown lint: `bogus`
-   |
-   = note: requested on the command line with `-D bogus`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-warning: 4 warnings emitted
+warning: 3 warnings emitted
 
 For more information about this error, try `rustc --explain E0602`.

tests/ui/lint/cli-unknown-force-warn.stderr

@@ -13,11 +13,6 @@ warning[E0602]: unknown lint: `foo_qux`
    = note: requested on the command line with `--force-warn foo_qux`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-warning[E0602]: unknown lint: `foo_qux`
-   |
-   = note: requested on the command line with `--force-warn foo_qux`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-warning: 4 warnings emitted
+warning: 3 warnings emitted
 
 For more information about this error, try `rustc --explain E0602`.

tests/ui/lint/lint-removed-cmdline-deny.stderr

@@ -26,10 +26,5 @@ LL | #[deny(warnings)]
    |        ^^^^^^^^
    = note: `#[deny(unused_variables)]` implied by `#[deny(warnings)]`
 
-error: lint `raw_pointer_derive` has been removed: using derive with raw pointers is ok
-   |
-   = note: requested on the command line with `-D raw_pointer_derive`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 

tests/ui/lint/lint-removed-cmdline.stderr

@@ -26,10 +26,5 @@ LL | #[deny(warnings)]
    |        ^^^^^^^^
    = note: `#[deny(unused_variables)]` implied by `#[deny(warnings)]`
 
-warning: lint `raw_pointer_derive` has been removed: using derive with raw pointers is ok
-   |
-   = note: requested on the command line with `-D raw_pointer_derive`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 1 previous error; 4 warnings emitted
+error: aborting due to 1 previous error; 3 warnings emitted
 

tests/ui/lint/lint-renamed-cmdline-deny.stderr

@@ -29,11 +29,5 @@ LL | #[deny(unused)]
    |        ^^^^^^
    = note: `#[deny(unused_variables)]` implied by `#[deny(unused)]`
 
-error: lint `bare_trait_object` has been renamed to `bare_trait_objects`
-   |
-   = help: use the new name `bare_trait_objects`
-   = note: requested on the command line with `-D bare_trait_object`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 

tests/ui/lint/lint-renamed-cmdline.stderr

@@ -29,11 +29,5 @@ LL | #[deny(unused)]
    |        ^^^^^^
    = note: `#[deny(unused_variables)]` implied by `#[deny(unused)]`
 
-warning: lint `bare_trait_object` has been renamed to `bare_trait_objects`
-   |
-   = help: use the new name `bare_trait_objects`
-   = note: requested on the command line with `-D bare_trait_object`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 1 previous error; 4 warnings emitted
+error: aborting due to 1 previous error; 3 warnings emitted
 

tests/ui/lint/lint-unexported-no-mangle.stderr

@@ -45,15 +45,5 @@ LL | pub const PUB_FOO: u64 = 1;
    | |
    | help: try a static value: `pub static`
 
-warning: lint `private_no_mangle_fns` has been removed: no longer a warning, `#[no_mangle]` functions always exported
-   |
-   = note: requested on the command line with `-F private_no_mangle_fns`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-warning: lint `private_no_mangle_statics` has been removed: no longer a warning, `#[no_mangle]` statics always exported
-   |
-   = note: requested on the command line with `-F private_no_mangle_statics`
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 2 previous errors; 8 warnings emitted
+error: aborting due to 2 previous errors; 6 warnings emitted