Move lint level computation to rustc_middle::lint.

Author: cjgillot

compiler/rustc_lint/src/levels.rs

@@ -9,8 +9,8 @@ use rustc_hir::{intravisit, HirId};
 use rustc_index::vec::IndexVec;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::lint::{
-    reveal_actual_level, struct_lint_level, LevelAndSource, LintExpectation, LintLevelQueryMap,
-    LintLevelSource,
+    reveal_actual_level, struct_lint_level, LevelAndSource, LintExpectation, LintLevelSource,
+    ShallowLintLevelMap,
 };
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{RegisteredTools, TyCtxt};
@@ -99,7 +99,9 @@ fn lint_expectations(tcx: TyCtxt<'_>, (): ()) -> Vec<(LintExpectationId, LintExp
     let mut builder = LintLevelsBuilder {
         sess: tcx.sess,
         provider: QueryMapExpectationsWrapper {
-            map: LintLevelQueryMap { tcx, cur: hir::CRATE_HIR_ID, specs: FxHashMap::default() },
+            tcx,
+            cur: hir::CRATE_HIR_ID,
+            specs: ShallowLintLevelMap::default(),
             expectations: Vec::new(),
             unstable_to_stable_ids: FxHashMap::default(),
         },
@@ -117,12 +119,12 @@ fn lint_expectations(tcx: TyCtxt<'_>, (): ()) -> Vec<(LintExpectationId, LintExp
     builder.provider.expectations
 }
 
-fn lint_levels_on(tcx: TyCtxt<'_>, hir_id: HirId) -> FxHashMap<LintId, LevelAndSource> {
+fn shallow_lint_levels_on(tcx: TyCtxt<'_>, hir_id: HirId) -> ShallowLintLevelMap {
     let store = unerased_lint_store(tcx);
 
     let mut levels = LintLevelsBuilder {
         sess: tcx.sess,
-        provider: LintLevelQueryMap { tcx, cur: hir_id, specs: FxHashMap::default() },
+        provider: LintLevelQueryMap { tcx, cur: hir_id, specs: ShallowLintLevelMap::default() },
         warn_about_weird_lints: false,
         store,
         registered_tools: &tcx.resolutions(()).registered_tools,
@@ -143,12 +145,6 @@ pub struct TopDown {
     cur: LintStackIndex,
 }
 
-pub struct QueryMapExpectationsWrapper<'tcx> {
-    map: LintLevelQueryMap<'tcx>,
-    expectations: Vec<(LintExpectationId, LintExpectation)>,
-    unstable_to_stable_ids: FxHashMap<LintExpectationId, LintExpectationId>,
-}
-
 pub trait LintLevelsProvider {
     fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource>;
     fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource>;
@@ -170,28 +166,42 @@ impl LintLevelsProvider for TopDown {
     }
 }
 
+struct LintLevelQueryMap<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    cur: HirId,
+    specs: ShallowLintLevelMap,
+}
+
 impl LintLevelsProvider for LintLevelQueryMap<'_> {
     fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
-        &self.specs
+        &self.specs.specs
     }
     fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource> {
-        &mut self.specs
+        &mut self.specs.specs
     }
     fn get_lint_level(&self, lint: &'static Lint, _: &Session) -> LevelAndSource {
-        self.lint_level(lint)
+        self.specs.lint_level_id_at_node(self.tcx, LintId::of(lint), self.cur)
     }
 }
 
+struct QueryMapExpectationsWrapper<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    cur: HirId,
+    specs: ShallowLintLevelMap,
+    expectations: Vec<(LintExpectationId, LintExpectation)>,
+    unstable_to_stable_ids: FxHashMap<LintExpectationId, LintExpectationId>,
+}
+
 impl LintLevelsProvider for QueryMapExpectationsWrapper<'_> {
     fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
-        &self.map.specs
+        &self.specs.specs
     }
     fn current_specs_mut(&mut self) -> &mut FxHashMap<LintId, LevelAndSource> {
-        self.map.specs.clear();
-        &mut self.map.specs
+        self.specs.specs.clear();
+        &mut self.specs.specs
     }
     fn get_lint_level(&self, lint: &'static Lint, _: &Session) -> LevelAndSource {
-        self.map.lint_level(lint)
+        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") };
@@ -210,19 +220,15 @@ impl LintLevelsProvider for QueryMapExpectationsWrapper<'_> {
 
 impl<'tcx> LintLevelsBuilder<'_, QueryMapExpectationsWrapper<'tcx>> {
     fn add_id(&mut self, hir_id: HirId) {
-        self.add(
-            self.provider.map.tcx.hir().attrs(hir_id),
-            hir_id == hir::CRATE_HIR_ID,
-            Some(hir_id),
-        );
+        self.add(self.provider.tcx.hir().attrs(hir_id), hir_id == hir::CRATE_HIR_ID, Some(hir_id));
     }
 }
 
 impl<'tcx> intravisit::Visitor<'tcx> for LintLevelsBuilder<'_, QueryMapExpectationsWrapper<'tcx>> {
     type NestedFilter = nested_filter::All;
 
     fn nested_visit_map(&mut self) -> Self::Map {
-        self.provider.map.tcx.hir()
+        self.provider.tcx.hir()
     }
 
     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
@@ -941,6 +947,6 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
     }
 }
 
-pub fn provide(providers: &mut Providers) {
-    *providers = Providers { lint_levels_on, lint_expectations, ..*providers };
+pub(crate) fn provide(providers: &mut Providers) {
+    *providers = Providers { shallow_lint_levels_on, lint_expectations, ..*providers };
 }

compiler/rustc_middle/src/lint.rs

@@ -56,15 +56,27 @@ impl LintLevelSource {
 /// A tuple of a lint level and its source.
 pub type LevelAndSource = (Level, LintLevelSource);
 
+/// Return type for the `shallow_lint_levels_on` query.
+///
+/// This map represents the set of allowed lints and allowance levels given
+/// by the attributes for *a single HirId*.
+#[derive(Default, Debug, HashStable)]
+pub struct ShallowLintLevelMap {
+    pub specs: FxHashMap<LintId, LevelAndSource>,
+}
+
+/// From an initial level and source, verify the effect of special annotations:
+/// `warnings` lint level and lint caps.
+///
+/// The return of this function is suitable for diagnostics.
 pub fn reveal_actual_level(
     level: Option<Level>,
     src: &mut LintLevelSource,
     sess: &Session,
     lint: LintId,
-    get_lint_id_level: impl FnOnce(LintId) -> (Option<Level>, LintLevelSource),
+    probe_for_lint_level: impl FnOnce(LintId) -> (Option<Level>, LintLevelSource),
 ) -> Level {
-    // If `level` is none then we actually assume the default level for this
-    // lint.
+    // If `level` is none then we actually assume the default level for this lint.
     let mut level = level.unwrap_or_else(|| lint.lint.default_level(sess.edition()));
 
     // If we're about to issue a warning, check at the last minute for any
@@ -76,7 +88,7 @@ pub fn reveal_actual_level(
     // and so if we turned that into an error, it'd defeat the purpose of the
     // future compatibility warning.
     if level == Level::Warn && lint != LintId::of(FORBIDDEN_LINT_GROUPS) {
-        let (warnings_level, warnings_src) = get_lint_id_level(LintId::of(builtin::WARNINGS));
+        let (warnings_level, warnings_src) = probe_for_lint_level(LintId::of(builtin::WARNINGS));
         if let Some(configured_warning_level) = warnings_level {
             if configured_warning_level != Level::Warn {
                 level = configured_warning_level;
@@ -85,8 +97,7 @@ pub fn reveal_actual_level(
         }
     }
 
-    // Ensure that we never exceed the `--cap-lints` argument
-    // unless the source is a --force-warn
+    // Ensure that we never exceed the `--cap-lints` argument unless the source is a --force-warn
     level = if let LintLevelSource::CommandLine(_, Level::ForceWarn(_)) = src {
         level
     } else {
@@ -101,59 +112,76 @@ pub fn reveal_actual_level(
     level
 }
 
-pub struct LintLevelQueryMap<'tcx> {
-    pub tcx: TyCtxt<'tcx>,
-    pub cur: HirId,
-    pub specs: FxHashMap<LintId, LevelAndSource>,
-}
-
-impl<'tcx> LintLevelQueryMap<'tcx> {
-    pub fn lint_id_level(&self, id: LintId) -> (Option<Level>, LintLevelSource) {
-        Self::get_lint_id_level(id, self.cur, self.tcx, &self.specs)
-    }
-
-    pub fn lint_level(&self, lint: &'static Lint) -> LevelAndSource {
-        Self::get_lint_level(LintId::of(lint), self.cur, self.tcx, &self.specs)
-    }
-
-    pub fn get_lint_id_level(
+impl ShallowLintLevelMap {
+    /// Perform a deep probe in the HIR tree looking for the actual level for the lint.
+    /// This lint level is not usable for diagnostics, it needs to be corrected by
+    /// `reveal_actual_level` beforehand.
+    fn probe_for_lint_level(
+        &self,
+        tcx: TyCtxt<'_>,
         id: LintId,
-        cur: HirId,
-        tcx: TyCtxt<'tcx>,
-        specs: &FxHashMap<LintId, LevelAndSource>,
+        start: HirId,
     ) -> (Option<Level>, LintLevelSource) {
-        if let Some(&(level, src)) = specs.get(&id) {
+        if let Some(&(level, src)) = self.specs.get(&id) {
             return (Some(level), src);
         }
-        let mut cur = cur;
+        let mut cur = start;
 
         loop {
             let parent = tcx.hir().get_parent_node(cur);
             if cur == parent {
                 return (None, LintLevelSource::Default);
             }
-            let specs = tcx.lint_levels_on(parent);
-            if let Some(&(level, src)) = specs.get(&id) {
+            let specs = tcx.shallow_lint_levels_on(parent);
+            if let Some(&(level, src)) = specs.specs.get(&id) {
                 return (Some(level), src);
             }
             cur = parent
         }
     }
 
-    pub fn get_lint_level(
-        id: LintId,
+    /// Fetch and return the user-visible lint level for the given lint at the given HirId.
+    pub fn lint_level_id_at_node(
+        &self,
+        tcx: TyCtxt<'_>,
+        lint: LintId,
         cur: HirId,
-        tcx: TyCtxt<'tcx>,
-        specs: &FxHashMap<LintId, LevelAndSource>,
     ) -> (Level, LintLevelSource) {
-        let (level, mut src) = Self::get_lint_id_level(id, cur, tcx, specs);
-        let level = reveal_actual_level(level, &mut src, tcx.sess, id, |id| {
-            Self::get_lint_id_level(id, cur, tcx, specs)
+        let (level, mut src) = self.probe_for_lint_level(tcx, lint, cur);
+        let level = reveal_actual_level(level, &mut src, tcx.sess, lint, |lint| {
+            self.probe_for_lint_level(tcx, lint, cur)
         });
         (level, src)
     }
 }
 
+impl TyCtxt<'_> {
+    /// Fetch and return the user-visible lint level for the given lint at the given HirId.
+    pub fn lint_level_at_node(self, lint: &'static Lint, id: HirId) -> (Level, LintLevelSource) {
+        self.shallow_lint_levels_on(id).lint_level_id_at_node(self, LintId::of(lint), id)
+    }
+
+    /// Walks upwards from `id` to find a node which might change lint levels with attributes.
+    /// It stops at `bound` and just returns it if reached.
+    pub fn maybe_lint_level_root_bounded(self, mut id: HirId, bound: HirId) -> HirId {
+        let hir = self.hir();
+        loop {
+            if id == bound {
+                return bound;
+            }
+
+            if hir.attrs(id).iter().any(|attr| Level::from_attr(attr).is_some()) {
+                return id;
+            }
+            let next = hir.get_parent_node(id);
+            if next == id {
+                bug!("lint traversal reached the root of the crate");
+            }
+            id = next;
+        }
+    }
+}
+
 /// This struct represents a lint expectation and holds all required information
 /// to emit the `unfulfilled_lint_expectations` lint if it is unfulfilled after
 /// the `LateLintPass` has completed.

compiler/rustc_middle/src/query/mod.rs

@@ -274,7 +274,7 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    query lint_levels_on(key: HirId) -> FxHashMap<LintId, LevelAndSource> {
+    query shallow_lint_levels_on(key: HirId) -> rustc_middle::lint::ShallowLintLevelMap {
         arena_cache
         desc { |tcx| "looking up lint levels for `{}`", key }
     }

compiler/rustc_middle/src/ty/context.rs

@@ -4,7 +4,7 @@ use crate::arena::Arena;
 use crate::dep_graph::{DepGraph, DepKindStruct};
 use crate::hir::place::Place as HirPlace;
 use crate::infer::canonical::{Canonical, CanonicalVarInfo, CanonicalVarInfos};
-use crate::lint::{struct_lint_level, LintLevelSource};
+use crate::lint::struct_lint_level;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
 use crate::middle::resolve_lifetime;
 use crate::middle::stability;
@@ -57,7 +57,7 @@ use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_session::config::{CrateType, OutputFilenames};
 use rustc_session::cstore::CrateStoreDyn;
 use rustc_session::errors::TargetDataLayoutErrorsWrapper;
-use rustc_session::lint::{Level, Lint, LintId};
+use rustc_session::lint::Lint;
 use rustc_session::Limit;
 use rustc_session::Session;
 use rustc_span::def_id::{DefPathHash, StableCrateId};
@@ -2812,41 +2812,6 @@ impl<'tcx> TyCtxt<'tcx> {
         iter.intern_with(|xs| self.intern_bound_variable_kinds(xs))
     }
 
-    /// Walks upwards from `id` to find a node which might change lint levels with attributes.
-    /// It stops at `bound` and just returns it if reached.
-    pub fn maybe_lint_level_root_bounded(self, mut id: HirId, bound: HirId) -> HirId {
-        let hir = self.hir();
-        loop {
-            if id == bound {
-                return bound;
-            }
-
-            if hir.attrs(id).iter().any(|attr| Level::from_attr(attr).is_some()) {
-                return id;
-            }
-            let next = hir.get_parent_node(id);
-            if next == id {
-                bug!("lint traversal reached the root of the crate");
-            }
-            id = next;
-        }
-    }
-
-    pub fn lint_level_at_node(
-        self,
-        lint: &'static Lint,
-        id: hir::HirId,
-    ) -> (Level, LintLevelSource) {
-        let level_and_src = crate::lint::LintLevelQueryMap::get_lint_level(
-            LintId::of(lint),
-            id,
-            self,
-            self.lint_levels_on(id),
-        );
-        debug!(?id, ?level_and_src);
-        level_and_src
-    }
-
     /// Emit a lint at `span` from a lint struct (some type that implements `DecorateLint`,
     /// typically generated by `#[derive(LintDiagnostic)]`).
     pub fn emit_spanned_lint(

compiler/rustc_middle/src/ty/query.rs

@@ -1,6 +1,6 @@
 use crate::dep_graph;
 use crate::infer::canonical::{self, Canonical};
-use crate::lint::{LevelAndSource, LintExpectation};
+use crate::lint::LintExpectation;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
 use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
@@ -51,7 +51,7 @@ use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec};
 use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
 use rustc_session::cstore::{CrateDepKind, CrateSource};
 use rustc_session::cstore::{ExternCrate, ForeignModule, LinkagePreference, NativeLib};
-use rustc_session::lint::{LintExpectationId, LintId};
+use rustc_session::lint::LintExpectationId;
 use rustc_session::utils::NativeLibKind;
 use rustc_session::Limits;
 use rustc_span::symbol::Symbol;