Auto merge of #119251 - Enselic:rustc_lint-query-stability, r=cjgillot

rustc_lint: Enforce `rustc::potential_query_instability` lint

Stop allowing `rustc::potential_query_instability` on all of `rustc_lint` and instead allow it on a case-by-case basis if it is safe to do so. In this particular crate, all lints were safe to allow.

Part of https://github.com/rust-lang/rust/issues/84447 which is E-help-wanted.

8 files changed, 36 insertions, 24 deletions

diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index c226b2d41bd..49431fb7b3f 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -3,7 +3,7 @@ use crate::{
     CodeSuggestion, DiagnosticBuilder, DiagnosticMessage, EmissionGuarantee, Level, MultiSpan,
     SubdiagnosticMessage, Substitution, SubstitutionPart, SuggestionStyle,
 };
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_error_messages::fluent_value_from_str_list_sep_by_and;
 use rustc_error_messages::FluentValue;
 use rustc_lint_defs::{Applicability, LintExpectationId};
@@ -259,7 +259,7 @@ impl Diagnostic {
 
     pub(crate) fn update_unstable_expectation_id(
         &mut self,
-        unstable_to_stable: &FxHashMap<LintExpectationId, LintExpectationId>,
+        unstable_to_stable: &FxIndexMap<LintExpectationId, LintExpectationId>,
     ) {
         if let Level::Expect(expectation_id) | Level::Warning(Some(expectation_id)) =
             &mut self.level
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index e436591fdd9..e9507dcfed7 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -55,7 +55,7 @@ pub use termcolor::{Color, ColorSpec, WriteColor};
 use crate::diagnostic_impls::{DelayedAtWithNewline, DelayedAtWithoutNewline};
 use emitter::{is_case_difference, DynEmitter, Emitter, EmitterWriter};
 use registry::Registry;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
+use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::stable_hasher::{Hash128, StableHasher};
 use rustc_data_structures::sync::{Lock, Lrc};
 use rustc_data_structures::AtomicRef;
@@ -1318,7 +1318,7 @@ impl DiagCtxt {
 
     pub fn update_unstable_expectation_id(
         &self,
-        unstable_to_stable: &FxHashMap<LintExpectationId, LintExpectationId>,
+        unstable_to_stable: &FxIndexMap<LintExpectationId, LintExpectationId>,
     ) {
         let mut inner = self.inner.borrow_mut();
         let diags = std::mem::take(&mut inner.unstable_expect_diagnostics);
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index 88a02917f36..d0fd019a8b1 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -430,6 +430,8 @@ impl LintStore {
         // Note: find_best_match_for_name depends on the sort order of its input vector.
         // To ensure deterministic output, sort elements of the lint_groups hash map.
         // Also, never suggest deprecated lint groups.
+        // We will soon sort, so the initial order does not matter.
+        #[allow(rustc::potential_query_instability)]
         let mut groups: Vec<_> = self
             .lint_groups
             .iter()
diff --git a/compiler/rustc_lint/src/context/diagnostics.rs b/compiler/rustc_lint/src/context/diagnostics.rs
index cfb0dff31f6..75756c6946a 100644
--- a/compiler/rustc_lint/src/context/diagnostics.rs
+++ b/compiler/rustc_lint/src/context/diagnostics.rs
@@ -197,6 +197,8 @@ pub(super) fn builtin(
                 if let Some(ExpectedValues::Some(best_match_values)) =
                     sess.parse_sess.check_config.expecteds.get(&best_match)
                 {
+                    // We will soon sort, so the initial order does not matter.
+                    #[allow(rustc::potential_query_instability)]
                     let mut possibilities =
                         best_match_values.iter().flatten().map(Symbol::as_str).collect::<Vec<_>>();
                     possibilities.sort();
@@ -298,6 +300,9 @@ pub(super) fn builtin(
                 );
             };
             let mut have_none_possibility = false;
+            // We later sort possibilities if it is not empty, so the
+            // order here does not matter.
+            #[allow(rustc::potential_query_instability)]
             let possibilities: Vec<Symbol> = values
                 .iter()
                 .inspect(|a| have_none_possibility |= a.is_none())
diff --git a/compiler/rustc_lint/src/levels.rs b/compiler/rustc_lint/src/levels.rs
index c229728cb79..5950bc76ade 100644
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@@ -15,7 +15,7 @@ use crate::{
 };
 use rustc_ast as ast;
 use rustc_ast_pretty::pprust;
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::{DecorateLint, DiagnosticBuilder, DiagnosticMessage, MultiSpan};
 use rustc_feature::{Features, GateIssue};
 use rustc_hir as hir;
@@ -73,7 +73,7 @@ rustc_index::newtype_index! {
 struct LintSet {
     // -A,-W,-D flags, a `Symbol` for the flag itself and `Level` for which
     // flag.
-    specs: FxHashMap<LintId, LevelAndSource>,
+    specs: FxIndexMap<LintId, LevelAndSource>,
     parent: LintStackIndex,
 }
 
@@ -86,7 +86,7 @@ impl LintLevelSets {
         &self,
         lint: &'static Lint,
         idx: LintStackIndex,
-        aux: Option<&FxHashMap<LintId, LevelAndSource>>,
+        aux: Option<&FxIndexMap<LintId, LevelAndSource>>,
         sess: &Session,
     ) -> LevelAndSource {
         let lint = LintId::of(lint);
@@ -101,7 +101,7 @@ impl LintLevelSets {
         &self,
         id: LintId,
         mut idx: LintStackIndex,
-        aux: Option<&FxHashMap<LintId, LevelAndSource>>,
+        aux: Option<&FxIndexMap<LintId, LevelAndSource>>,
     ) -> (Option<Level>, LintLevelSource) {
         if let Some(specs) = aux {
             if let Some(&(level, src)) = specs.get(&id) {
@@ -132,8 +132,8 @@ fn lint_expectations(tcx: TyCtxt<'_>, (): ()) -> Vec<(LintExpectationId, LintExp
             cur: hir::CRATE_HIR_ID,
             specs: ShallowLintLevelMap::default(),
             expectations: Vec::new(),
-            unstable_to_stable_ids: FxHashMap::default(),
-            empty: FxHashMap::default(),
+            unstable_to_stable_ids: FxIndexMap::default(),
+            empty: FxIndexMap::default(),
         },
         lint_added_lints: false,
         store,
@@ -161,7 +161,7 @@ fn shallow_lint_levels_on(tcx: TyCtxt<'_>, owner: hir::OwnerId) -> ShallowLintLe
             tcx,
             cur: owner.into(),
             specs: ShallowLintLevelMap::default(),
-            empty: FxHashMap::default(),
+            empty: FxIndexMap::default(),
             attrs,
         },
         lint_added_lints: false,
@@ -209,14 +209,14 @@ pub struct TopDown {
 }
 
 pub trait LintLevelsProvider {
-    fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource>;
+    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) {}
 }
 
 impl LintLevelsProvider for TopDown {
-    fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
+    fn current_specs(&self) -> &FxIndexMap<LintId, LevelAndSource> {
         &self.sets.list[self.cur].specs
     }
 
@@ -234,12 +234,12 @@ struct LintLevelQueryMap<'tcx> {
     cur: HirId,
     specs: ShallowLintLevelMap,
     /// Empty hash map to simplify code.
-    empty: FxHashMap<LintId, LevelAndSource>,
+    empty: FxIndexMap<LintId, LevelAndSource>,
     attrs: &'tcx hir::AttributeMap<'tcx>,
 }
 
 impl LintLevelsProvider for LintLevelQueryMap<'_> {
-    fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
+    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) {
@@ -257,13 +257,13 @@ struct QueryMapExpectationsWrapper<'tcx> {
     /// Level map for `cur`.
     specs: ShallowLintLevelMap,
     expectations: Vec<(LintExpectationId, LintExpectation)>,
-    unstable_to_stable_ids: FxHashMap<LintExpectationId, LintExpectationId>,
+    unstable_to_stable_ids: FxIndexMap<LintExpectationId, LintExpectationId>,
     /// Empty hash map to simplify code.
-    empty: FxHashMap<LintId, LevelAndSource>,
+    empty: FxIndexMap<LintId, LevelAndSource>,
 }
 
 impl LintLevelsProvider for QueryMapExpectationsWrapper<'_> {
-    fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
+    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) {
@@ -486,7 +486,7 @@ impl<'s> LintLevelsBuilder<'s, TopDown> {
             .provider
             .sets
             .list
-            .push(LintSet { specs: FxHashMap::default(), parent: COMMAND_LINE });
+            .push(LintSet { specs: FxIndexMap::default(), parent: COMMAND_LINE });
         self.add_command_line();
     }
 
@@ -512,7 +512,7 @@ impl<'s> LintLevelsBuilder<'s, TopDown> {
     ) -> BuilderPush {
         let prev = self.provider.cur;
         self.provider.cur =
-            self.provider.sets.list.push(LintSet { specs: FxHashMap::default(), parent: prev });
+            self.provider.sets.list.push(LintSet { specs: FxIndexMap::default(), parent: prev });
 
         self.add(attrs, is_crate_node, source_hir_id);
 
@@ -547,7 +547,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
         self.features
     }
 
-    fn current_specs(&self) -> &FxHashMap<LintId, LevelAndSource> {
+    fn current_specs(&self) -> &FxIndexMap<LintId, LevelAndSource> {
         self.provider.current_specs()
     }
 
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 0fc24e88b3b..93904fb5c56 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -25,7 +25,6 @@
 //!
 //! This API is completely unstable and subject to change.
 
-#![allow(rustc::potential_query_instability)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
diff --git a/compiler/rustc_lint/src/non_ascii_idents.rs b/compiler/rustc_lint/src/non_ascii_idents.rs
index 4f92fcd71c6..08b2bf6af37 100644
--- a/compiler/rustc_lint/src/non_ascii_idents.rs
+++ b/compiler/rustc_lint/src/non_ascii_idents.rs
@@ -174,6 +174,8 @@ impl EarlyLintPass for NonAsciiIdents {
 
         // Sort by `Span` so that error messages make sense with respect to the
         // order of identifier locations in the code.
+        // We will soon sort, so the initial order does not matter.
+        #[allow(rustc::potential_query_instability)]
         let mut symbols: Vec<_> = symbols.iter().collect();
         symbols.sort_by_key(|k| k.1);
 
@@ -287,6 +289,8 @@ impl EarlyLintPass for NonAsciiIdents {
             }
 
             if has_suspicious {
+                // The end result is put in `lint_reports` which is sorted.
+                #[allow(rustc::potential_query_instability)]
                 let verified_augmented_script_sets = script_states
                     .iter()
                     .flat_map(|(k, v)| match v {
@@ -299,6 +303,8 @@ impl EarlyLintPass for NonAsciiIdents {
                 let mut lint_reports: BTreeMap<(Span, Vec<char>), AugmentedScriptSet> =
                     BTreeMap::new();
 
+                // The end result is put in `lint_reports` which is sorted.
+                #[allow(rustc::potential_query_instability)]
                 'outerloop: for (augment_script_set, usage) in script_states {
                     let ScriptSetUsage::Suspicious(mut ch_list, sp) = usage else { continue };
 
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index d34d9160d55..ae432a04065 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -1,6 +1,6 @@
 use std::cmp;
 
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_errors::{Diagnostic, DiagnosticBuilder, DiagnosticId, DiagnosticMessage, MultiSpan};
 use rustc_hir::{HirId, ItemLocalId};
@@ -61,7 +61,7 @@ pub type LevelAndSource = (Level, LintLevelSource);
 /// by the attributes for *a single HirId*.
 #[derive(Default, Debug, HashStable)]
 pub struct ShallowLintLevelMap {
-    pub specs: SortedMap<ItemLocalId, FxHashMap<LintId, LevelAndSource>>,
+    pub specs: SortedMap<ItemLocalId, FxIndexMap<LintId, LevelAndSource>>,
 }
 
 /// From an initial level and source, verify the effect of special annotations: