Use Vec for expectations to have a constant order (RFC-2383)

compiler/rustc_lint/src/expect.rs

@@ -1,5 +1,4 @@
 use crate::builtin;
-use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::HirId;
 use rustc_middle::{lint::LintExpectation, ty::TyCtxt};
 use rustc_session::lint::LintExpectationId;
@@ -11,8 +10,7 @@ pub fn check_expectations(tcx: TyCtxt<'_>) {
     }
 
     let fulfilled_expectations = tcx.sess.diagnostic().steal_fulfilled_expectation_ids();
-    let lint_expectations: &FxHashMap<LintExpectationId, LintExpectation> =
+    let lint_expectations = &tcx.lint_levels(()).lint_expectations;
-        &tcx.lint_levels(()).lint_expectations;
 
     for (id, expectation) in lint_expectations {
         if !fulfilled_expectations.contains(id) {

compiler/rustc_lint/src/levels.rs

@@ -45,7 +45,7 @@ fn lint_levels(tcx: TyCtxt<'_>, (): ()) -> LintLevelMap {
 
 pub struct LintLevelsBuilder<'s> {
     sess: &'s Session,
-    lint_expectations: FxHashMap<LintExpectationId, LintExpectation>,
+    lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
     /// Each expectation has a stable and an unstable identifier. This map
     /// is used to map from unstable to stable [`LintExpectationId`]s.
     expectation_id_map: FxHashMap<LintExpectationId, LintExpectationId>,
@@ -355,7 +355,7 @@ impl<'s> LintLevelsBuilder<'s> {
                         }
                         if let Level::Expect(expect_id) = level {
                             self.lint_expectations
-                                .insert(expect_id, LintExpectation::new(reason, sp));
+                                .push((expect_id, LintExpectation::new(reason, sp)));
                         }
                     }
 
@@ -374,7 +374,7 @@ impl<'s> LintLevelsBuilder<'s> {
                                 }
                                 if let Level::Expect(expect_id) = level {
                                     self.lint_expectations
-                                        .insert(expect_id, LintExpectation::new(reason, sp));
+                                        .push((expect_id, LintExpectation::new(reason, sp)));
                                 }
                             }
                             Err((Some(ids), ref new_lint_name)) => {
@@ -414,7 +414,7 @@ impl<'s> LintLevelsBuilder<'s> {
                                 }
                                 if let Level::Expect(expect_id) = level {
                                     self.lint_expectations
-                                        .insert(expect_id, LintExpectation::new(reason, sp));
+                                        .push((expect_id, LintExpectation::new(reason, sp)));
                                 }
                             }
                             Err((None, _)) => {
@@ -511,7 +511,7 @@ impl<'s> LintLevelsBuilder<'s> {
                         }
                         if let Level::Expect(expect_id) = level {
                             self.lint_expectations
-                                .insert(expect_id, LintExpectation::new(reason, sp));
+                                .push((expect_id, LintExpectation::new(reason, sp)));
                         }
                     } else {
                         panic!("renamed lint does not exist: {}", new_name);

compiler/rustc_middle/src/lint.rs

@@ -159,7 +159,7 @@ pub struct LintLevelMap {
     ///
     /// The [`LintExpectationId`] is stored as a part of the [`Expect`](Level::Expect)
     /// lint level.
-    pub lint_expectations: FxHashMap<LintExpectationId, LintExpectation>,
+    pub lint_expectations: Vec<(LintExpectationId, LintExpectation)>,
     pub sets: LintLevelSets,
     pub id_to_set: FxHashMap<HirId, LintStackIndex>,
 }

src/test/ui/lint/rfc-2383-lint-reason/expect_multiple_lints.stderr

@@ -7,13 +7,25 @@ LL | #[expect(unused_variables, unused_mut, while_true)]
    = note: `#[warn(unfulfilled_lint_expectations)]` on by default
 
 warning: this lint expectation is unfulfilled
-  --> $DIR/expect_multiple_lints.rs:28:10
+  --> $DIR/expect_multiple_lints.rs:10:40
+   |
+LL | #[expect(unused_variables, unused_mut, while_true)]
+   |                                        ^^^^^^^^^^
+
+warning: this lint expectation is unfulfilled
+  --> $DIR/expect_multiple_lints.rs:19:10
    |
 LL | #[expect(unused_variables, unused_mut, while_true)]
    |          ^^^^^^^^^^^^^^^^
 
 warning: this lint expectation is unfulfilled
-  --> $DIR/expect_multiple_lints.rs:19:10
+  --> $DIR/expect_multiple_lints.rs:19:40
+   |
+LL | #[expect(unused_variables, unused_mut, while_true)]
+   |                                        ^^^^^^^^^^
+
+warning: this lint expectation is unfulfilled
+  --> $DIR/expect_multiple_lints.rs:28:10
    |
 LL | #[expect(unused_variables, unused_mut, while_true)]
    |          ^^^^^^^^^^^^^^^^
@@ -30,23 +42,11 @@ warning: this lint expectation is unfulfilled
 LL | #[expect(unused, while_true)]
    |                  ^^^^^^^^^^
 
-warning: this lint expectation is unfulfilled
-  --> $DIR/expect_multiple_lints.rs:19:40
-   |
-LL | #[expect(unused_variables, unused_mut, while_true)]
-   |                                        ^^^^^^^^^^
-
 warning: this lint expectation is unfulfilled
   --> $DIR/expect_multiple_lints.rs:45:10
    |
 LL | #[expect(unused, while_true)]
    |          ^^^^^^
 
-warning: this lint expectation is unfulfilled
-  --> $DIR/expect_multiple_lints.rs:10:40
-   |
-LL | #[expect(unused_variables, unused_mut, while_true)]
-   |                                        ^^^^^^^^^^
-
 warning: 8 warnings emitted
 

src/test/ui/lint/rfc-2383-lint-reason/expect_nested_lint_levels.rs

@@ -6,6 +6,7 @@
 #[expect(
     unused_mut,
     //~^ WARNING this lint expectation is unfulfilled [unfulfilled_lint_expectations]
+    //~| NOTE `#[warn(unfulfilled_lint_expectations)]` on by default
     //~| NOTE this `expect` is overridden by a `allow` attribute before the `unused_mut` lint is triggered
     reason = "this `expect` is overridden by a `allow` attribute before the `unused_mut` lint is triggered"
 )]
@@ -22,7 +23,6 @@ mod foo {
 #[expect(
     unused_mut,
     //~^ WARNING this lint expectation is unfulfilled [unfulfilled_lint_expectations]
-    //~| NOTE `#[warn(unfulfilled_lint_expectations)]` on by default
     //~| NOTE this `expect` is overridden by a `warn` attribute before the `unused_mut` lint is triggered
     reason = "this `expect` is overridden by a `warn` attribute before the `unused_mut` lint is triggered"
 )]

src/test/ui/lint/rfc-2383-lint-reason/expect_nested_lint_levels.stderr

@@ -25,23 +25,23 @@ note: the lint level is defined here
 LL |         unused_mut,
    |         ^^^^^^^^^^
 
-warning: this lint expectation is unfulfilled
-  --> $DIR/expect_nested_lint_levels.rs:23:5
-   |
-LL |     unused_mut,
-   |     ^^^^^^^^^^
-   |
-   = note: `#[warn(unfulfilled_lint_expectations)]` on by default
-   = note: this `expect` is overridden by a `warn` attribute before the `unused_mut` lint is triggered
-
 warning: this lint expectation is unfulfilled
   --> $DIR/expect_nested_lint_levels.rs:7:5
    |
 LL |     unused_mut,
    |     ^^^^^^^^^^
    |
+   = note: `#[warn(unfulfilled_lint_expectations)]` on by default
    = note: this `expect` is overridden by a `allow` attribute before the `unused_mut` lint is triggered
 
+warning: this lint expectation is unfulfilled
+  --> $DIR/expect_nested_lint_levels.rs:24:5
+   |
+LL |     unused_mut,
+   |     ^^^^^^^^^^
+   |
+   = note: this `expect` is overridden by a `warn` attribute before the `unused_mut` lint is triggered
+
 warning: this lint expectation is unfulfilled
   --> $DIR/expect_nested_lint_levels.rs:43:10
    |