Fix variance

This one does need fixpoint.

Author: ChayimFriedman2

src/tools/rust-analyzer/crates/hir-ty/src/variance.rs

@@ -57,11 +57,11 @@ pub(crate) fn variances_of(db: &dyn HirDatabase, def: GenericDefId) -> Option<Ar
 
 pub(crate) fn variances_of_cycle_fn(
     _db: &dyn HirDatabase,
-    result: &Option<Arc<[Variance]>>,
+    _result: &Option<Arc<[Variance]>>,
     _count: u32,
     _def: GenericDefId,
 ) -> CycleRecoveryAction<Option<Arc<[Variance]>>> {
-    CycleRecoveryAction::Fallback(result.clone())
+    CycleRecoveryAction::Iterate
 }
 
 pub(crate) fn variances_of_cycle_initial(
@@ -961,16 +961,12 @@ struct S3<T>(S<T, T>);
 
     #[test]
     fn prove_fixedpoint() {
-        // FIXME: This is wrong, this should be `FixedPoint[T: covariant, U: covariant, V: covariant]`
-        // This is a limitation of current salsa where a cycle may only set a fallback value to the
-        // query result, but we need to solve a fixpoint here. The new salsa will have this
-        // fortunately.
         check(
             r#"
 struct FixedPoint<T, U, V>(&'static FixedPoint<(), T, U>, V);
 "#,
             expect![[r#"
-                FixedPoint[T: bivariant, U: bivariant, V: bivariant]
+                FixedPoint[T: covariant, U: covariant, V: covariant]
             "#]],
         );
     }