fix: fix unscalarized array passed to discrete_parameters

Author: AayushSabharwal

src/systems/callbacks.jl

@@ -904,7 +904,11 @@ function compile_equational_affect(
             obseqs, Dict([p => unPre(p) for p in parameters(affsys)]))
         rhss = map(x -> x.rhs, update_eqs)
         lhss = map(x -> x.lhs, update_eqs)
-        is_p = [lhs in Set(ps_to_update) for lhs in lhss]
+        update_ps_set = Set(ps_to_update)
+        is_p = map(lhss) do lhs
+            lhs in update_ps_set || iscall(lhs) && operation(lhs) === getindex &&
+            arguments(lhs)[1] in update_ps_set
+        end
         is_u = [lhs in Set(dvs_to_update) for lhs in lhss]
         dvs = unknowns(sys)
         ps = parameters(sys)

test/symbolic_events.jl

@@ -1471,3 +1471,19 @@ end
     sol = solve(oprob)
     @test sol[p] ≈ [[1.0, 2.0], [0.0, 0.0]]
 end
+
+@testset "Issue#2990: Unscalarized array passed to `discrete_parameters` of symbolic affect" begin
+    @parameters p(t)[1:2] d
+    @variables X(t) Y(t)
+    eqs = [
+        D(X) ~ p[1] - d*X,
+        D(Y) ~ p[2] - d*Y
+    ]
+    devent = SymbolicDiscreteCallback([1.0] => [p ~ zeros(2)]; discrete_parameters = [p])
+    @mtkcompile sys = System(eqs, t; discrete_events = devent)
+
+    sim_cond = [X => 1.0, Y => 2.0, p => [1.0, 2.0], d => 1.0]
+    oprob = ODEProblem(sys, sim_cond, 2.0)
+    sol = solve(oprob)
+    @test sol[p] ≈ [[1.0, 2.0], [0.0, 0.0]]
+end