From 2b5562893880f6d2ca11a4e8898bf7a6a0d39ea5 Mon Sep 17 00:00:00 2001
From: Aayush Sabharwal <aayush.sabharwal@gmail.com>
Date: Sun, 17 Aug 2025 13:07:08 +0530
Subject: [PATCH] fix: fix callback with non-`Real` parameter and non-empty
 unknowns

---
 src/systems/callbacks.jl |  2 +-
 test/symbolic_events.jl  | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/systems/callbacks.jl b/src/systems/callbacks.jl
index a97ab2d233..f344f33d39 100644
--- a/src/systems/callbacks.jl
+++ b/src/systems/callbacks.jl
@@ -855,7 +855,7 @@ end
 function default_operating_point(affsys::AffectSystem)
     sys = system(affsys)
 
-    op = Dict(unknowns(sys) .=> 0.0)
+    op = AnyDict(unknowns(sys) .=> 0.0)
     for p in parameters(sys)
         T = symtype(p)
         if T <: Number
diff --git a/test/symbolic_events.jl b/test/symbolic_events.jl
index cf90ccd283..5f37e524e1 100644
--- a/test/symbolic_events.jl
+++ b/test/symbolic_events.jl
@@ -1421,3 +1421,22 @@ end
     @named sys = System([D(y) ~ 2x + 1, x^2 ~ 2y^3], t; discrete_events = [dev])
     sys = @test_nowarn mtkcompile(sys)
 end
+
+@testset "Non-`Real` symtype parameters in callback with unknown" begin
+    @mtkmodel MWE begin
+        @variables begin
+            x(t) = 1.0
+        end
+        @parameters begin
+            p(t)::Int = 1
+        end
+        @equations begin
+            D(x) ~ p * x
+        end
+        @discrete_events begin
+            1.0 => [x ~ p * Pre(x) * sin(x)]
+        end
+    end
+    @mtkcompile sys = MWE()
+    @test_nowarn ODEProblem(sys, [], (0.0, 1.0))
+end