simplify dynamic_rule to not directly access nested function f

Author: oameye

src/core_systems/continuous_time_ode.jl

@@ -150,15 +150,7 @@ function SciMLBase.reinit!(ds::ContinuousTimeDynamicalSystem, u::AbstractArray =
 end
 
 # `DEIntegrator` stuff
-function dynamic_rule(integ::DEIntegrator)
-    # with remake it can happen that we have nested SDEFunctions
-    # sciml integrator deals with this internally well
-    f = integ.f
-    while hasfield(typeof(f), :f)
-        f = f.f
-    end
-    return f
-end
+dynamic_rule(integ::DEIntegrator) = integ.f.f
 current_parameters(integ::DEIntegrator) = integ.p
 initial_state(integ::DEIntegrator) = integ.sol.prob.u0
 current_state(ds::CoupledODEs) = current_state(ds.integ)

test/stochastic.jl

@@ -81,12 +81,12 @@ end
 
     # CoupledODEs creation
     ds = CoupledODEs(lorenz_oop)
-    @test dynamic_rule(ds) == lorenz_rule
+    @test dynamic_rule(ds).f == lorenz_rule
     @test ds.integ.alg isa Tsit5
     test_dynamical_system(ds, u0, p0; idt = false, iip = false)
     # and back
     sde = CoupledSDEs(ds, p0)
-    @test dynamic_rule(sde) == lorenz_rule
+    @test dynamic_rule(sde).f.f == lorenz_rule
     @test sde.integ.alg isa SOSRA
 end