Merge pull request #1479 from SciML/uncache_jac

Invalidate system cache

Author: YingboMa

src/systems/abstractsystem.jl

@@ -929,6 +929,7 @@ function structural_simplify(sys::AbstractSystem; simplify=false)
     sys = tearing_reassemble(state, tearing(state), simplify=simplify)
     fullstates = [map(eq->eq.lhs, observed(sys)); states(sys)]
     @set! sys.observed = topsort_equations(observed(sys), fullstates)
+    invalidate_cache!(sys)
     return sys
 end
 

test/structural_transformation/tearing.jl

@@ -212,13 +212,18 @@ ms_eqs = []
 @named ms_model = compose(_ms_model,
                           [mass])
 
+calculate_jacobian(ms_model)
+calculate_tgrad(ms_model)
+
 # Mass starts with velocity = 1
 u0 = [
       mass.s => 0.0
       mass.v => 1.0
      ]
 
 sys = structural_simplify(ms_model)
+@test sys.jac[] === ModelingToolkit.EMPTY_JAC
+@test sys.tgrad[] === ModelingToolkit.EMPTY_TGRAD
 prob_complex = ODAEProblem(sys, u0, (0, 1.0))
 sol = solve(prob_complex, Tsit5())
 @test all(sol[mass.v] .== 1)