fix: ODESystem(::DifferentialEquation) should not mutate

NonlinearOscillations · Oct 29, 2024 · 5f86247 · 5f86247
1 parent 25e0eba
commit 5f86247
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/ext/ModelingToolkitExt.jl b/ext/ModelingToolkitExt.jl
@@ -61,6 +61,7 @@ function ModelingToolkit.ODESystem(eom::HarmonicEquation)
 end
 
 function ModelingToolkit.ODESystem(diff_eq::DifferentialEquation)
+    diff_eq = deepcopy(diff_eq)
     if !is_rearranged_standard(diff_eq)
         rearrange_standard!(diff_eq)
     end

diff --git a/test/ModelingToolkitExt.jl b/test/ModelingToolkitExt.jl
@@ -1,11 +1,9 @@
 using HarmonicBalance
 using ModelingToolkit
-
-ModelingToolkitExt = Base.get_extension(HarmonicBalance, :ModelingToolkitExt)
-
 using Test
 
 @testset "Utilities" begin
+    ModelingToolkitExt = Base.get_extension(HarmonicBalance, :ModelingToolkitExt)
     @variables α
     check = ModelingToolkitExt.declare_parameter(α)
     @test ModelingToolkit.PARAMETER ∈ values(check.val.metadata)
@@ -25,6 +23,9 @@ end
         for p in string.([α, ω, ω0, F, γ])
             @test p ∈ string.(parameters(sys))
         end
+
+        # can run a second time without error; diff_eq unmutated
+        ODESystem(diff_eq)
     end
     @testset "ODEProblem" begin
         @variables α ω ω0 F γ t x(t)