Merge pull request #3184 from AayushSabharwal/as/complete-again

fix: `complete` with `split = false` removes the index cache

Author: ChrisRackauckas

src/systems/abstractsystem.jl

@@ -985,6 +985,8 @@ function complete(sys::AbstractSystem; split = true, flatten = true)
             end
             @set! sys.ps = ordered_ps
         end
+    elseif has_index_cache(sys)
+        @set! sys.index_cache = nothing
     end
     if isdefined(sys, :initializesystem) && get_initializesystem(sys) !== nothing
         @set! sys.initializesystem = complete(get_initializesystem(sys); split)
@@ -3001,8 +3003,8 @@ By default, the resulting system inherits `sys`'s name and description.
 See also [`compose`](@ref).
 """
 function extend(sys::AbstractSystem, basesys::AbstractSystem;
-    name::Symbol = nameof(sys), description = description(sys),
-    gui_metadata = get_gui_metadata(sys))
+        name::Symbol = nameof(sys), description = description(sys),
+        gui_metadata = get_gui_metadata(sys))
     T = SciMLBase.parameterless_type(basesys)
     ivs = independent_variables(basesys)
     if !(sys isa T)

test/odesystem.jl

@@ -1495,3 +1495,12 @@ end
     sys2 = complete(sys)
     @test length(equations(sys2)) == total_eqs
 end
+
+@testset "`complete` with `split = false` removes the index cache" begin
+    @variables x(t)
+    @parameters p
+    @mtkbuild sys = ODESystem(D(x) ~ p * t, t)
+    @test ModelingToolkit.get_index_cache(sys) !== nothing
+    sys2 = complete(sys; split = false)
+    @test ModelingToolkit.get_index_cache(sys2) === nothing
+end