refactor: use new reversible transformation API instead of unhack_system

Author: AayushSabharwal

lib/ModelingToolkitBase/src/systems/abstractsystem.jl

@@ -567,7 +567,7 @@ function add_initialization_parameters(sys::AbstractSystem; split = true, _unhac
     all_initialvars = Set{SymbolicT}()
     # time-independent systems don't initialize unknowns
     # but may initialize parameters using guesses for unknowns
-    _sys = _unhack_sys === nothing ? unhack_system(sys) : _unhack_sys
+    _sys = _unhack_sys === nothing ? reverse_all_default_reversible_transformations(sys) : _unhack_sys
     obs = observed(_sys)
     eqs = equations(_sys)
     for x in unknowns(_sys)
@@ -698,7 +698,7 @@ function complete(
         end
         sys = newsys
         check_no_parameter_equations(sys)
-        _unhack_sys = unhack_system(sys)
+        _unhack_sys = reverse_all_default_reversible_transformations(sys)
         if add_initial_parameters
             sys = add_initialization_parameters(sys; split, _unhack_sys)::T
         end

lib/ModelingToolkitBase/src/systems/callbacks.jl

@@ -193,7 +193,7 @@ function AffectSystem(
     union!(accessed_params, sys_params)
 
     # add scalarized unknowns to the map.
-    _obs = observed(unhack_system(affectsys))
+    _obs = observed(reverse_all_default_reversible_transformations(affectsys))
     _dvs = vcat(unknowns(affectsys), map(eq -> eq.lhs, _obs))
     _dvs = __safe_scalarize_vars(_dvs)
     _discs = __safe_scalarize_vars(discretes)
@@ -1415,7 +1415,7 @@ Base.@nospecializeinfer function compile_explicit_affect(
     ps_to_update = discretes(aff)
     dvs_to_update = setdiff(unknowns(aff), getfield.(observed(sys), :lhs))
 
-    _affsys = unhack_system(affsys)
+    _affsys = reverse_all_default_reversible_transformations(affsys)
     aff_ir_info = get_ir_info(affsys)
     aff_ir = get_irstructure(affsys)
     obseqs = Equation[]

lib/ModelingToolkitBase/src/systems/nonlinear/initializesystem.jl

@@ -55,12 +55,9 @@ function generate_initializesystem_timevarying(
         check_units = true, check_defguess = false,
         name = nameof(sys), kwargs...
     )
-    _sys = unhack_system(sys)
+    _sys = reverse_transformations_for_initialization(sys)
+    eqs = full_equations(_sys)
     trueobs = observed(_sys)
-    eqs = equations(_sys)
-    # remove any observed equations that directly or indirectly contain
-    # delayed unknowns
-    isempty(trueobs) || filter_delay_equations_variables!(sys, trueobs)
 
     # Firstly, all variables and observables are initialization unknowns
     init_vars_set = AtomicArraySet{OrderedDict{SymbolicT, Nothing}}()
@@ -226,7 +223,7 @@ function generate_initializesystem_timeindependent(
         name = nameof(sys), kwargs...
     )
     eqs = equations(sys)
-    _sys = unhack_system(sys)
+    _sys = reverse_transformations_for_initialization(sys)
     trueobs = observed(_sys)
     eqs = equations(_sys)
     # remove any observed equations that directly or indirectly contain

lib/ModelingToolkitBase/src/systems/problem_utils.jl

@@ -1833,7 +1833,7 @@ function __process_SciMLProblem(
 
     add_initials!(sys, op)
 
-    _sys = unhack_system(sys)
+    _sys = reverse_all_default_reversible_transformations(sys)
     obs = observed(_sys)
 
     guesses = operating_point_preprocess(sys, guesses; name = "guesses")
@@ -2327,7 +2327,7 @@ function get_u0(sys::AbstractSystem, varmap; kwargs...)
     op = build_operating_point(sys, varmap)
     binds = bindings(sys)
     no_override_merge_except_missing!(op, binds)
-    obs = observed(unhack_system(sys))
+    obs = observed(reverse_all_default_reversible_transformations(sys))
     add_observed_equations!(op, obs)
 
     return varmap_to_vars(op, unknowns(sys); kwargs...)
@@ -2345,7 +2345,7 @@ function get_p(sys::AbstractSystem, varmap; split = is_split(sys), kwargs...)
     binds = bindings(sys)
     no_override_merge_except_missing!(op, binds)
     add_initials!(sys, op)
-    obs = observed(unhack_system(sys))
+    obs = observed(reverse_all_default_reversible_transformations(sys))
     add_observed_equations!(op, obs)
 
     return if split

lib/ModelingToolkitBase/src/systems/systems.jl

@@ -845,7 +845,7 @@ function simplify_optimization_system(sys::System; split = true, kwargs...)
     snlsys = mtkcompile(nlsys; kwargs..., fully_determined = false)::System
     obs = observed(snlsys)
     seqs = equations(snlsys)
-    trueobs = observed(unhack_system(snlsys))
+    trueobs = observed(reverse_all_default_reversible_transformations(snlsys))
     subs = Dict{SymbolicT, SymbolicT}()
     for eq in trueobs
         subs[eq.lhs] = eq.rhs