copy conflict fails when model has parameters

[jd-lara]

It seems that models with ParameterJuMP parameters fail to copy and throw an error. Looks like a missing method error.

julia> new_model, reference_map = JuMP.copy_conflict(HAUC.internal.optimization_container.JuMPmodel)
ERROR: MethodError: no method matching copy_extension_data(::ParameterJuMP._ParameterData, ::JuMP.Model, ::JuMP.Model)
Stacktrace:
 [1] copy_model(model::JuMP.Model; filter_constraints::JuMP.var"#76#77"{JuMP.Model})
   @ JuMP ~/.julia/packages/JuMP/Xrr7O/src/copy.jl:171
 [2] copy_conflict(model::JuMP.Model)
   @ JuMP ~/.julia/packages/JuMP/Xrr7O/src/copy.jl:257
 [3] top-level scope
   @ REPL[19]:1

[odow]

I don't think copying a model with parameters is going to work.

ParameterJuMP would need to implement

JuMP.jl/src/copy.jl

Lines 6 to 13 in 6901e8f

	"""
	copy_extension_data(data, new_model::AbstractModel, model::AbstractModel)
	Return a copy of the extension data `data` of the model `model` to the extension
	data of the new model `new_model`. A method should be added for any JuMP
	extension storing data in the `ext` field.
	"""
	function copy_extension_data end

However, we should have some fallback so this doesn't error:

copy_extension_data(data, new_model, model) = missing

[jd-lara]

@odow FWIW I wasn't actually trying to copy the model, just playing with the conflict features to debug a model.

[odow]

Copying the conflict is just copying a subset of the model, so it goes through the same system.

As a work-around, just add this to your script:

JuMP.copy_extension_data(::Any, ::Any, ::Any) = missing