POI assumes that inner VariableIndex match outer VariableIndex

Bắt đầu với trình tái hiện Julia rút gọn và lần theo trạng thái lồng nhau của CachingOptimizer, đặc biệt là VariablesContainer và các ràng buộc affine vô hướng được nêu trong báo cáo. So sánh ánh xạ biến thông qua index_map.jl và MOI_wrapper.jl của HiGHS, sau đó sử dụng lỗi kiểm thử MathOptInterface đã được báo cáo để xác minh nguyên nhân. Hoàn tất khi trình tái hiện không còn tạo ra một ràng buộc tham chiếu đến một VariableIndex bị thiếu và kiểm thử bị ảnh hưởng chạy thành công.

I still don't know where the error is.

Here is what I know:

1. The seemingly inoffensive(we know they are never inoffensive) update in POI: https://github.com/jump-dev/DiffOpt.jl/pull/316
   Led to a fail in MOI tests in DiffOpt:

test_conic_linear_VectorOfVariables_2: Error During Test at /home/runner/.julia/packages/MathOptInterface/zq9bo/src/Test/Test.jl:264
  Got exception outside of a @test
  KeyError: key MOI.VariableIndex(4) not found
  Stacktrace:
    [1] getindex(c::MathOptInterface.Utilities.CleverDicts.CleverDict{MathOptInterface.VariableIndex, MathOptInterface.VariableIndex, typeof(MathOptInterface.Utilities.CleverDicts.key_to_index), typeof(MathOptInterface.Utilities.CleverDicts.index_to_key)}, key::MathOptInterface.VariableIndex)
      @ MathOptInterface.Utilities.CleverDicts ~/.julia/packages/MathOptInterface/zq9bo/src/Utilities/CleverDicts.jl:164
    [2] getindex
      @ ~/.julia/packages/MathOptInterface/zq9bo/src/Utilities/copy/index_map.jl:64 [inlined]
    [3] _extract_row_data(dest::HiGHS.Optimizer, src::MathOptInterface.Utilities.UniversalFallback{MathOptInterface.Utilities.Model{Float64}}, mapping::MathOptInterface.Utilities.IndexMap, rowlower::Vector{Float64}, rowupper::Vector{Float64}, I::Vector{Int32}, J::Vector{Int32}, V::Vector{Float64}, ::Type{MathOptInterface.EqualTo{Float64}})
      @ HiGHS ~/.julia/packages/HiGHS/umjNf/src/MOI_wrapper.jl:2997
    [4] copy_to(dest::HiGHS.Optimizer, src::MathOptInterface.Utilities.UniversalFallback{MathOptInterface.Utilities.Model{Float64}})
      @ HiGHS ~/.julia/packages/HiGHS/umjNf/src/MOI_wrapper.jl:3065

I reduced the test to:

using Test
import MathOptInterface as MOI
import DiffOpt
import HiGHS

model = DiffOpt.diff_optimizer(HiGHS.Optimizer)

MOI.set(model, MOI.Silent(), true)

T = Float64

x = MOI.add_variable(model)
@test MOI.get(model, MOI.NumberOfVariables()) == 1

ys, vc = MOI.add_constrained_variables(model, MOI.Nonpositives(1))
y = ys[1]

@test MOI.get(model, MOI.NumberOfVariables()) == 2
z, s = MOI.add_variables(model, 2)
@test MOI.get(model, MOI.NumberOfVariables()) == 4
MOI.set(
    model,
    MOI.ObjectiveFunction{MOI.ScalarAffineFunction{T}}(),
    MOI.ScalarAffineFunction(
        MOI.ScalarAffineTerm.(T[3, 2, -4], [x, y, z]),
        T(0),
    ),
)
MOI.set(model, MOI.ObjectiveSense(), MOI.MIN_SENSE)
c = MOI.add_constraint(
    model,
    MOI.VectorAffineFunction(
        MOI.VectorAffineTerm.(
            [1, 1, 2, 3, 3],
            MOI.ScalarAffineTerm.(T[1, -1, 1, 1, 1], [x, s, y, x, z]),
        ),
        T[4, 3, -12],
    ),
    MOI.Zeros(3),
)

vz = MOI.add_constraint(model, [z], MOI.Nonnegatives(1))

vov = MOI.VectorOfVariables([s])

vs = MOI.add_constraint(model, vov, MOI.Zeros(1))

@test MOI.get(model, MOI.TerminationStatus()) == MOI.OPTIMIZE_NOT_CALLED

MOI.optimize!(model)

And the same error is trigged.

Inpective the innermost CachingOptimizer we get:

julia> model.optimizer.optimizer.optimizer.model
MOIU.CachingOptimizer
├ state: EMPTY_OPTIMIZER
├ mode: AUTOMATIC
├ model_cache: MOIU.UniversalFallback{MOIU.Model{Float64}}
│ ├ ObjectiveSense: MIN_SENSE
│ ├ ObjectiveFunctionType: MOI.ScalarAffineFunction{Float64}
│ ├ NumberOfVariables: 3
│ └ NumberOfConstraints: 5
│   ├ MOI.ScalarAffineFunction{Float64} in MOI.EqualTo{Float64}: 3
│   ├ MOI.VariableIndex in MOI.GreaterThan{Float64}: 1
│   └ MOI.VariableIndex in MOI.LessThan{Float64}: 1
└ optimizer: A HiGHS model with 0 columns and 0 rows.

Where there are only 3 variables:

julia> model.optimizer.optimizer.optimizer.model.model_cache.model.variables
MathOptInterface.Utilities.VariablesContainer{Float64}(UInt16[0x0000, 0x0004, 0x0002], [-Inf, -Inf, 0.0], [Inf, 0.0, Inf])

but the first of the affine constraints contains a 4th variable!

julia> model.optimizer.optimizer.optimizer.model.model_cache.model.constraints.moi_scalaraffinefunction.moi_equalto.constraints
MathOptInterface.Utilities.CleverDicts.CleverDict{MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}, Tuple{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.EqualTo{Float64}}, typeof(MathOptInterface.Utilities.CleverDicts.key_to_index), typeof(MathOptInterface.Utilities.CleverDicts.index_to_key)} with 3 entries:
  ConstraintIndex{ScalarAffineFunction{Float64}, EqualTo{Float64}}(1) => (0.0 + 1.0 MOI.VariableIndex(1) - 1.0 MOI.VariableIndex(4), EqualTo{Float64}(-4.0))
  ConstraintIndex{ScalarAffineFunction{Float64}, EqualTo{Float64}}(2) => (0.0 + 1.0 MOI.VariableIndex(2), EqualTo{Float64}(-3.0))
  ConstraintIndex{ScalarAffineFunction{Float64}, EqualTo{Float64}}(3) => (0.0 + 1.0 MOI.VariableIndex(1) + 1.0 MOI.VariableIndex(3), EqualTo{Float64}(12.0))