Fix Constraint/Objective.SingleBridgeOptimizer with inner variable bridges

src/Bridges/Constraint/single_bridge_optimizer.jl

@@ -44,6 +44,22 @@ function MOIB.is_bridged(b::SingleBridgeOptimizer, S::Type{<:MOI.AbstractSet})
     return MOIB.supports_bridging_constrained_variable(b, S)
 end
 
+MOIB.is_bridged(::SingleBridgeOptimizer, ::MOI.VariableIndex) = false
+function MOIB.is_bridged(
+    b::SingleBridgeOptimizer,
+    ci::MOI.ConstraintIndex{MOI.SingleVariable,S},
+) where {S}
+    return MOIB.is_bridged(b, MOI.SingleVariable, S) &&
+           haskey(Constraint.bridges(b), ci)
+end
+function MOIB.is_bridged(
+    b::SingleBridgeOptimizer,
+    ci::MOI.ConstraintIndex{MOI.VectorOfVariables,S},
+) where {S}
+    return MOIB.is_bridged(b, MOI.VectorOfVariables, S) &&
+           haskey(Constraint.bridges(b), ci)
+end
+
 function MOIB.supports_bridging_constrained_variable(
     b::SingleBridgeOptimizer,
     S::Type{<:MOI.AbstractSet},

src/Bridges/Objective/single_bridge_optimizer.jl

@@ -36,6 +36,20 @@ function MOIB.is_bridged(
     return false
 end
 
+MOIB.is_bridged(::SingleBridgeOptimizer, ::MOI.VariableIndex) = false
+function MOIB.is_bridged(
+    ::SingleBridgeOptimizer,
+    ::MOI.ConstraintIndex{MOI.SingleVariable},
+)
+    return false
+end
+function MOIB.is_bridged(
+    ::SingleBridgeOptimizer,
+    ::MOI.ConstraintIndex{MOI.VectorOfVariables},
+)
+    return false
+end
+
 function MOIB.supports_bridging_objective_function(
     ::SingleBridgeOptimizer{BT},
     F::Type{<:MOI.AbstractScalarFunction},

test/Bridges/bridge_optimizer.jl

@@ -539,3 +539,52 @@ end
         @test all(vi -> !MOI.is_valid(model, vi), x)
     end
 end
+
+function test_nesting_SingleBridgeOptimizer(::Type{T}) where {T}
+    model = MOIU.Model{T}()
+    b0 = MOIB.Variable.Free{T}(model)
+    b1 = MOIB.Constraint.ScalarFunctionize{T}(b0)
+    b2 = MOIB.Constraint.VectorFunctionize{T}(b1)
+    b = MOIB.Objective.Functionize{T}(b2)
+    x = MOI.add_variable(b)
+    @test MOI.is_valid(b, x)
+    @test !MOIB.is_bridged(b, x)
+    @test MOI.is_valid(b2, x)
+    @test !MOIB.is_bridged(b2, x)
+    @test MOI.is_valid(b1, x)
+    @test !MOIB.is_bridged(b1, x)
+    @test MOI.is_valid(b0, x)
+    @test MOIB.is_bridged(b0, x)
+    @test !MOI.is_valid(model, x)
+    fx = MOI.SingleVariable(x)
+    clt = MOI.add_constraint(b, fx, MOI.LessThan(one(T)))
+    @test MOI.is_valid(b, clt)
+    @test !MOIB.is_bridged(b, clt)
+    @test MOI.is_valid(b2, clt)
+    @test !MOIB.is_bridged(b2, clt)
+    @test MOI.is_valid(b1, clt)
+    @test MOIB.is_bridged(b1, clt)
+    @test !MOI.is_valid(b0, clt)
+    @test !MOI.is_valid(model, clt)
+    cnn = MOI.add_constraint(b, MOIU.vectorize([fx]), MOI.Nonnegatives(1))
+    @test MOI.is_valid(b, cnn)
+    @test !MOIB.is_bridged(b, cnn)
+    @test MOI.is_valid(b2, cnn)
+    @test MOIB.is_bridged(b2, cnn)
+    @test !MOI.is_valid(b1, cnn)
+    @test !MOI.is_valid(b0, cnn)
+    @test !MOI.is_valid(model, cnn)
+    obj = fx
+    attr = MOI.ObjectiveFunction{typeof(obj)}()
+    MOI.set(b, attr, obj)
+    @test MOIB.is_bridged(b, attr)
+    obj = one(T) * fx
+    attr = MOI.ObjectiveFunction{typeof(obj)}()
+    MOI.set(b, attr, obj)
+    @test !MOIB.is_bridged(b, attr)
+    @test !MOIB.is_bridged(b2, attr)
+    @test !MOIB.is_bridged(b1, attr)
+    @test !MOIB.is_bridged(b0, attr)
+end
+
+test_nesting_SingleBridgeOptimizer(Float64)