Merge pull request #647 from JuliaOpt/bl/supports_constraint_no_update

🐛 Fix lazy bridge check for supported constraints

Author: blegat

src/Bridges/lazybridgeoptimizer.jl

@@ -43,7 +43,7 @@ function update_dist!(b::LazyBridgeOptimizer, constraints)
         changed = false
         for BT in b.bridgetypes
             for (F, S) in constraints
-                if MOI.supports_constraint(BT, F, S) && all(C -> MOI.supports_constraint(b, C[1], C[2]), added_constraint_types(BT, F, S))
+                if MOI.supports_constraint(BT, F, S) && all(C -> supports_constraint_no_update(b, C[1], C[2]), added_constraint_types(BT, F, S))
                     # Number of bridges needed using BT
                     dist = 1 + sum(C -> _dist(b, C[1], C[2]), added_constraint_types(BT, F, S))
                     # Is it better that what can currently be done ?
@@ -59,7 +59,7 @@ function update_dist!(b::LazyBridgeOptimizer, constraints)
 end
 
 function fill_required_constraints!(required::Set{Tuple{DataType, DataType}}, b::LazyBridgeOptimizer, F::Type{<:MOI.AbstractFunction}, S::Type{<:MOI.AbstractSet})
-    if MOI.supports_constraint(b.model, F, S) || (F, S) in keys(b.best)
+    if supports_constraint_no_update(b, F, S)
         return # The constraint is supported
     end
     if (F, S) in required
@@ -99,6 +99,11 @@ end
 function is_bridged(b::LazyBridgeOptimizer, F::Type{<:MOI.AbstractFunction}, S::Type{<:MOI.AbstractSet})
     !MOI.supports_constraint(b.model, F, S)
 end
+# Same as supports_constraint but do not trigger `update_constraint!`. This is
+# used inside `update_constraint!`.
+function supports_constraint_no_update(b::LazyBridgeOptimizer, F::Type{<:MOI.AbstractFunction}, S::Type{<:MOI.AbstractSet})
+    return MOI.supports_constraint(b.model, F, S) || (F, S) in keys(b.best)
+end
 function supports_bridging_constraint(b::LazyBridgeOptimizer, F::Type{<:MOI.AbstractFunction}, S::Type{<:MOI.AbstractSet})
     update_constraint!(b, F, S)
     return (F, S) in keys(b.best)

test/bridge.jl

@@ -167,7 +167,21 @@ MOI.supports_constraint(::ModelNoVAFinSOC{Float64},
                         ::Type{MOI.VectorAffineFunction{Float64}},
                         ::Type{MOI.SecondOrderCone}) = false
 
+# Model supporting nothing
+MOIU.@model NothingModel () () () () () () () ()
+
 @testset "LazyBridgeOptimizer" begin
+    @testset "Unsupported constraint with cycles" begin
+        # Test that `supports_constraint` works correctly when it is not
+        # supported but the bridges forms a cycle
+        mock = MOIU.MockOptimizer(NothingModel{Float64}())
+        bridged = MOIB.full_bridge_optimizer(mock, Float64)
+        @test !MOI.supports_constraint(
+            bridged, MOI.SingleVariable, MOI.GreaterThan{Float64})
+        @test !MOI.supports_constraint(
+            bridged, MOI.VectorAffineFunction{Float64}, MOI.Nonpositives)
+    end
+
     mock = MOIU.MockOptimizer(NoRSOCModel{Float64}())
     bridged_mock = MOIB.LazyBridgeOptimizer(
         mock, MOIB.AllBridgedConstraints{Float64}())