fix feasibility check

Author: joaquimg

src/iis.jl

@@ -409,7 +409,10 @@ function _feasibility_check(optimizer::Optimizer)
     if optimizer.verbose
         println("Original model primal status: $(primal_status)")
     end
-    if primal_status in (MOI.FEASIBLE_POINT, MOI.NEARLY_FEASIBLE_POINT)
+    if primal_status in (MOI.FEASIBLE_POINT, MOI.NEARLY_FEASIBLE_POINT) && !(
+        termination_status in
+        (MOI.INFEASIBLE, MOI.ALMOST_INFEASIBLE, MOI.LOCALLY_INFEASIBLE)
+    )
         return true
     end
     return false

src/solver.jl

@@ -76,7 +76,7 @@ function _elastic_filter(optimizer::Optimizer)
             #
         end
         if status in
-           (MOI.INFEASIBLE, MOI.ALMOST_INFEASIBLE, MOI.ALMOST_INFEASIBLE)
+           (MOI.INFEASIBLE, MOI.ALMOST_INFEASIBLE, MOI.LOCALLY_INFEASIBLE)
             break
         end
         for (con, func) in constraint_to_affine
@@ -129,7 +129,7 @@ function _elastic_filter(optimizer::Optimizer)
         MOI.optimize!(model)
         status = MOI.get(model, MOI.TerminationStatus())
         if status in
-           (MOI.INFEASIBLE, MOI.ALMOST_INFEASIBLE, MOI.ALMOST_INFEASIBLE)
+           (MOI.INFEASIBLE, MOI.ALMOST_INFEASIBLE, MOI.LOCALLY_INFEASIBLE)
             # this constraint is not in IIS
             # hence it remains unfixed
         elseif status in (

test/iis.jl

@@ -639,6 +639,33 @@ function test_iis_spare()
     return
 end
 
+function test_iis_binary()
+    model = Model(HiGHS.Optimizer)
+    set_silent(model)
+    @variable(model, x, Bin)
+    @constraint(model, c1, x == 1 / 2)
+    optimize!(model)
+    @show termination_status(model)
+    @show primal_status(model)
+    solver = MOCS.Optimizer()
+    MOI.set(solver, MOCS.InfeasibleModel(), JuMP.backend(model))
+    MOI.set(solver, MOCS.InnerOptimizer(), HiGHS.Optimizer)
+    MOI.compute_conflict!(solver)
+    data = solver.results
+    @test length(data) == 1
+    @test data[].irreducible
+    @test data[].metadata == MOCS.NoData()
+    @test _isequal_unordered(data[].constraints, [JuMP.index(c1)])
+    @test MOI.get(solver, MOI.ConstraintConflictStatus(), JuMP.index(c1)) ==
+          MOI.IN_CONFLICT
+    @test MOI.get(
+        solver,
+        MOI.ConstraintConflictStatus(),
+        JuMP.index(BinaryRef(x)),
+    ) == MOI.MAYBE_IN_CONFLICT
+    return
+end
+
 end # module
 
 TestIIS.runtests()