[FileFormats.NL] fix support for reading free constraints (#2392)

Author: odow

src/FileFormats/NL/read.jl

@@ -194,13 +194,12 @@ function _to_model(data::_CacheModel; use_nlp_block::Bool)
             lb, ub = data.constraint_lower[i], data.constraint_upper[i]
             if lb == ub
                 MOI.Nonlinear.add_constraint(nlp, expr, MOI.EqualTo(lb))
-            elseif -Inf < lb < ub < Inf
-                MOI.Nonlinear.add_constraint(nlp, expr, MOI.Interval(lb, ub))
             elseif -Inf == lb && ub < Inf
                 MOI.Nonlinear.add_constraint(nlp, expr, MOI.LessThan(ub))
-            else
-                @assert -Inf < lb && ub == Inf
+            elseif -Inf < lb && ub == Inf
                 MOI.Nonlinear.add_constraint(nlp, expr, MOI.GreaterThan(lb))
+            else
+                MOI.Nonlinear.add_constraint(nlp, expr, MOI.Interval(lb, ub))
             end
         end
         evaluator =
@@ -217,13 +216,12 @@ function _to_model(data::_CacheModel; use_nlp_block::Bool)
             f = _to_scalar_nonlinear_function(expr)::MOI.ScalarNonlinearFunction
             if lb == ub
                 MOI.add_constraint(model, f, MOI.EqualTo(lb))
-            elseif -Inf < lb < ub < Inf
-                MOI.add_constraint(model, f, MOI.Interval(lb, ub))
             elseif -Inf == lb && ub < Inf
                 MOI.add_constraint(model, f, MOI.LessThan(ub))
-            else
-                @assert -Inf < lb && ub == Inf
+            elseif -Inf < lb && ub == Inf
                 MOI.add_constraint(model, f, MOI.GreaterThan(lb))
+            else
+                MOI.add_constraint(model, f, MOI.Interval(lb, ub))
             end
         end
     end

test/FileFormats/NL/data/hs071_free_constraint.nl

@@ -0,0 +1,37 @@
+g3 1 1 0
+ 2 2 1 0 1 0
+ 2 1
+ 0 0
+ 2 0 0
+ 0 0 0 1
+ 0 0 0 0 0
+ 4 2
+ 0 0
+ 0 0 0 0 0
+C0
+o0
+v0
+v1
+C1
+o1
+v0
+v1
+O0 1
+n2
+r
+2 25
+3
+b
+3
+3
+k1
+1
+J0 2
+0 0
+1 0
+J1 2
+0 0
+1 0
+G0 2
+0 1
+1 1

test/FileFormats/NL/read.jl

@@ -638,6 +638,35 @@ function test_parse_header_integrality_both_int()
     return
 end
 
+function test_hs071_free_constraint_nlexpr()
+    model = NL.Model(; use_nlp_block = false)
+    open(joinpath(@__DIR__, "data", "hs071_free_constraint.nl"), "r") do io
+        return read!(io, model)
+    end
+    @test MOI.get(model, MOI.ListOfConstraintTypesPresent()) == [
+        (MOI.ScalarNonlinearFunction, MOI.GreaterThan{Float64}),
+        (MOI.ScalarNonlinearFunction, MOI.Interval{Float64}),
+    ]
+    for (F, S) in MOI.get(model, MOI.ListOfConstraintTypesPresent())
+        @test MOI.get(model, MOI.NumberOfConstraints{F,S}()) == 1
+    end
+    F, S = MOI.ScalarNonlinearFunction, MOI.Interval{Float64}
+    ci = first(MOI.get(model, MOI.ListOfConstraintIndices{F,S}()))
+    @test MOI.get(model, MOI.ConstraintSet(), ci) == MOI.Interval(-Inf, Inf)
+    return
+end
+
+function test_hs071_free_constraint()
+    model = NL.Model()
+    open(joinpath(@__DIR__, "data", "hs071_free_constraint.nl"), "r") do io
+        return read!(io, model)
+    end
+    block = MOI.get(model, MOI.NLPBlock())
+    @test block.constraint_bounds ==
+          [MOI.NLPBoundsPair(25.0, Inf), MOI.NLPBoundsPair(-Inf, Inf)]
+    return
+end
+
 function test_no_objective()
     model = NL.Model()
     open(joinpath(@__DIR__, "data", "hs071_no_objective.nl"), "r") do io