[FileFormats.MPS] fix reading models with extra ROWS fields (#2793)

Author: odow

src/FileFormats/MPS/MPS.jl

@@ -1435,8 +1435,15 @@ end
 # ==============================================================================
 
 function parse_rows_line(data::TempMPSModel{T}, items::Vector{String}) where {T}
-    if length(items) != 2
+    if length(items) < 2
         error("Malformed ROWS line: $(join(items, " "))")
+    elseif length(items) > 2
+        # We could throw an error here, but it seems like other solvers just
+        # happily ignore the extra fields.
+        #
+        # See https://github.com/jump-dev/MathOptInterface.jl/issues/2792
+        #
+        # Oscar dislikes the poorly standardized nature of MPS.
     end
     sense, name = Sense(items[1]), items[2]
     if haskey(data.name_to_row, name)

test/FileFormats/MPS/MPS.jl

@@ -88,6 +88,7 @@ function test_failing_models()
             joinpath(@__DIR__, "failing_models", filename),
         )
     end
+    return
 end
 
 function test_empty_row_name()
@@ -1675,6 +1676,33 @@ function test_duplicate_coefficient()
     return
 end
 
+function test_issue_2792()
+    src = """
+    NAME
+    ROWS
+     N  OBJ       \$t3       0
+    COLUMNS
+        x         OBJ       2
+    RHS
+        rhs       OBJ       -3
+    BOUNDS
+     LO bounds    x         1
+     PL bounds    x
+    ENDATA
+    """
+    model = MPS.Model()
+    read!(IOBuffer(src), model)
+    dest = MOI.Utilities.Model{Float64}()
+    MOI.copy_to(dest, model)
+    @test MOI.get(dest, MOI.ListOfConstraintTypesPresent()) ==
+          [(MOI.VariableIndex, MOI.GreaterThan{Float64})]
+    x = only(MOI.get(dest, MOI.ListOfVariableIndices()))
+    F = MOI.get(dest, MOI.ObjectiveFunctionType())
+    f = MOI.get(dest, MOI.ObjectiveFunction{F}())
+    @test isapprox(f, 2.0 * x + 3.0)
+    return
+end
+
 end  # TestMPS
 
 TestMPS.runtests()

test/FileFormats/MPS/failing_models/rows_malformed.mps

@@ -1,5 +1,5 @@
 NAME
 ROWS
- N  c         d
+ N
 COLUMNS
 ENDATA