FileFormats/LP: read_from_file returns incorrect quadratic terms

[inversed-ru]

I've been experimenting with JuMP using QPLIB instances and discovered that the known optima evaluate to incorrect objective values. It turns out that the off-diagonal quadratic terms are inflated by a factor of 2 when reading a model from an .lp file.

Test file:

Minimize
 obj: 1.0 b2 + 1.0 b3 + [ 1.0 b2 * b3 + 1.0 b2^2 ]/2

Binary
 b2 b3

End

Reading from JuMP:

julia> model = read_from_file("test.lp")
       JuMP.objective_function(model)
b2*b3 + 0.5 b2² + b2 + b3

Reading from MOI:

julia> filename = "test.lp"
       src = MOI.FileFormats.Model(; format = MOI.FileFormats.FORMAT_AUTOMATIC, filename = filename)
       MOI.read_from_file(src, filename)
       src.objective.scalar_quadratic
0.0 + 1.0 MOI.VariableIndex(1) + 1.0 MOI.VariableIndex(2) + 1.0 MOI.VariableIndex(1)*MOI.VariableIndex(2) + 0.5 MOI.VariableIndex(1)²

[odow]

Ooops. Fix is here: #2182

[inversed-ru]

I'm still getting incorrect QPLIB results. Newlines somehow affect the term coefficients.
Loaded correctly:

Minimize
 obj: [ 1.0 x2^2 + 1.0 x2 * x3 + 1.0 x2 * x4 ]/2
End

julia> JuMP.objective_function(model)
0.5 x2² + 0.5 x2*x3 + 0.5 x2*x4

Loaded incorrectly:

Minimize
 obj: [ 1.0 x2^2 + 1.0 x2 * x3 
 + 1.0 x2 * x4 ]/2
End

julia> JuMP.objective_function(model)
0.5 x2² + x2*x3 + 0.5 x2*x4

[odow]

I hate LP files