Fix get for MOI.VariablePrimalStart and error when x is a Parameter (#…

…439)

src/MOI_wrapper.jl

@@ -630,14 +630,26 @@ function MOI.supports(
     return true
 end
 
+function MOI.get(
+    model::Optimizer,
+    attr::MOI.VariablePrimalStart,
+    vi::MOI.VariableIndex,
+)
+    if _is_parameter(vi)
+        throw(MOI.GetAttributeNotAllowed(attr, "Variable is a Parameter"))
+    end
+    MOI.throw_if_not_valid(model, vi)
+    return model.variable_primal_start[column(vi)]
+end
+
 function MOI.set(
     model::Optimizer,
-    ::MOI.VariablePrimalStart,
+    attr::MOI.VariablePrimalStart,
     vi::MOI.VariableIndex,
     value::Union{Real,Nothing},
 )
     if _is_parameter(vi)
-        return  # Do nothing
+        throw(MOI.SetAttributeNotAllowed(attr, "Variable is a Parameter"))
     end
     MOI.throw_if_not_valid(model, vi)
     model.variable_primal_start[column(vi)] = value

test/MOI_wrapper.jl

@@ -633,6 +633,26 @@ function test_nlp_model_set_set()
     return
 end
 
+function test_VariablePrimalStart()
+    attr = MOI.VariablePrimalStart()
+    model = Ipopt.Optimizer()
+    x = MOI.add_variable(model)
+    @test MOI.supports(model, attr, typeof(x))
+    @test MOI.get(model, attr, x) === nothing
+    MOI.set(model, attr, x, 1.0)
+    @test MOI.get(model, attr, x) == 1.0
+    p, _ = MOI.add_constrained_variable(model, MOI.Parameter(1.0))
+    @test_throws(
+        MOI.GetAttributeNotAllowed{typeof(attr)},
+        MOI.get(model, attr, p),
+    )
+    @test_throws(
+        MOI.SetAttributeNotAllowed{typeof(attr)},
+        MOI.set(model, attr, p, 1.0),
+    )
+    return
+end
+
 function test_manually_evaluated_primal_status()
     model = Ipopt.Optimizer()
     MOI.set(model, MOI.Silent(), true)