Disable linearity detection for subexpression if no hessian

Author: blegat

src/Nonlinear/ReverseAD/mathoptinterface_api.jl

@@ -69,6 +69,7 @@ function MOI.initialize(d::NLPEvaluator, requested_features::Vector{Symbol})
             d.data.expressions[k],
             d.subexpression_linearity,
             moi_index_to_consecutive_index,
+            d.want_hess,
         )
         d.subexpressions[k] = subex
         d.subexpression_linearity[k] = subex.linearity

src/Nonlinear/ReverseAD/types.jl

@@ -18,12 +18,17 @@ struct _SubexpressionStorage
         expr::Nonlinear.Expression,
         subexpression_linearity,
         moi_index_to_consecutive_index,
+        want_hess::Bool,
     )
         nodes =
             _replace_moi_variables(expr.nodes, moi_index_to_consecutive_index)
         adj = Nonlinear.adjacency_matrix(nodes)
         N = length(nodes)
-        linearity = _classify_linearity(nodes, adj, subexpression_linearity)
+        linearity = if want_hess
+            _classify_linearity(nodes, adj, subexpression_linearity)[1]
+        else
+            NONLINEAR
+        end
         return new(
             nodes,
             adj,