[Nonlinear] make _(Function|Subexpression)Storage immutable (#2621)

Author: odow

src/Nonlinear/ReverseAD/mathoptinterface_api.jl

@@ -153,9 +153,12 @@ function MOI.initialize(d::NLPEvaluator, requested_features::Vector{Symbol})
         #
         for k in d.subexpression_order
             len = max_chunk * length(d.subexpressions[k].nodes)
-            d.subexpressions[k].forward_storage_ϵ = zeros(len)
-            d.subexpressions[k].partials_storage_ϵ = zeros(len)
-            d.subexpressions[k].reverse_storage_ϵ = zeros(len)
+            resize!(d.subexpressions[k].forward_storage_ϵ, len)
+            fill!(d.subexpressions[k].forward_storage_ϵ, 0.0)
+            resize!(d.subexpressions[k].partials_storage_ϵ, len)
+            fill!(d.subexpressions[k].partials_storage_ϵ, 0.0)
+            resize!(d.subexpressions[k].reverse_storage_ϵ, len)
+            fill!(d.subexpressions[k].reverse_storage_ϵ, 0.0)
         end
         d.max_chunk = max_chunk
         if d.want_hess

src/Nonlinear/ReverseAD/types.jl

@@ -4,7 +4,7 @@
 # Use of this source code is governed by an MIT-style license that can be found
 # in the LICENSE.md file or at https://opensource.org/licenses/MIT.
 
-mutable struct _SubexpressionStorage
+struct _SubexpressionStorage
     nodes::Vector{Nonlinear.Node}
     adj::SparseArrays.SparseMatrixCSC{Bool,Int}
     const_values::Vector{Float64}
@@ -41,7 +41,7 @@ mutable struct _SubexpressionStorage
     end
 end
 
-mutable struct _FunctionStorage
+struct _FunctionStorage
     nodes::Vector{Nonlinear.Node}
     adj::SparseArrays.SparseMatrixCSC{Bool,Int}
     const_values::Vector{Float64}