From 629c26b2538547e310d8f4463fd6c9697926d17a Mon Sep 17 00:00:00 2001
From: Aayush Sabharwal <aayush.sabharwal@gmail.com>
Date: Tue, 10 Jun 2025 20:37:11 +0530
Subject: [PATCH 1/2] fix: do not unwrap initials in `initializeprobpmap`

---
 src/systems/problem_utils.jl | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/systems/problem_utils.jl b/src/systems/problem_utils.jl
index 2016b1efd8..3954d8f1e0 100644
--- a/src/systems/problem_utils.jl
+++ b/src/systems/problem_utils.jl
@@ -718,6 +718,8 @@ takes a value provider of `srcsys` and a value provider of `dstsys` and returns
 # Keyword Arguments
 - `initials`: Whether to include the `Initial` parameters of `dstsys` among the values
   to be transferred.
+- `unwrap_initials`: Whether initials in `dstsys` corresponding to unknowns in `srcsys` are
+  unwrapped.
 - `p_constructor`: The `p_constructor` argument to `process_SciMLProblem`.
 """
 function get_mtkparameters_reconstructor(srcsys::AbstractSystem, dstsys::AbstractSystem;
@@ -740,7 +742,7 @@ function get_mtkparameters_reconstructor(srcsys::AbstractSystem, dstsys::Abstrac
     end
     initials_getter = if initials && !isempty(syms[2])
         initsyms = Vector{Any}(syms[2])
-        allsyms = Set(all_symbols(srcsys))
+        allsyms = Set(variable_symbols(srcsys))
         if unwrap_initials
             for i in eachindex(initsyms)
                 sym = initsyms[i]

From 3518b395182b7cbb6997f818fa0d387e93cf8f74 Mon Sep 17 00:00:00 2001
From: Aayush Sabharwal <aayush.sabharwal@gmail.com>
Date: Tue, 10 Jun 2025 20:37:22 +0530
Subject: [PATCH 2/2] test: test that redundant observed expressions are not
 evaluated

---
 test/code_generation.jl | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/test/code_generation.jl b/test/code_generation.jl
index 15de194fd8..158ee64fbe 100644
--- a/test/code_generation.jl
+++ b/test/code_generation.jl
@@ -110,3 +110,33 @@ end
         @test val[] == 2
     end
 end
+
+@testset "Do not codegen redundant expressions" begin
+    @variables v1(t) = 1
+    @variables v2(t) [guess = 0]
+
+    mutable struct Data
+        count::Int
+    end
+    function update!(d::Data, t)
+        d.count += 1 # Count the number of times the data gets updated.
+    end
+    function (d::Data)(t)
+        update!(d, t)
+        rand(1:10)
+    end
+
+    @parameters (d1::Data)(..) = Data(0)
+    @parameters (d2::Data)(..) = Data(0)
+
+    eqs = [
+        D(v1) ~ d1(t),
+        v2 ~ d2(t) # Some of the data parameters are not actually needed to solve the system.
+    ]
+
+    @mtkbuild sys = System(eqs, t)
+    prob = ODEProblem(sys, [], (0.0, 1.0))
+    sol = solve(prob, Tsit5())
+
+    @test sol.ps[d2].count == 0
+end