use new ODE solver changes

Author: ChrisRackauckas

Project.toml

@@ -89,7 +89,7 @@ Libdl = "1"
 LinearAlgebra = "1"
 MLStyle = "0.4.17"
 NaNMath = "0.3, 1"
-OrdinaryDiffEq = "6.72.0"
+OrdinaryDiffEq = "6.73.0"
 PrecompileTools = "1"
 RecursiveArrayTools = "2.3, 3"
 Reexport = "0.2, 1"

src/systems/diffeqs/abstractodesystem.jl

@@ -862,6 +862,8 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
     ps = full_parameters(sys)
     iv = get_iv(sys)
 
+    # TODO: Pass already computed information to varmap_to_vars call
+    # in process_u0? That would just be a small optimization
     varmap = merge(defaults, todict(u0map))
     varlist = collect(map(unwrap, dvs))
     missingvars = setdiff(varlist, collect(keys(varmap)))

test/initializationsystem.jl

@@ -332,3 +332,28 @@ p = [σ => 28.0,
 
 tspan = (0.0, 100.0)
 @test_throws ArgumentError prob=ODEProblem(sys, u0, tspan, p, jac = true)
+
+# DAE Initialization on ODE with nonlinear system for initial conditions
+# https://github.com/SciML/ModelingToolkit.jl/issues/2508
+
+using ModelingToolkit, OrdinaryDiffEq, Test
+using ModelingToolkit: t_nounits as t, D_nounits as D
+
+function System(;name)
+    vars = @variables begin
+        dx(t), [guess=0]
+        ddx(t), [guess=0]
+    end
+    eqs = [
+        D(dx) ~ ddx
+        0 ~ ddx + dx + 1
+    ]
+    return ODESystem(eqs, t, vars, []; name)
+end
+
+@mtkbuild sys = System()
+prob = ODEProblem(sys, [sys.dx => 1], (0,1)) # OK
+prob = ODEProblem(sys, [sys.ddx => -2], (0,1), guesses = [sys.dx => 1])
+sol = solve(prob, Tsit5())
+@test SciMLBase.successful_retcode(sol)
+@test sol[1] == [1.0]