fix!: require explicit independent variable for ODESystem

Author: AayushSabharwal

src/ModelingToolkit.jl

@@ -192,7 +192,7 @@ const D = Differential(t)
 PrecompileTools.@compile_workload begin
     using ModelingToolkit
     @variables x(ModelingToolkit.t_nounits)
-    @named sys = ODESystem([ModelingToolkit.D_nounits(x) ~ -x])
+    @named sys = ODESystem([ModelingToolkit.D_nounits(x) ~ -x], ModelingToolkit.t_nounits)
     prob = ODEProblem(structural_simplify(sys), [x => 30.0], (0, 100), [], jac = true)
 end
 

src/systems/diffeqs/odesystem.jl

@@ -230,7 +230,7 @@ function ODESystem(deqs::AbstractVector{<:Equation}, iv, dvs, ps;
         metadata, gui_metadata, checks = checks)
 end
 
-function ODESystem(eqs, iv = nothing; kwargs...)
+function ODESystem(eqs, iv; kwargs...)
     eqs = scalarize(eqs)
     # NOTE: this assumes that the order of algebraic equations doesn't matter
     diffvars = OrderedSet()

src/systems/systems.jl

@@ -1,4 +1,4 @@
-function System(eqs::AbstractVector{<:Equation}, iv = nothing, args...; name = nothing,
+function System(eqs::AbstractVector{<:Equation}, iv, args...; name = nothing,
         kw...)
     ODESystem(eqs, iv, args...; name, kw..., checks = false)
 end