chore: get ext to compile

Author: DhairyaLGandhi

ext/SciMLBaseZygoteExt.jl

@@ -128,7 +128,7 @@ function obs_grads(VA, sym, ::Nothing, Δ)
     Zygote.nt_nothing(VA)
 end
 
-function not_obs_grads(VA::DESolution{T}, sym, not_obss_idx, i, Δ) where {T}
+function not_obs_grads(VA::DESolution, sym, not_obss_idx, i, Δ)
     Δ′ = map(enumerate(VA.u)) do (t_idx, us)
         map(enumerate(us)) do (u_idx, u)
             if u_idx in i
@@ -144,7 +144,7 @@ function not_obs_grads(VA::DESolution{T}, sym, not_obss_idx, i, Δ) where {T}
 end
 
 @adjoint function Base.getindex(
-        VA::ODESolution{T}, sym::Union{Tuple, AbstractVector}) where {T}
+        VA::ODESolution, sym::Union{Tuple, AbstractVector})
     function ODESolution_getindex_pullback(Δ)
         sym = sym isa Tuple ? collect(sym) : sym
         i = map(x -> symbolic_type(x) != NotSymbolic() ? variable_index(VA, x) : x, sym)
@@ -165,8 +165,9 @@ end
 @adjoint function Base.getindex(VA::SciMLBase.NonlinearSolution, sym)
     function NonlinearSolution_getindex_pullback(Δ)
         i = symbolic_type(sym) != NotSymbolic() ? variable_index(VA, sym) : sym
+        @show sym
         if is_observed(VA, sym)
-            f = SII.observed(VA, sym)
+            f = observed(VA, sym)
             p = parameter_values(VA)
             tunables, repack, _ = SciMLStructures.canonicalize(SciMLStructures.Tunable(), p)
             u = state_values(VA)
@@ -176,7 +177,8 @@ end
                 f.f_oop(_p, _p)
             end
             gs = back(Δ)
-            (gs[1], nothing)
+            # (gs[1], nothing)
+            ((u = gs[1], prob = (p = gs[2],)), nothing)
         elseif i === nothing
             throw(error("Zygote AD of purely-symbolic slicing for observed quantities is not yet supported. Work around this by using `A[sym,i]` to access each element sequentially in the function being differentiated."))
         else
@@ -225,6 +227,7 @@ end
         uType2
 }
     function NonlinearSolutionAdjoint(ȳ)
+        @show ȳ
         (ȳ, ntuple(_ -> nothing, length(args))...)
     end
     NonlinearSolution{T, N, uType, R, P, A, O, uType2}(u, args...), NonlinearSolutionAdjoint
@@ -233,6 +236,7 @@ end
 @adjoint function literal_getproperty(sol::SciMLBase.AbstractNoTimeSolution,
         ::Val{:u})
     function solu_adjoint(Δ)
+        @show "her"
         zerou = zero(sol.prob.u0)
         _Δ = @. ifelse(Δ === nothing, zerou, Δ)
         (build_solution(sol.prob, sol.alg, _Δ, sol.resid),)