Make ForwardDiff Optional

ext/DiffEqBaseForwardDiffExt.jl

@@ -215,8 +215,6 @@ if !hasmethod(nextfloat, Tuple{ForwardDiff.Dual})
     end
 end
 
-# bisection(f, tup::Tuple{T,T}, t_forward::Bool) where {T<:ForwardDiff.Dual} = find_zero(f, tup, Roots.AlefeldPotraShi())
-
 # Static Arrays don't support the `init` keyword argument for `sum`
 @inline __sum(f::F, args...; init, kwargs...) where {F} = sum(f, args...; init, kwargs...)
 @inline function __sum(

src/utils.jl

@@ -190,23 +190,22 @@ upconversion is not done automatically, the user is required to upconvert all in
 themselves, for an example of how this can be confusing to a user see
 https://discourse.julialang.org/t/typeerror-in-julia-turing-when-sampling-for-a-forced-differential-equation/82937
 """
-@generated function anyeltypedual(x, ::Type{Val{counter}} = Val{0}) where {counter}
-    x = x.name === Core.Compiler.typename(Type) ? x.parameters[1] : x
-    if isdualtype(x)
-        :($x)
+function anyeltypedual(x, ::Type{Val{counter}} = Val{0}) where {counter}
+    if isdualtype(typeof(x))
+        x
     elseif fieldnames(x) === ()
-        :(Any)
+        Any
     elseif counter < DUALCHECK_RECURSION_MAX
         T = diffeqmapreduce(x -> anyeltypedual(x, Val{counter + 1}), promote_dual,
             x.parameters)
         if T === Any || isconcretetype(T)
-            :($T)
+            T
         else
-            :(diffeqmapreduce(DualEltypeChecker($x, $counter + 1), promote_dual,
-                map(Val, fieldnames($(typeof(x))))))
+            diffeqmapreduce(DualEltypeChecker(typeof(x), counter + 1), promote_dual,
+                map(Val, fieldnames((typeof(x)))))
         end
     else
-        :(Any)
+        Any
     end
 end