Remove deprecated UnionAll Vararg (#1859)

* Remove deprecated UnionAll Vararg

* Replace remaining uses of Vararg in docstrings

`...` is better understood by more users and easier on the eyes

src/Enzyme.jl

@@ -170,7 +170,7 @@ end
 end
 
 """
-    autodiff(::ReverseMode, f, Activity, args::Vararg{<:Annotation, Nargs})
+    autodiff(::ReverseMode, f, Activity, args::Annotation...)
 
 Auto-differentiate function `f` at arguments `args` using reverse mode.
 
@@ -317,7 +317,7 @@ Enzyme.autodiff(ReverseWithPrimal, x->x*x, Active(3.0))
 end
 
 """
-    autodiff(mode::Mode, f, ::Type{A}, args::Vararg{Annotation, Nargs})
+    autodiff(mode::Mode, f, ::Type{A}, args::Annotation...)
 
 Like [`autodiff`](@ref) but will try to extend f to an annotation, if needed.
 """
@@ -345,7 +345,7 @@ Like [`autodiff`](@ref) but will try to guess the activity of the return value.
 end
 
 """
-    autodiff(::ForwardMode, f, Activity, args::Vararg{<:Annotation, Nargs})
+    autodiff(::ForwardMode, f, Activity, args::Annotation...)
 
 Auto-differentiate function `f` at arguments `args` using forward mode.
 
@@ -431,7 +431,7 @@ f(x) = x*x
 end
 
 """
-    autodiff_deferred(::ReverseMode, f, Activity, args::Vararg{<:Annotation, Nargs})
+    autodiff_deferred(::ReverseMode, f, Activity, args::Annotation...)
 
 Same as [`autodiff`](@ref) but uses deferred compilation to support usage in GPU
 code, as well as high-order differentiation.
@@ -472,9 +472,9 @@ code, as well as high-order differentiation.
 end
 
 """
-    autodiff_deferred(::ForwardMode, f, Activity, args::Vararg{<:Annotation, Nargs})
+    autodiff_deferred(::ForwardMode, f, Activity, args::Annotation...)
 
-Same as `autodiff(::ForwardMode, f, Activity, args)` but uses deferred compilation to support usage in GPU
+Same as `autodiff(::ForwardMode, f, Activity, args...)` but uses deferred compilation to support usage in GPU
 code, as well as high-order differentiation.
 """
 @inline function autodiff_deferred(::ForwardMode{ReturnPrimal, ABI, ErrIfFuncWritten, RuntimeActivity}, f::FA, ::Type{A}, args::Vararg{Annotation, Nargs}) where {ReturnPrimal, FA<:Annotation, A<:Annotation, Nargs, ABI, ErrIfFuncWritten, RuntimeActivity}
@@ -532,7 +532,7 @@ code, as well as high-order differentiation.
 end
 
 """
-    autodiff_thunk(::ReverseModeSplit, ftype, Activity, argtypes::Vararg{Type{<:Annotation, Nargs})
+    autodiff_thunk(::ReverseModeSplit, ftype, Activity, argtypes::Type{<:Annotation}...)
 
 Provide the split forward and reverse pass functions for annotated function type
 ftype when called with args of type `argtypes` when using reverse mode.
@@ -628,7 +628,7 @@ end
 end
 
 """
-    autodiff_thunk(::ForwardMode, ftype, Activity, argtypes::Vararg{Type{<:Annotation}, Nargs})
+    autodiff_thunk(::ForwardMode, ftype, Activity, argtypes::Type{<:Annotation}...)
 
 Provide the thunk forward mode function for annotated function type
 ftype when called with args of type `argtypes`.
@@ -798,7 +798,7 @@ import .Compiler: fspec, remove_innerty, UnknownTapeType
 end
 
 """
-    autodiff_deferred_thunk(::ReverseModeSplit, ftype, Activity, argtypes::Vararg{Type{<:Annotation}, Nargs})
+    autodiff_deferred_thunk(::ReverseModeSplit, ftype, Activity, argtypes::Type{<:Annotation}...)
 
 Provide the split forward and reverse pass functions for annotated function type
 ftype when called with args of type `argtypes` when using reverse mode.
@@ -1067,7 +1067,7 @@ grad = gradient(ReverseWithPrimal, mul, [2.0], Const([3.0]))
 ```
 
 """
-@generated function gradient(rm::ReverseMode{ReturnPrimal,RuntimeActivity,ABI,Holomorphic,ErrIfFuncWritten}, f::F, x::ty_0, args::Vararg{<:Any, N}) where {F, ty_0, ReturnPrimal, RuntimeActivity, ABI, Holomorphic, ErrIfFuncWritten, N}
+@generated function gradient(rm::ReverseMode{ReturnPrimal,RuntimeActivity,ABI,Holomorphic,ErrIfFuncWritten}, f::F, x::ty_0, args::Vararg{Any, N}) where {F, ty_0, ReturnPrimal, RuntimeActivity, ABI, Holomorphic, ErrIfFuncWritten, N}
     toemit= Expr[quote
         act_0 = !(x isa Enzyme.Const) && Compiler.active_reg_inner(Core.Typeof(x), #=seen=#(), #=world=#nothing, #=justActive=#Val(true)) == Compiler.ActiveState
     end]