fix fwd includes by making a separate in

Author: SteveBronder

stan/math/fwd/fun/fft.hpp

@@ -2,12 +2,12 @@
 #define STAN_MATH_FWD_FUN_FFT_HPP
 
 #include <stan/math/prim/fun/Eigen.hpp>
-#include <stan/math/prim/fun/fft.hpp>
-#include <stan/math/prim/fun/to_ref.hpp>
-#include <stan/math/prim/meta.hpp>
 #include <stan/math/fwd/core.hpp>
-#include <stan/math/fwd/fun/value_of.hpp>
 #include <stan/math/fwd/meta.hpp>
+#include <stan/math/fwd/fun/value_of.hpp>
+#include <stan/math/prim/meta.hpp>
+#include <stan/math/prim/fun/fft.hpp>
+#include <stan/math/prim/fun/to_ref.hpp>
 #include <complex>
 
 namespace stan {

stan/math/fwd/functor.hpp

@@ -2,6 +2,7 @@
 #define STAN_MATH_FWD_FUNCTOR_HPP
 
 #include <stan/math/fwd/functor/apply_scalar_unary.hpp>
+#include <stan/math/fwd/functor/broadcast_array.hpp>
 #include <stan/math/fwd/functor/gradient.hpp>
 #include <stan/math/fwd/functor/finite_diff.hpp>
 #include <stan/math/fwd/functor/hessian.hpp>

stan/math/fwd/functor/broadcast_array.hpp

@@ -0,0 +1,37 @@
+#ifndef STAN_MATH_FWD_META_BROADCAST_ARRAY_HPP
+#define STAN_MATH_FWD_META_BROADCAST_ARRAY_HPP
+
+#include <stan/math/prim/fun/Eigen.hpp>
+#include <stan/math/fwd/fun/sum.hpp>
+#include <stan/math/prim/meta.hpp>
+
+namespace stan {
+namespace math {
+namespace internal {
+
+template <typename T>
+class broadcast_array<T, require_st_fvar<T>> {
+ private:
+  std::reference_wrapper<T> prim_;
+
+ public:
+  template <typename TT>
+  explicit broadcast_array(TT&& prim) : prim_(std::forward<TT>(prim)) {}
+
+  T& operator[](int /*i*/) { return prim_.get(); }
+
+  /** \ingroup type_trait
+   * Broadcast array can be assigned a scalar or a vector. If assigned a scalar,
+   * it will be used directly. If assigned a vector, the argument will be summed
+   * first.
+   */
+  template <typename Y>
+  void operator=(const Y& m) {
+    prim_.get() = sum(m);
+  }
+};
+
+}
+}
+}
+#endif

stan/math/fwd/functor/operands_and_partials.hpp

@@ -4,14 +4,14 @@
 #include <stan/math/prim/fun/Eigen.hpp>
 #include <stan/math/prim/meta.hpp>
 #include <stan/math/prim/fun/size.hpp>
+#include <stan/math/fwd/functor/broadcast_array.hpp>
 #include <stan/math/fwd/core/fvar.hpp>
 #include <stan/math/fwd/meta.hpp>
 #include <stan/math/fwd/fun/sum.hpp>
 #include <stan/math/prim/fun/as_column_vector_or_scalar.hpp>
 #include <stan/math/prim/fun/elt_multiply.hpp>
 #include <stan/math/prim/functor/apply.hpp>
 #include <stan/math/prim/functor/for_each.hpp>
-#include <stan/math/prim/functor/broadcast_array.hpp>
 #include <stan/math/prim/functor/operands_and_partials.hpp>
 #include <vector>
 

stan/math/prim/functor/broadcast_array.hpp

@@ -2,6 +2,7 @@
 #define STAN_MATH_PRIM_META_BROADCAST_ARRAY_HPP
 
 #include <stan/math/prim/meta/is_eigen.hpp>
+#include <stan/math/prim/meta/is_var_or_arithmetic.hpp>
 #include <stan/math/prim/meta/promote_scalar_type.hpp>
 #include <stan/math/prim/meta/ref_type.hpp>
 #include <stan/math/prim/fun/Eigen.hpp>
@@ -13,8 +14,11 @@ namespace stan {
 namespace math {
 namespace internal {
 
+template <typename T, typename Enable = void>
+class broadcast_array;
+
 template <typename T>
-class broadcast_array {
+class broadcast_array<T, require_t<is_var_or_arithmetic<T>>> {
  private:
   std::reference_wrapper<T> prim_;
 

stan/math/rev/functor/partials_propagator.hpp

@@ -5,7 +5,6 @@
 #include <stan/math/rev/core/var.hpp>
 #include <stan/math/rev/core/typedefs.hpp>
 #include <stan/math/rev/functor/operands_and_partials.hpp>
-#include <stan/math/prim/functor/partials_propagator.hpp>
 #include <stan/math/prim/functor/for_each.hpp>
 #include <vector>
 #include <tuple>
@@ -15,6 +14,9 @@ namespace math {
 
 namespace internal {
 
+template <typename ReturnType, typename Enable, typename... Ops>
+class partials_propagator;
+
 /** \ingroup type_trait
  * \callergraph
  * This class builds partial derivatives with respect to a set of