add fwd decl of broadcast array

SteveBronder · SteveBronder · commit c29b0acc4284 · 2026-04-30T17:47:27.000-04:00
diff --git a/stan/math/fwd/functor/broadcast_array.hpp b/stan/math/fwd/functor/broadcast_array.hpp
@@ -9,7 +9,7 @@ namespace stan {
 namespace math {
 namespace internal {
 
-template <typename T>
+template <typename T, typename Enable = void>
 class broadcast_array;
 
 template <typename T>
