Remove unnecessary to_ref

WardBrian · WardBrian · commit c897d3f69fff · 2025-04-10T13:24:51.000-04:00
diff --git a/stan/math/rev/constraint/simplex_constrain.hpp b/stan/math/rev/constraint/simplex_constrain.hpp
@@ -42,7 +42,7 @@ inline auto simplex_constrain(const T& y) {
   }
 
   reverse_pass_callback([arena_y, arena_x]() mutable {
-    const auto& res_val = to_ref(arena_x.val());
+    auto&& res_val = arena_x.val();
 
     // backprop for softmax
     Eigen::VectorXd x_pre_softmax_adj = -res_val * arena_x.adj().dot(res_val)
@@ -85,7 +85,7 @@ inline auto simplex_constrain(const T& y, scalar_type_t<T>& lp) {
   }
 
   reverse_pass_callback([arena_y, arena_x, lp]() mutable {
-    const auto& res_val = to_ref(arena_x.val());
+    auto&& res_val = arena_x.val();
 
     // backprop for log jacobian contribution to log density
     arena_x.adj().array() += lp.adj() / res_val.array();

Original file line number	Diff line number	Diff line change
`@@ -42,7 +42,7 @@ inline auto simplex_constrain(const T& y) {`
`42`	`42`	`}`
`43`	`43`
`44`	`44`	`reverse_pass_callback([arena_y, arena_x]() mutable {`
`45`		`- const auto& res_val = to_ref(arena_x.val());`
	`45`	`+ auto&& res_val = arena_x.val();`
`46`	`46`
`47`	`47`	`// backprop for softmax`
`48`	`48`	`Eigen::VectorXd x_pre_softmax_adj = -res_val * arena_x.adj().dot(res_val)`
`@@ -85,7 +85,7 @@ inline auto simplex_constrain(const T& y, scalar_type_t<T>& lp) {`
`85`	`85`	`}`
`86`	`86`
`87`	`87`	`reverse_pass_callback([arena_y, arena_x, lp]() mutable {`
`88`		`- const auto& res_val = to_ref(arena_x.val());`
	`88`	`+ auto&& res_val = arena_x.val();`
`89`	`89`
`90`	`90`	`// backprop for log jacobian contribution to log density`
`91`	`91`	`arena_x.adj().array() += lp.adj() / res_val.array();`