From 4650d94d98a615462a27c6c099f0d2bda8cb4e86 Mon Sep 17 00:00:00 2001
From: Cheng <zcbenz@gmail.com>
Date: Thu, 21 Mar 2024 22:15:48 +0900
Subject: [PATCH] Add missing && in eval (#864)

Without the && args would be copied and perfect forwarding won't work.

To avoid eval calling itself recursively, the vector version of eval is
changed to take by value instead, which will save a copy of array when a
rvalue is passed.
---
 mlx/transforms.cpp | 6 +++---
 mlx/transforms.h   | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/mlx/transforms.cpp b/mlx/transforms.cpp
index 88581c52d..7a7a134fd 100644
--- a/mlx/transforms.cpp
+++ b/mlx/transforms.cpp
@@ -37,7 +37,7 @@ class Synchronizer : public Primitive {
 // are currently under a function transformation.
 int detail::InTracing::tracing_counter{0};
 
-void eval(const std::vector<array>& outputs) {
+void eval(std::vector<array> outputs) {
   std::function<void(const array&)> recurse;
   std::queue<array> tape;
   std::unordered_set<std::uintptr_t> cache;
@@ -52,8 +52,8 @@ void eval(const std::vector<array>& outputs) {
     }
   }
 
-  auto synchronizer =
-      array({}, bool_, std::make_unique<Synchronizer>(stream), outputs);
+  auto synchronizer = array(
+      {}, bool_, std::make_unique<Synchronizer>(stream), std::move(outputs));
 
   size_t depth_counter = 0;
   recurse = [&](const array& a) {
diff --git a/mlx/transforms.h b/mlx/transforms.h
index 95fdfcffe..c3d84287d 100644
--- a/mlx/transforms.h
+++ b/mlx/transforms.h
@@ -6,10 +6,10 @@
 
 namespace mlx::core {
 
-void eval(const std::vector<array>& outputs);
+void eval(std::vector<array> outputs);
 
 template <typename... Arrays>
-void eval(Arrays... outputs) {
+void eval(Arrays&&... outputs) {
   eval(std::vector<array>{std::forward<Arrays>(outputs)...});
 }