From a566a3acc84386e4738711d27a250f63e59cbb6b Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 18 Oct 2019 08:37:27 +0200
Subject: Optimize config::required() to move default value if possible

---
 libbuild2/config/utility.txx | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'libbuild2/config/utility.txx')

diff --git a/libbuild2/config/utility.txx b/libbuild2/config/utility.txx
index 9c1455f..4c4e305 100644
--- a/libbuild2/config/utility.txx
+++ b/libbuild2/config/utility.txx
@@ -13,7 +13,7 @@ namespace build2
     pair<lookup, bool>
     required (scope& root,
               const variable& var,
-              const T& def_val,
+              T&& def_val,
               bool def_ovr,
               uint64_t save_flags)
     {
@@ -35,7 +35,7 @@ namespace build2
       //
       if (!l.defined () || (def_ovr && !l.belongs (root)))
       {
-        value& v (root.assign (var) = def_val);
+        value& v (root.assign (var) = std::forward<T> (def_val)); // VC14
         v.extra = true; // Default value flag.
 
         n = (save_flags & save_commented) == 0; // Absence means default.
-- 
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