From 8bdbeed1d0b00bc21a105712b1b672ebec37358e Mon Sep 17 00:00:00 2001
From: Ville Voutilainen <ville.voutilainen@gmail.com>
Date: Wed, 3 Jan 2018 22:33:10 +0200
Subject: Protect optional's deduction guide with the feature macro

* include/std/optional: Use the feature macro.

From-SVN: r256185
---
 libstdc++-v3/ChangeLog            | 5 +++++
 libstdc++-v3/include/std/optional | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index f603e316..64fa720 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,8 @@
+2018-01-03  Ville Voutilainen  <ville.voutilainen@gmail.com>
+
+	Protect optional's deduction guide with the feature macro
+	* include/std/optional: Use the feature macro.
+
 2018-01-03  Jakub Jelinek  <jakub@redhat.com>
 
 	Update copyright years.
diff --git a/libstdc++-v3/include/std/optional b/libstdc++-v3/include/std/optional
index 76b2b0e..466a11c 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -1038,7 +1038,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   /// @}
 
+#if __cpp_deduction_guides >= 201606
   template <typename _Tp> optional(_Tp) -> optional<_Tp>;
+#endif
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
-- 
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