From ba2baf20356befbba6c8d83bbb3676cfee7e146f Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Mon, 1 Nov 2021 11:32:39 +0000
Subject: [PATCH] libstdc++: Reorder constraints on std::span::span(Range&&)
 constructor.

In PR libstdc++/103013 Tim Song pointed out that we could reorder the
constraints of this constructor. That's worth doing just to reduce the
work the compiler has to do during overload resolution, even if it isn't
needed to make the code in the PR work.

libstdc++-v3/ChangeLog:

	* include/std/span (span(Range&&)): Reorder constraints.

(cherry picked from commit 09bc98098e4ad474d2ba9da52457b29bbd08874b)
---
 libstdc++-v3/include/std/span | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libstdc++-v3/include/std/span b/libstdc++-v3/include/std/span
index 4173446d1419..4b389a46af7b 100644
--- a/libstdc++-v3/include/std/span
+++ b/libstdc++-v3/include/std/span
@@ -204,11 +204,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	{ }
 
       template<typename _Range>
-	requires ranges::contiguous_range<_Range> && ranges::sized_range<_Range>
-	  && (ranges::borrowed_range<_Range> || is_const_v<element_type>)
-	  && (!__detail::__is_std_span<remove_cvref_t<_Range>>::value)
+	requires (!__detail::__is_std_span<remove_cvref_t<_Range>>::value)
 	  && (!__detail::__is_std_array<remove_cvref_t<_Range>>::value)
 	  && (!is_array_v<remove_cvref_t<_Range>>)
+	  && ranges::contiguous_range<_Range> && ranges::sized_range<_Range>
+	  && (ranges::borrowed_range<_Range> || is_const_v<element_type>)
 	  && __is_compatible_ref<ranges::range_reference_t<_Range>>::value
 	constexpr explicit(extent != dynamic_extent)
 	span(_Range&& __range)
-- 
2.47.2