From 4be93760d15266d80c0a3f21b8a26e0e9f585d5b Mon Sep 17 00:00:00 2001
From: Laurent Rineau <laurent.rineau@cgal.org>
Date: Tue, 26 Sep 2023 12:42:33 +0200
Subject: [PATCH] try to workaround MSVC2022 error

```
2>C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.35.32215\include\type_traits(143,19): error C2338: static_assert failed: 'Calling declval is ill-formed, see N4917 22.2.6 [declval]/2.'
2>C:\GitHub\cgal\Triangulation_3\test\Triangulation_3\cdt_3_from_off.cpp(311): message : see reference to function template instantiation 'Segment &&std::declval<Segment>(void) noexcept' being compiled
2>C:\GitHub\cgal\Triangulation_3\test\Triangulation_3\cdt_3_from_off.cpp(311,57): message : see reference to function template instantiation 'std::vector<std::vector<Point,std::allocator<Point>>,std::allocator<std::vector<Point,std::allocator<Point>>>> segment_soup_to_polylines<_Ty&>(Range_of_segments)' being compiled
```
---
 Triangulation_3/test/Triangulation_3/cdt_3_from_off.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Triangulation_3/test/Triangulation_3/cdt_3_from_off.cpp b/Triangulation_3/test/Triangulation_3/cdt_3_from_off.cpp
index 9b788e9656b..c257f714f55 100644
--- a/Triangulation_3/test/Triangulation_3/cdt_3_from_off.cpp
+++ b/Triangulation_3/test/Triangulation_3/cdt_3_from_off.cpp
@@ -157,8 +157,8 @@ int main(int argc, char* argv[])
 
 template <typename Range_of_segments>
 auto segment_soup_to_polylines(Range_of_segments&& segment_soup) {
-  using Segment = typename std::ranges::range_value_t<Range_of_segments>;
-  using Point = std::decay_t<decltype([](){ auto [a, b] = std::declval<Segment>(); return a; } ())>;
+  using Point = decltype([&](){ using std::begin; auto [a, b] = *begin(segment_soup); return a; } ());
+
   std::vector<std::vector<Point>> polylines;
 
   using Graph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, Point>;