CGAL users discussion list

[Andrew Cunningham <>]

Hi AAron,
We use Intel Compiler 19.1 Update 4 with CGAL on both Linux (GCC 8)
and Windows ( Visual Studio 2019 16.7.5).
We needed to put the code below in the first few lines of the .cxx
files that use CGAL.

The problems are not arguably caused by "bugs" in the Intel Compiler.
I would argue it is questionable CGAL C++ headers. For example
__cpp_lib_is_swappable is a C++20 feature not a C++17 feature though
some compilers support it in C++17.


#include <type_traits>
#include <CGAL/FPU.h>

#ifdef __INTEL_COMPILER
# ifdef __cpp_lib_is_swappable
# undef __cpp_lib_is_swappable
# endif

# ifdef _MSC_VER
# ifdef CGAL_BUG_SQRT
# undef CGAL_BUG_SQRT
# define CGAL_BUG_SQRT( d ) std::sqrt ( d )
# endif
# endif
#endif

On Tue, Dec 8, 2020 at 3:07 PM Aaron Smith <> wrote:
>
> Hi cgal-discuss,
>
> I am new to this list so first of all thanks for the library. I have been 
> using CGAL to build Voronoi tessellations in one of my academic research 
> codes. This works well with gcc and clang compilers, but when I try to use 
> intel compilers on some supercomputers I get errors like the ones shown 
> below (for example). I have success with Intel on 1 supercomputer but get 
> these errors on 3 others. Is this a known issue? Am I missing something or 
> is Intel not expected to be supported?
>
> Note: CGAL version 5.1.1 and Intel 19 on linux (but no root access) 
> systems. Installing headers locally and including via Makefile (not from 
> CMake). I am using -std=c++17
>
> Thanks,
> Aaron
>
> —
>
> local/include/CGAL/Kernel/hash_functions.h(25): error: namespace "std" has 
> no member "enable_if_t"
>   inline std::enable_if_t<std::is_same<typename K::Rep_tag, 
> Cartesian_tag>::value, std::size_t>
>               ^
>
> In file included from local/include/CGAL/Kernel/global_functions.h(25),
>                  from local/include/CGAL/Cartesian/Cartesian_base.h(22),
>                  from local/include/CGAL/Simple_cartesian.h(20),
>                  from 
> local/include/CGAL/Exact_predicates_inexact_constructions_kernel.h(20),
>                  from src/geometry/cgal.h(16),
>                  from src/geometry/cgal.cc(13):
> local/include/CGAL/Kernel/hash_functions.h(25): error: expected a ";"
>   inline std::enable_if_t<std::is_same<typename K::Rep_tag, 
> Cartesian_tag>::value, std::size_t>
>                          ^
>
> In file included from local/include/CGAL/Kernel/global_functions.h(25),
>                  from local/include/CGAL/Cartesian/Cartesian_base.h(22),
>                  from local/include/CGAL/Simple_cartesian.h(20),
>                  from 
> local/include/CGAL/Exact_predicates_inexact_constructions_kernel.h(20),
>                  from src/geometry/cgal.h(16),
>                  from src/geometry/cgal.cc(13):
> local/include/CGAL/Kernel/hash_functions.h(195): error: no instance of 
> overloaded function "CGAL::hash_value" matches the argument list
>             argument types are: (const CGAL::Bbox_2)
>       return CGAL::hash_value (bbox);
>              ^
> local/include/CGAL/Kernel/hash_functions.h(22): note: this candidate was 
> rejected because at least one template argument could not be deduced
>   using boost::hash_value;
>                ^
>
> --
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