C++20 #include <concepts>, oneAPI 2025.1 Linux

[drcolossus]

In oneAPI 2025.1, the attached test program fails to compile as-is ("icpx -c concept.cpp")

It complains about the include file not being found.

I can get the code to compile by including the absolute path to concepts.hpp, but I shouldn't have to. Also, the above code works fine in oneAPI 2024.1. Is there a trick to using C++20 concepts in 2025.1?

#include <concepts>

double add(double x, double y) {
return x + y;
}

[Viet_H_Intel]

I don't think we have released oneAPI2025.1.

The test case compiled with oneAPI2025.0.1. 

$ icpx concept.cpp -c -V
Intel(R) oneAPI DPC++/C++ Compiler for applications running on Intel(R) 64, Version 2025.0.4 Build 20241205
Copyright (C) 1985-2024 Intel Corporation. All rights reserved.

$ cat concept.cpp
#include <concepts>

double add(double x, double y) {
return x + y;
}

Which gcc version you have on your host?

[drcolossus]

Thanks for your reply. Our IT people installed it under the name "oneAPI 2025.1" but it appears to actually be 2025.0.1:

$ icpx concepts.cpp -c -V
Intel(R) oneAPI DPC++/C++ Compiler for applications running on Intel(R) 64, Version 2025.0.4 Build 20241205
Copyright (C) 1985-2024 Intel Corporation. All rights reserved.

As for gcc, I'm using the base RHEL 8.1 compilers:

$ gcc --version
gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-22)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[drcolossus]

One curious observation is that while our 2024.1 folder has these two files named "concepts*":

$MKL_ROOT/include/oneapi/mkl/lapack/concepts.hpp
$DPL_ROOT/include/pstl_offload/concepts

Our 2025.0 folder only has this one:

$MKL_ROOT/include/oneapi/mkl/lapack/concepts.hpp

As far as I can tell, the IT dept selected all of the available options when installing. Could the installer have silently skipped installing the SYCL offload packages for some reason?

[Viet_H_Intel]

icpx will be compatible with Gnu version on your host. 

Will you get the same error if you do "g++ concept.cpp -c"?

[drcolossus]

It doesn't work on g++ either:

$ g++ --version
g++ (GCC) 8.5.0 20210514 (Red Hat 8.5.0-22)
Copyright (C) 2018 Free Software Foundation, Inc.

$ g++ -c concepts.cpp
concepts.cpp:1:10: fatal error: concepts: No such file or directory
#include <concepts>
^~~~~~~~~~
compilation terminated.

[drcolossus]

Aha! If I enable RHEL8's gcc-toolset-10 or later it works! It does not work with gcc-toolset-9 or the stock gcc 8.5. The oneAPI 2025.0 system requirements say that GCC 7.5 ought to be good enough, but that does not seem to be the case.

gcc-toolset-10 provides the concepts file, but gcc-toolset-9 does not:

$ rpm -ql gcc-toolset-9-libstdc++-devel | grep concepts

$ rpm -ql gcc-toolset-10-libstdc++-devel | grep concepts
/opt/rh/gcc-toolset-10/root/usr/include/c++/10/bits/iterator_concepts.h
/opt/rh/gcc-toolset-10/root/usr/include/c++/10/concepts

[drcolossus · Accepted solution]

In fact there's a note on this specific symptom here.

So I guess the guidance for my user is to use gcc-toolset-10 or later when using 2025.0. For 2024 or earlier it appears that you can use RHEL8's default GCC 8.5.

[Viet_H_Intel]

For 2024 or earlier it appears that you can use RHEL8's default GCC 8.5.

I doubt that oneAPI2024.* won't error out with gcc8.5