Detection and versioning of operating systems, compilers, architecture and other element are traditionally done using preprocessor macros. Library like Boost.Predef provides a sanitized interface on top of those but still live in a world where the preprocessor is king.

SPY is a C++20 (and onward) library that gathers similar information and provides a constexpr compatible interface to access those information, thus making their exploitation within constexpr context possible.

Some References

A Short Example

#include <iostream>
#include <spy/spy.hpp>
 
int main()
{
  std::cout << "OS                : " << spy::operating_system      << std::endl;
  std::cout << "CPU Architecture  : " << spy::architecture          << std::endl;
  std::cout << "SIMD Instructions : " << spy::simd_instruction_set  << std::endl;
  std::cout << "Compiler          : " << spy::compiler              << std::endl;
  std::cout << "libc version      : " << spy::libc                  << std::endl;
  std::cout << "libstd            : " << spy::stdlib                << std::endl;
}

Licence

This library is licensed under the Boost Software License:

Copyright : SPY Project Contributors
 
Permission is hereby granted, free of charge, to any person or organization obtaining a copy of the
software and accompanying documentation covered by this license (the "Software") to use, reproduce,
display, distribute, execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to do so, all subject to the
following:
 
The copyright notices in the Software and this entire statement, including the above license grant,
this restriction and the following disclaimer, must be included in all copies of the Software, in
whole or in part, and all derivative works of the Software, unless such copies or derivative works
are solely in the form of machine-executable object code generated by a source language processor.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND
NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE
BE LIABLE FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

	spy v1.1.0 Julienne Aisner