#pragma once 

#if defined(__clang__)

  #if __clang_major__ < 3
    #error "This clang++ version is known to not work with Grid due to compiler bugs"
  #endif

  #if __clang_major__ == 3
    #if __clang_minor__ < 5
    #error "This clang++ version is known to not work with Grid due to compiler bugs"
    #endif
  #endif 

// Intel compiler *ALSO* has __GNUC__ defined so must if/else GCC checks
#elif defined(__INTEL_COMPILER)

  #if __INTEL_COMPILER < 1603
    #error "This icpc version is known to not work with Grid due to compiler bugs"
  #endif

#else 

// This macro is annoying many other compilers just define __GNUC__ and claim GCC compat
// but this defeats the use of __GNUC__ to really detect G++
  #if defined(__GNUC__)

    #if __GNUC__ < 4 
      #error "g++ prior to version 4 is known to not work with Grid due to compiler bugs"
    #endif

    #if __GNUC__ == 4 
      #if __GNUC_MINOR__ != 9 
      #error "g++ 4.9 is the only gcc-4.x version known to work with Grid due to compiler bugs"
      #endif
    #endif

    #if __GNUC__ == 5
      #warning "g++ version 5 is known to not work with Grid due to compiler bugs under -O3 : ensure you run make check"
    #endif

    #if __GNUC__ == 6
      #if __GNUC_MINOR__ < 3
        #warning "This g++6.3 is the first recent g++ version known to work with Grid: ensure you run make check"
      #endif
    #endif

  #else

    #warning "Unknown compiler detected: cannot guarantee compatability since Grid tends to break compilers"
    #warning "Ensure to run :  make check"

  #endif

#endif