opm-simulators/cmake/Modules/FindQuadmath.cmake

# Module that checks whether the compiler supports the
# quadruple precision floating point math
#
# Sets the following variables:
# HAVE_QUAD
# QUADMATH_LIBRARIES
#
# perform tests
include(CheckCSourceCompiles)
include(CheckCXXSourceCompiles)
include(CMakePushCheckState)

cmake_push_check_state()
list(APPEND CMAKE_REQUIRED_LIBRARIES "quadmath")
CHECK_C_SOURCE_COMPILES("
#include <quadmath.h>

int main(void){
    __float128 foo = sqrtq(123.456);
}" HAVE_QUAD)
cmake_pop_check_state()

if (HAVE_QUAD)
  set(QUADMATH_LIBRARIES "quadmath")
endif()

include(FindPackageHandleStandardArgs)
find_package_handle_standard_args(QuadMath
  DEFAULT_MSG
  QUADMATH_LIBRARIES
  HAVE_QUAD
  )