C++17 constexpr if

Hi @ all,

I am using constexpr if widely within my code. After a successfull build with the gcc I wanted to use *the good stuff*, namely icpc.

Here is a short example of my code:

/*...*/
  virtual inline void run( ) override {
    #pragma omp parallel for
      for( std::size_t i = 0; i < REP_COUNT; ++i ) {
        //...
        if constexpr( ( PROCESS_DATA_COUNT / 4 ) >= 2 ) {
          //...
        }
        if constexpr( ( PROCESS_DATA_COUNT / 4 ) == 4 ) {
          //...
        }
      }
  }

/*...*/

When I try to compile it with the icpc (Version 18.0.0.128 Build 20170811), it breaks with the following output:

/usr/include/c++/7/bits/stl_pair.h(79): error: inline specifier allowed on function declarations only
    _GLIBCXX17_INLINE constexpr piecewise_construct_t piecewise_construct =
    ^

/usr/include/c++/7/utility(345): error: inline specifier allowed on function declarations only
    inline constexpr in_place_t in_place{};
    ^

 ... error: expected a "("
            if constexpr( ( PROCESS_DATA_COUNT / 4 ) >= 2 ) {
               ^

Is there no constexpr if within the newest icpc? Is there a proper workaround?

Sincerely yours