build issue: std::reduce about gray16lib HOT 3 CLOSED

The standard does have a two argument version and this works in Xcode 10.2. Might be an issue with the Intel Parallel STL implementation; I haven't started peeling the onion back.

As a workaround, std::accumulate will also work.

   // Draw Cumulative Value
-  int sum = std::reduce(histogram.constBegin(), histogram.constEnd());
+  int sum = std::accumulate(histogram.constBegin(), histogram.constEnd(), 0);
   const auto sumScale = static_cast<double> (height) / static_cast<double> (sum);

from gray16lib.

int sum = std::accumulate(histogram.constBegin(), histogram.constEnd(), 0); does the trick

Thanks

from gray16lib.

Re-opening just to ensure I formally correct this since std::reduce isn't widely supported yet.

The code should use the feature macro __cpp_lib_parallel_algorithm (and possibly compiler defines to identify if it's being compiled by Apple Clang which implements std::reduce but doesn't set feature macros) to use the std::reduce otherwise it should use std::accumulate.

from gray16lib.