Reducers not available when using c++17?

[alejandroarmas]

Describe the bug

Hi I was wondering if Reducers are depreciated because when I compiled with c++17, I got an error.

Expected behavior

Compiled Program when using the -std=c++17 flag.

OpenCilk version

Built from source.

clang version 12.0.0 (git@github.com:OpenCilk/opencilk-project.git 5d2851d)
Target: arm64-apple-darwin21.4.0
Thread model: posix
InstalledDir: /Users/alejandro/Downloads/opencilk-project/llvm/build/bin

However, my source does not compile if I include the header:

#include <cilk/reducer.h>

This leads to the following message.

(base) alejandro@Voyager NeuralNetworkPlusPlus % make
clang++ -Werror -I include -fopencilk -std=c++17 -pthread -Wall -O3 -gdwarf-3  -c m_algorithms.cpp -o m_algorithms.o
In file included from m_algorithms.cpp:4:
In file included from /Users/alejandro/Downloads/opencilk-project/llvm/build/lib/clang/12.0.0/include/cilk/reducer.h:64:
/Users/alejandro/Downloads/opencilk-project/llvm/build/lib/clang/12.0.0/include/cilk/metaprogramming.h:225:18: error: no template named 'pointer_to_binary_function' in namespace 'std'
    typedef std::pointer_to_binary_function<A, B, R> type;
            ~~~~~^

I noticed that std::pointer_to_binary_function is depreciated in c++17, how should I proceed? Thanks!

[neboat]

Thanks for reporting the bug.

Can you try the following change and let me know if it works for you?

• Replace lines 225 and 233 in opencilk-project/cheetah/include/cilk/metaprogramming.h with the following:

typedef std::function<R(A,B)> type;

• Inside your build directory, run cmake --build . (to update your build to reflect the change above).

Assuming that works, I'll queue up this change for the next OpenCilk release.

[neboat]

We have completely changed the implementation for reducers in the latest release. The relevant header file is no longer part of OpenCilk.

The new implementation of reducers should work with C++17. There is some minimal documentation about using the new reducer syntax and implementation in the release notes. We are preparing more complete user documentation on reducers, which we plan to post on the OpenCilk website, www.opencilk.org.