Compilation error with (amp) restriction specifier in C++ AMP

Question

Hi,
[double post from :
original post ]
I'm using C++ AMP (I'm not that experienced with C++ and I'm new to AMP, so I have to stumble through this stuff) But I thought I had this code working, but now I'm getting the following error:
Error    1    error C3930: 'WRC_Raytracer::RaytracerRTC::RenderSceneWithAMP::<lambda_c13eb21eb34534d03d408733745bcf16>::operator ()' : no overloaded function has restriction specifiers that are compatible with the ambient
context 'Concurrency::_Parallel_for_impl'
Here is my parallel loop (cut down slightly to focus on the issue):
[code]
    parallel_for(0, 720 * 576, 1, [w, cBuffer, pixelDataView](int i) restrict(amp)
                // compute x and y for the given index
                float x = (float)(i % w);
                float y = (float)(i / w);
                // convert color from {0,1}f to {0,255}b
                int bInt, gInt, rInt;
                bInt = (int) (min(x/719.f, 1) * 255);
                gInt = (int) (min(y/575.f, 1) * 255);
                rInt = (int) (min(0, 1) * 255);
                // represent color data as (int)argb
                int pixelAsInt = (255 << 24) + (rInt << 16) + (gInt << 8) + bInt;
                // update pixelData element
                pixelDataView[i] = pixelAsInt;
[/code]              
Can anyone see what's wrong here ? As I said, I'm sure this was working yesterday, and I did something just before shutting down, and now it's not working.
Edit : I tried the parallel_for_each loop that I had started with. And that actually does work ...
parallel_for_each(pixelDataView.extent,[=](index<1> idx) restrict(amp)

Answer 1

Hello Gavin, thank you for your question.
Note that parallel_for_each (more precisely, the overloads that accept extent arguments and take a restrict(amp) functional parameter) is the unique entry-point for C++ AMP execution. Other functions in the concurrency namespace, such as parallel_for,
are unrelated, and stem from a different technology (PPL). Since restrict(amp) is specific to C++ AMP, trying to use a restrict(amp) functional object in any context but that of C++ AMP execution, is not possible - hence the compiler error
you were seeing. Hopefully this turns out helpful for you. Also, congratulations for picking up C++ AMP, I hope you like it! Cheers!