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COMP: Silence nodiscard warnings for Future.get() in PoolMultiThreader #5945

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COMP: Silence nodiscard warnings for Future.get() in PoolMultiThreader #5945

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4 changes: 2 additions & 2 deletions Modules/Core/Common/src/itkPoolMultiThreader.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -145,7 +145,7 @@ PoolMultiThreader::SingleMethodExecute()
// so now it waits for each of the other work units to finish
for (threadLoop = 1; threadLoop < m_NumberOfWorkUnits; ++threadLoop)
{
exceptionHandler.TryAndCatch([this, threadLoop] { m_ThreadInfoArray[threadLoop].Future.get(); });
exceptionHandler.TryAndCatch([this, threadLoop] { (void)m_ThreadInfoArray[threadLoop].Future.get(); });
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@N-Dekker N-Dekker Mar 14, 2026 •
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What does Future.get() return? And why is it OK to ignore its return value?

I'm asking, because maybe we should use the std::future<void> specialization, for Future: https://en.cppreference.com/w/cpp/thread/future/get.html
std::future<void>::get() returns void. It looks like that's what we want, right?

In general, I think it's preferable to avoid unnecessary casting 🤷

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@hjmjohnson hjmjohnson Mar 14, 2026

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std::future<ITK_THREAD_RETURN_TYPE> Future;

ITK_THREAD_RETURN_TYPE depends on the platform.

I don't understand what you are suggesting. Could you please make an alternate proposal?

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@N-Dekker N-Dekker Mar 15, 2026

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Ah, I see:

ITK_THREAD_RETURN_TYPE is a pointer type when using Pthreads:

ITK/Modules/Core/Common/include/itkThreadSupport.h

Line 47 in badec43

using ITK_THREAD_RETURN_TYPE = void *;

And it's unsigned int when using WIN32 threads:

ITK/Modules/Core/Common/include/itkThreadSupport.h

Line 62 in badec43

using ITK_THREAD_RETURN_TYPE = unsigned int;

But "normally" it's just void:

ITK/Modules/Core/Common/include/itkThreadSupport.h

Line 77 in badec43

using ITK_THREAD_RETURN_TYPE = void;

Are Pthreads and WIN32 threads both still actively supported nowadays?

}

exceptionHandler.RethrowFirstCaughtException();
Expand Down Expand Up @@ -300,7 +300,7 @@ PoolMultiThreader::ParallelizeImageRegion(unsigned int dimension,
filter->IncrementProgress(0);
}
} while (status != std::future_status::ready);
m_ThreadInfoArray[i].Future.get();
(void)m_ThreadInfoArray[i].Future.get();
reporter.CompletedPixel();
});
}
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