RAII issue

[tpadioleau]

I suspect potential memory leaks.

Consider the snippet

kokkos-fft/fft/src/KokkosFFT_Cuda_plans.hpp

Lines 39 to 54 in 4582878

	cufftResult cufft_rt = cufftCreate(&(*plan));
	KOKKOSFFT_THROW_IF(cufft_rt != CUFFT_SUCCESS, "cufftCreate failed");
	cudaStream_t stream = exec_space.cuda_stream();
	cufftSetStream((*plan), stream);
	auto type = KokkosFFT::Impl::transform_type<ExecutionSpace, in_value_type,
	out_value_type>::type();
	auto [in_extents, out_extents, fft_extents, howmany] =
	KokkosFFT::Impl::get_extents(in, out, axes, s, is_inplace);
	const int nx = fft_extents.at(0);
	int fft_size = std::accumulate(fft_extents.begin(), fft_extents.end(), 1,
	std::multiplies<>());
	cufft_rt = cufftPlan1d(&(*plan), nx, type, howmany);
	KOKKOSFFT_THROW_IF(cufft_rt != CUFFT_SUCCESS, "cufftPlan1d failed");

It is called inside the Plan constructor. Let's assume the second KOKKOSFFT_THROW_IF actually throws, the backend destroy_plan_and_info function will never be called because the Plan object will never finish construction.

I think we need to adhere to the RAII so that if any exception is thrown the backend plan object gets automatically freed.