Add transform_output_iterator and transform_input_output_iterator default constructors

[harrism]

Fixes #1804

This PR adds default constructors to transform_output_iterator and transform_input_output_iterator. It also adds a unit test of transform_output_iterator with reduce_by_key which fails to compile before this change. With this change it compiles and runs correctly.

All other Thrust fancy iterators have default constructors, so I think this change improves consistency.

Sorry about all the formatting changes -- Thrust includes a .clang-format, but apparently doesn't use it to format files, so when I saved these files, clang-format reformatted them (I have format-on-save enabled). If this is a problem, I can resubmit without clang-formatting. To review just the functional changes, look for TestTransformOutputIteratorReduceByKey, and in the headers look for = default

[miscco]

Thanks for tracking the bug down!

I have some minor comment about defaulting instead of defining but besides that it looks good

[miscco]

run tests

[davidwendt]

I would recommend undoing the formatting if only to make it easier to create a patch for this change.

[miscco]

I would recommend undoing the formatting if only to make it easier to create a patch for this change.

I believe that is fine, one can ignore whitespace changes in the github UI so the number of changes to review is rather small

[miscco]

Something is strange here

09:59:32 CMake Error at /workspace/cmake/ThrustRunTest.cmake:7 (message):
09:59:32   /workspace/build/bin/thrust.cpp.tbb.cpp11.test.transform_output_iterator
09:59:32   failed (No such file or directory)

[miscco]

Yeah it seesm that tbb is cranky:

testing/CMakeFiles/thrust.cpp.tbb.cpp11.test.transform_output_iterator.dir/thrust.cpp.tbb.cpp11/transform_output_iterator.cu.cpp.o -c /workspace/build/testing/thrust.cpp.tbb.cpp11/transform_output_iterator.cu.cpp
09:09:07 /workspace/thrust/cmake/../../thrust/system/tbb/detail/reduce_by_key.inl(329): error: function "thrust::plus<T>::operator() [with T=signed char]" cannot be called with the given argument list
09:09:07             argument types are: (thrust::detail::transform_output_iterator_proxy<thrust::negate<signed char>, thrust::detail::normal_iterator<thrust::device_ptr<signed char>>>, thrust::reference<signed char, thrust::pointer<signed char, thrust::system::tbb::detail::par_t, thrust::use_default, thrust::use_default>, thrust::use_default>)
09:09:07             object type is: thrust::plus<signed char>
09:09:07         values_result[output_idx] = binary_op(values_result[output_idx], carries[i]);
09:09:07                                     ^
09:09:07 /workspace/thrust/cmake/../../thrust/functional.h(231): note: this candidate was rejected because arguments do not match
09:09:07     constexpr T operator()(const T &lhs, const T &rhs) const
09:09:07                 ^
09:09:07           detected during:
09:09:07             instantiation of "thrust::pair<OutputIterator1, OutputIterator2> thrust::system::tbb::detail::reduce_by_key(thrust::system::tbb::detail::execution_policy<DerivedPolicy> &, InputIterator1, InputIterator1, InputIterator2, OutputIterator1, OutputIterator2, BinaryPredicate, BinaryFunction) [with DerivedPolicy=thrust::system::tbb::detail::par_t, InputIterator1=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>,
09:09:07                       InputIterator2=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>, OutputIterator1=thrust::discard_iterator<signed char>, OutputIterator2=thrust::transform_output_iterator<thrust::negate<signed char>, thrust::detail::normal_iterator<thrust::device_ptr<signed char>>>, BinaryPredicate=thrust::equal_to<signed char>, BinaryFunction=thrust::plus<signed char>]" at line 135 of "/workspace/thrust/cmake/../../thrust/detail/reduce.inl"
09:09:07             instantiation of "thrust::pair<OutputIterator1, OutputIterator2> thrust::reduce_by_key(const thrust::detail::execution_policy_base<DerivedPolicy> &, InputIterator1, InputIterator1, InputIterator2, OutputIterator1, OutputIterator2, BinaryPredicate, BinaryFunction) [with DerivedPolicy=thrust::system::tbb::detail::par_t, InputIterator1=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>, InputIterator2=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>,
09:09:07                       OutputIterator1=thrust::discard_iterator<signed char>, OutputIterator2=thrust::transform_output_iterator<thrust::negate<signed char>, thrust::detail::normal_iterator<thrust::device_ptr<signed char>>>, BinaryPredicate=thrust::equal_to<signed char>, BinaryFunction=thrust::plus<signed char>]" at line 185 of "/workspace/thrust/cmake/../../thrust/system/detail/generic/reduce_by_key.inl"
09:09:07             instantiation of "thrust::pair<OutputIterator1, OutputIterator2> thrust::system::detail::generic::reduce_by_key(thrust::execution_policy<DerivedPolicy> &, InputIterator1, InputIterator1, InputIterator2, OutputIterator1, OutputIterator2, BinaryPredicate) [with DerivedPolicy=thrust::system::tbb::detail::par_t, InputIterator1=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>, InputIterator2=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>,
09:09:07                       OutputIterator1=thrust::discard_iterator<signed char>, OutputIterator2=thrust::transform_output_iterator<thrust::negate<signed char>, thrust::detail::normal_iterator<thrust::device_ptr<signed char>>>, BinaryPredicate=thrust::equal_to<signed char>]" at line 111 of "/workspace/thrust/cmake/../../thrust/detail/reduce.inl"
09:09:07             instantiation of "thrust::pair<OutputIterator1, OutputIterator2> thrust::reduce_by_key(const thrust::detail::execution_policy_base<DerivedPolicy> &, InputIterator1, InputIterator1, InputIterator2, OutputIterator1, OutputIterator2, BinaryPredicate) [with DerivedPolicy=thrust::system::tbb::detail::par_t, InputIterator1=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>, InputIterator2=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>,
09:09:07                       OutputIterator1=thrust::discard_iterator<signed char>, OutputIterator2=thrust::transform_output_iterator<thrust::negate<signed char>, thrust::detail::normal_iterator<thrust::device_ptr<signed char>>>, BinaryPredicate=thrust::equal_to<signed char>]" at line 152 of "/workspace/thrust/cmake/../../thrust/system/detail/generic/reduce_by_key.inl"
09:09:07             instantiation of "thrust::pair<OutputIterator1, OutputIterator2> thrust::system::detail::generic::reduce_by_key(thrust::execution_policy<DerivedPolicy> &, InputIterator1, InputIterator1, InputIterator2, OutputIterator1, OutputIterator2) [with DerivedPolicy=thrust::system::tbb::detail::par_t, InputIterator1=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>, InputIterator2=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>,
09:09:07                       OutputIterator1=thrust::discard_iterator<signed char>, OutputIterator2=thrust::transform_output_iterator<thrust::negate<signed char>, thrust::detail::normal_iterator<thrust::device_ptr<signed char>>>]" at line 89 of "/workspace/thrust/cmake/../../thrust/detail/reduce.inl"
09:09:07             instantiation of "thrust::pair<OutputIterator1, OutputIterator2> thrust::reduce_by_key(const thrust::detail::execution_policy_base<DerivedPolicy> &, InputIterator1, InputIterator1, InputIterator2, OutputIterator1, OutputIterator2) [with DerivedPolicy=thrust::system::tbb::detail::par_t, InputIterator1=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>, InputIterator2=thrust::detail::normal_iterator<thrust::device_ptr<signed char>>,
09:09:07                       OutputIterator1=thrust::discard_iterator<signed char>, OutputIterator2=thrust::transform_output_iterator<thrust::negate<signed char>, thrust::detail::normal_iterator<thrust::device_ptr<signed char>>>]" at line 127 of "/workspace/testing/transform_output_iterator.cu"
09:09:07             instantiation of "void TestTransformOutputIteratorReduceByKey<T>::operator()(size_t={unsigned long}) [with T=signed char]" at line 56 of "/workspace/testing/unittest/meta.h"
09:09:07             instantiation of "void unittest::for_each_type<TypeList, Function, T, i>::operator()(U) [with TypeList=SignedIntegralTypes, Function=TestTransformOutputIteratorReduceByKey, T=signed char, i=0U, U=size_t={unsigned long}]" at line 567 of "/workspace/testing/unittest/testframework.h"
09:09:07             instantiation of "void VariableUnitTest<TestName, TypeList>::run() [with TestName=TestTransformOutputIteratorReduceByKey, TypeList=SignedIntegralTypes]" 
09:09:07 

09:09:07 /workspace/thrust/cmake/../../thrust/system/tbb/detail/reduce_by_key.inl(329): error: function "thrust::plus<T>::operator() [with T=short]" cannot be called with the given argument list
09:09:07             argument types are: (thrust::detail::transform_output_iterator_proxy<thrust::negate<signed short>, thrust::detail::normal_iterator<thrust::device_ptr<short>>>, thrust::reference<short, thrust::pointer<short, thrust::system::tbb::detail::par_t, thrust::use_default, thrust::use_default>, thrust::use_default>)
09:09:07             object type is: thrust::plus<short>
09:09:07         values_result[output_idx] = binary_op(values_result[output_idx], carries[i]);

[harrism]

I have no idea how to investigate TBB failures. Where do I start? How do I build with TBB locally?

[harrism]

I removed the clang-format formatting changes so now the changes are only the functional ones. I still don't know how to solve the TBB failures -- I think my new test may have exposed an existing problem with the TBB backend...

[harrism]

OK I split the new test into its own source file and disabled it on TBB for now. I filed NVIDIA/cccl#821 to report the TBB backend bug.

[griwes]

run tests

[harrism]

Cool, we're passing now.

[miscco]

@wmaxey AFAIK we already have the 2.0.X branch, so I believe we should be able to merge this to main?

[miscco]

@senior-zero can we merge this?

[gevtushenko]

It seems that I've fixed the initial issue with reduce by key here. In any way, having a defaulted default constructor wouldn't hurt. As I understand, the defaulted default constructors will be deleted if subobjects (output iterator and invocable) are not default constructible.