Fix docs bugs and use correct accumulator and intermediate result types

thrust/testing/cuda/transform_scan.cu

@@ -127,7 +127,7 @@ void TestTransformScanDevice(ExecutionPolicy exec)
   }
 
   iter = iter_vec[0];
-  ref  = {2, -1, 1, -3, 2};
+  ref  = {3, 2, -1, 1, -3};
   ASSERT_EQUAL(std::size_t(iter - output.begin()), input.size());
   ASSERT_EQUAL(input, input_copy);
   ASSERT_EQUAL(ref, output);

thrust/thrust/system/cuda/detail/transform_scan.h

@@ -79,11 +79,13 @@ OutputIt _CCCL_HOST_DEVICE transform_inclusive_scan(
   InitialValueType init,
   ScanOp scan_op)
 {
-  using result_type = ::cuda::std::__accumulator_t<ScanOp, cub::detail::value_t<InputIt>, InitialValueType>;
+  using input_type  = typename thrust::iterator_value<InputIt>::type;
+  using result_type = thrust::detail::invoke_result_t<TransformOp, input_type>;
+  using value_type  = thrust::remove_cvref_t<result_type>;
 
   using size_type              = typename iterator_traits<InputIt>::difference_type;
   size_type num_items          = static_cast<size_type>(thrust::distance(first, last));
-  using transformed_iterator_t = transform_input_iterator_t<result_type, InputIt, TransformOp>;
+  using transformed_iterator_t = transform_input_iterator_t<value_type, InputIt, TransformOp>;
 
   return cuda_cub::inclusive_scan_n(
     policy, transformed_iterator_t(first, transform_op), num_items, result, init, scan_op);

thrust/thrust/system/detail/generic/transform_scan.inl

@@ -79,7 +79,9 @@ _CCCL_HOST_DEVICE OutputIterator transform_inclusive_scan(
   InitialValueType init,
   BinaryFunction binary_op)
 {
-  using ValueType = thrust::remove_cvref_t<InitialValueType>; // cuda::std::__accumulator_t?
+  using InputType  = typename thrust::iterator_value<InputIterator>::type;
+  using ResultType = thrust::detail::invoke_result_t<UnaryFunction, InputType>;
+  using ValueType  = thrust::remove_cvref_t<ResultType>;
 
   thrust::transform_iterator<UnaryFunction, InputIterator, ValueType> _first(first, unary_op);
   thrust::transform_iterator<UnaryFunction, InputIterator, ValueType> _last(last, unary_op);

thrust/thrust/transform_scan.h

@@ -174,8 +174,8 @@ OutputIterator transform_inclusive_scan(
  *  performing an \p inclusive_scan on the tranformed sequence.  In most
  *  cases, fusing these two operations together is more efficient, since
  *  fewer memory reads and writes are required. In \p transform_inclusive_scan,
- *  <tt>binary_op(unary_op(\*first), init)</tt> is assigned to
- *  <tt>\*result</tt> and the result of <tt>binary_op(unary_op(\*result),
+ *  if <tt>binary_op(init, unary_op(\*first))</tt> is <tt>accum</tt>, it is assigned to
+ *  <tt>\*result</tt> and the result of <tt>binary_op(accum,
  *  unary_op(\*(first + 1)))</tt> is assigned to <tt>\*(result + 1)</tt>,
  *  and so on. The transform scan operation is permitted to be in-place.
  *
@@ -186,7 +186,7 @@ OutputIterator transform_inclusive_scan(
  *  \param last The end of the input sequence.
  *  \param result The beginning of the output sequence.
  *  \param unary_op The function used to tranform the input sequence.
- *  \param init The initial value of the \p inclusive_scan
+ *  \param init The initial value of the \p transform_inclusive_scan
  *  \param binary_op The associatve operator used to 'sum' transformed values.
  *  \return The end of the output sequence.
  *
@@ -239,6 +239,7 @@ _CCCL_HOST_DEVICE OutputIterator transform_inclusive_scan(
   InputIterator first,
   InputIterator last,
   OutputIterator result,
+  UnaryFunction unary_op,
   T init,
   AssociativeOperator binary_op);
 
@@ -247,17 +248,17 @@ _CCCL_HOST_DEVICE OutputIterator transform_inclusive_scan(
  *  tranformation defined by \p unary_op into a temporary sequence and then
  *  performing an \p inclusive_scan on the tranformed sequence.  In most
  *  cases, fusing these two operations together is more efficient, since
- *  fewer memory reads and writes are required. In \p transform_inclusive_scan,
- *  <tt>binary_op(unary_op(\*first), init)</tt> is assigned to
- *  <tt>\*result</tt> and the result of <tt>binary_op(unary_op(\*result),
+ *  fewer memory reads and writes are required.In \p transform_inclusive_scan,
+ *  if <tt>binary_op(init, unary_op(\*first))</tt> is <tt>accum</tt>, it is assigned to
+ *  <tt>\*result</tt> and the result of <tt>binary_op(accum,
  *  unary_op(\*(first + 1)))</tt> is assigned to <tt>\*(result + 1)</tt>,
  *  and so on. The transform scan operation is permitted to be in-place.
  *
  *  \param first The beginning of the input sequence.
  *  \param last The end of the input sequence.
  *  \param result The beginning of the output sequence.
  *  \param unary_op The function used to tranform the input sequence.
- *  \param init The initial value of the \p inclusive_scan
+ *  \param init The initial value of the \p transform_inclusive_scan
  *  \param binary_op The associatve operator used to 'sum' transformed values.
  *  \return The end of the output sequence.
  *