On the oneAPI backend, indexing a 1-D array that is a slice with a non-zero offset (e.g. data(af::seq(10, 29))) by an index array returns elements counted from the start of the underlying array instead of from the slice.

Description

• Official Windows installer, ArrayFire v3.10.0 (build 492718b).
• Backend: oneAPI only. The same binary on the same GPU gives correct results with the OpenCL backend and the CPU backend; CUDA / OpenCL / CPU on an NVIDIA machine are also correct.
• af::lookup(slice, idx), indexing the slice with a seq, and indexing a copy() of the slice are all correct; only slice(idx_array) (and af::flat(slice)(idx_array)) are wrong.
• Reproducible every run.
• Workaround: use af::lookup(slice, idx) or slice.copy()(idx).
• Expected: view(idx) equals af::lookup(view, idx), as on the other backends.

Found while training word2vec on the device: each mini-batch is a slice of the epoch's examples, and picking rows from it this way updated the wrong rows on oneAPI (the loss rose instead of falling).

Related: #3732 (another oneAPI indexing issue, indexed min / max along dim 1).

Reproducible Code and/or Steps

#include <arrayfire.h>

int main() {
    af::setBackend(AF_BACKEND_ONEAPI);
    af::info();
    const af::array data = af::range(af::dim4(100), 0, f32);  // 0 .. 99
    const af::array view = data(af::seq(10, 29));             // 10 .. 29
    const unsigned i[4] = {0, 1, 2, 3};
    const af::array idx(4, i);
    af_print(view(idx));              // oneAPI: 0 1 2 3   expected: 10 11 12 13
    af_print(af::lookup(view, idx));  // 10 11 12 13 on every backend
    return 0;
}

Output of a fuller probe on oneAPI device 0 (the same binary prints all checks ok with opencl and cpu on that machine):

ArrayFire v3.10.0 (oneAPI, 64-bit Windows, build 492718b5a)
[0] Intel(R) OpenCL Graphics: Intel(R) Iris(R) Xe Graphics, 7129 MB (fp16 )
expected: 10 11 12 13
view(idx)                      WRONG got 0 1 2 3
flat(view)(idx)                WRONG got 0 1 2 3
lookup(view, idx)              ok    got 10 11 12 13
view(seq(0, 3))                ok    got 10 11 12 13
some checks WRONG

System Information

1. ArrayFire v3.10.0 (build 492718b), official Windows installer.
2. Intel Core i5-1135G7 with Intel Iris Xe Graphics, driver 32.0.101.7088 (2026-06-17). Windows 11 Pro Education, build 26300.
3. af::info():

ArrayFire v3.10.0 (oneAPI, 64-bit Windows, build 492718b5a)
[0] Intel(R) OpenCL Graphics: Intel(R) Iris(R) Xe Graphics, 7129 MB (fp16 )
-1- Intel(R) OpenCL: 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz, 16126 MB (fp64 fp16 )