Fix nullptr dereference in vector_base::fill_insert

[charan-003]

[BUG FIX] Fix nullptr dereference in vector_base::fill_insert for empty vectors

Summary

This PR fixes a nullptr dereference that occurs when calling fill_insert on an empty thrust::vector or thrust::device_vector. The issue was that the function would attempt to access begin(), end(), or position on unallocated storage.

Changes

1. Added a special case for empty vectors that:
   • Handles allocation if needed
   • Uses uninitialized_fill_n directly to avoid iterator operations on unallocated storage

Fixes #2964

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[charan-003]

Hi @miscco ,

Thank you for your guidance on this issue! I assume that the suggested approach of filling the entire vector with x would change the intended behavior of fill_insert from "inserting at position" to "resizing and filling.

[bernhardmgruber]

/ok to test 08d1ded

[github-actions[bot]]

🥳 CI Workflow Results

🟩 Finished in 4h 21m: Pass: 100%/159 | Total: 6d 22h | Max: 4h 20m | Hits: 69%/190941

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[charan-003]

@bernhardmgruber @miscco Just wondering if there are any changes needed or anything else I should do for this PR?

[bernhardmgruber]

I will let @miscco review this PR next week.

[charan-003]

Hi @miscco Please let me know if any changes are needed for this PR.

[miscco]

/ok to test cb9806f

[github-actions[bot]]

😬 CI Workflow Results

🟥 Finished in 2h 32m: Pass: 98%/70 | Total: 2d 15h | Max: 2h 31m | Hits: 68%/115298

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[bernhardmgruber]

/ok to test c596538

[github-actions[bot]]

😬 CI Workflow Results

🟥 Finished in 2h 10m: Pass: 98%/70 | Total: 2d 11h | Max: 2h 09m | Hits: 69%/113023

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[charan-003]

@bernhardmgruber, I hope the failed cases are unrelated to the changes I made

[bernhardmgruber]

@bernhardmgruber, I hope the failed cases are unrelated to the changes I made

Looks like a network issue. I restarted the job.

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😬 CI Workflow Results

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😬 CI Workflow Results

🟥 Finished in 7d 03h: Pass: 1%/70 | Total: 2d 12h | Max: 2h 09m | Hits: 53%/2423

See results here.

[github-actions[bot]]

😬 CI Workflow Results

🟥 Finished in 7d 03h: Pass: 1%/70 | Total: 2d 12h | Max: 2h 09m | Hits: 53%/2423

See results here.