An empty NDArray should have size 0

[ziyuang]

Description

(Brief description on what this PR is about)

Checklist

Essentials

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [MXNET-$JIRA_ID], where $JIRA_ID refers to the relevant JIRA issue created (except PRs with tiny changes)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage:
• Unit tests are added for small changes to verify correctness (e.g. adding a new operator)
• Nightly tests are added for complicated/long-running ones (e.g. changing distributed kvstore)
• Build tests will be added for build configuration changes (e.g. adding a new build option with NCCL)
• Code is well-documented:
• For user-facing API changes, API doc string has been updated.
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• To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

Changes

• Feature1, tests, (and when applicable, API doc)
• Feature2, tests, (and when applicable, API doc)

Comments

• If this change is a backward incompatible change, why must this change be made.
• Interesting edge cases to note here

[Roshrini]

@ziyuang Can you add unittest for this change?

[reminisce]

Can you confirm that an empty shape represents an empty ndarray in cpp-package? In Python and C++ backend, an empty shape actually represents a scalar tensor.

[ziyuang]

Can you confirm that an empty shape represents an empty ndarray in cpp-package? In Python and C++ backend, an empty shape actually represents a scalar tensor.

The expected behavior is to return 0 when the array is empty; now I do this check directly without touching the shape vector.

[ziyuang]

@ziyuang Can you add unittest for this change?

Will add a standalone one under tests/cpp/misc/ if that's good for you

[vandanavk]

@ziyuang please fill in the PR description template with relevant details about the changes

[pinaraws]

@mxnet-label-bot add[pr-awaiting-response]

[pinaraws]

@mxnet-label-bot remove[pr-awaiting-review]

[abhinavs95]

@ziyuang any update on the PR? Also please fill the PR description with relevant details.

[piyushghai]

@apeforest For review.

[Roshrini]

@ziyuang any update on the PR?

[ziyuang]

Hi, has this zero-size NDArray issue been handled well by #14661 already?

[karan6181]

@ziyuang Could you please see if #14661 fix your issue or not by running small reproducible code and installing the latest pre-release version of MXNet.

[piyushghai]

@ziyuang Ping for an update.

[roywei]

@ziyuang please trigger CI and update this PR?