evalengine: Implement TO_DAYS

[beingnoble03]

Description

This PR adds implementation of TO_DAYS func in evalengine.

Related Issue(s)

Fixes part of #9647

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
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• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

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[codecov]

Codecov Report

Attention: 18 lines in your changes are missing coverage. Please review.

Comparison is base (fd99639) 47.68% compared to head (ec4e4ac) 47.64%.

❗ Current head ec4e4ac differs from pull request most recent head 0f0ebf6. Consider uploading reports for the commit 0f0ebf6 to get more accurate results

Files	Patch %	Lines
go/vt/vtgate/evalengine/cached_size.go	0.00%	10 Missing ⚠️
go/vt/vtgate/evalengine/fn_time.go	89.28%	2 Missing and 1 partial ⚠️
go/vt/vtgate/evalengine/translate_builtin.go	40.00%	2 Missing and 1 partial ⚠️
go/mysql/datetime/datetime.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15065      +/-   ##
==========================================
- Coverage   47.68%   47.64%   -0.05%     
==========================================
  Files        1155     1151       -4     
  Lines      240064   239761     -303     
==========================================
- Hits       114472   114228     -244     
+ Misses     116990   116927      -63     
- Partials     8602     8606       +4     

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[dbussink]

https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_to-days has these cases:

TO_DAYS(950501);
TO_DAYS('2007-10-07');
TO_DAYS('2008-10-07'),
TO_DAYS('08-10-07');
TO_DAYS('0000-00-00');
TO_DAYS('0000-01-01');

Can you add the ones from there missing to make sure they all pass?

[beingnoble03]

done.

[dbussink]

We also have evalToDate, should that be used here instead? The compiler uses Convert_xD which convers to Date as well (vs Convert_xDT which is to DateTime). We should be consistent between the compiler and evaluator.

[beingnoble03]

true, used evalToDate instead of evalToDateTime

[vmg]

Looks great. Could you please remove the redundant nil check?

[dbussink]

@beingnoble03 Can you resolve the conflict here now that #15058 was merged? Fwiw, it's also fine for any (future) PR to implement more than 1 function. I've often implemented classes of related functions in one go before as well to reduce having many PRs in flight in parallel and having to deal with conflicts.

[beingnoble03]

@dbussink done.

Sure. I'll try to implement multiples functions in future PRs.