MDEV-31334: Consider dates ending in 'T' as malformed

[FarihaIS]

Description

MariaDB 10.6 currently accepts dates that end in 'T' without a warning or error: for example 'insert into t1 values ("2003-02-05T")'. This is an issue as ISO 8601 standards state that a 'T' should be followed by the time of day. Dates that terminate in 'T' should receive the same error in strict mode and warning otherwise as dates that terminate in any other (invalid) character. Commit includes bug fix and tests for dates ending in 'T'.

How can this PR be tested?

Execute the main suite in mysql-test-run. This commit adds a test in that suite.

Basing the PR against the correct MariaDB version

• This is a new feature and the PR is based against the latest MariaDB development branch

Backward compatibility

This is a new feature introducing stricter date formatting that will consider dates ending in 'T' as malformed and affect backwards compatibility.

Copyright

All new code of the whole pull request, including one or several files that are either new files or modified ones, are contributed under the BSD-new license. I am contributing on behalf of my employer Amazon Web Services, Inc.

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[cvicentiu]

@FarihaIS Thank you for the contribution! 👍

I've done a preliminary review and I think you should first try to clarify in the MDEV what the exact specification is.

How should SELECT EXTRACT(<malformed_date>) should work. How it should work for INSERT. How it should behave with STRICT mode vs not strict mode.

Then you should check your patch again and see if it fulfils (and tests) those scenarios.

I'm sure we can get this through with a bit more work. :)