expression: clarify the cast(... as char array) error message | tidb-test=pr/2326

[YangKeao]

What problem does this PR solve?

Issue Number: close #53219

Problem Summary:

The error message was misleading. TiDB actually supports casting to char(16) array. The user needs to add length after facing this error.

What changed and how does it work?

Change the error message to tell the user that the problem is the missed length.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.7175%. Comparing base (601e21c) to head (f829768).
Report is 7 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #53220        +/-   ##
================================================
+ Coverage   72.4105%   74.7175%   +2.3070%     
================================================
  Files          1492       1493         +1     
  Lines        429312     431928      +2616     
================================================
+ Hits         310867     322726     +11859     
+ Misses        99145      89327      -9818     
- Partials      19300      19875       +575     

Flag	Coverage Δ
integration	49.2674% <100.0000%> (?)
unit	71.2853% <0.0000%> (-0.0137%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	50.2308% <ø> (+8.8006%)	⬆️

[YangKeao]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dveeden, zanmato1984

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Needs approval from an approver in each of these files:

• OWNERS [dveeden,zanmato1984]
• pkg/expression/OWNERS [zanmato1984]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-05-13 11:07:56.526336812 +0000 UTC m=+1478630.283472385: ☑️ agreed by dveeden.
• 2024-05-13 11:45:40.052324996 +0000 UTC m=+1480893.809460561: ☑️ agreed by zanmato1984.

[dveeden]

/retest