INTL0202: Flag DateTimeOffset(DateTime) constructor alongside implicit conversion

[Copilot]

Plan for INTL0202 - Also flag DateTimeOffset(DateTime) constructor

• Understand current INTL0202 analyzer implementation
  • Review BanImplicitDateTimeToDateTimeOffsetConversion.cs
  • Review existing tests in DateTimeConversionTests.cs
  • Confirm Microsoft documentation on DateTimeOffset constructors
• Extend analyzer to detect DateTimeOffset(DateTime) constructor usage
  • Register operation action for ObjectCreation operations
  • Check if the created type is DateTimeOffset
  • Check if constructor has exactly 1 parameter of type DateTime
  • Report diagnostic when match is found
• Add tests for the new functionality
  • Test that flags new DateTimeOffset(DateTime.Now)
  • Test that flags new DateTimeOffset(new DateTime(...))
  • Test that does NOT flag new DateTimeOffset(DateTime.Now, TimeSpan.Zero)
  • Test that does NOT flag other DateTimeOffset constructors
• Run existing tests to ensure no regression
• Build and test the solution
• Request code review
  • Address code review feedback (removed trailing whitespace)
  • Address PR review feedback (throw instead of return on null types)
• Run CodeQL security checks

Summary

Successfully extended the INTL0202 analyzer to detect and flag usage of the DateTimeOffset(DateTime) constructor. Updated implementation to throw exceptions when fundamental types cannot be found, per code review feedback. All tests pass (7 DateTimeConversion tests, 78 total tests passing).

Original prompt

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This section details on the original issue you should resolve

<issue_title>INTL0202 - Also flag when the DateTime only Constructor of DateTimeOffset is used</issue_title>
<issue_description>Right now it flags on the implicit conversion of DT to DTO but you could mistakingly get around this by doing DateTimeOffset dto = new DateTimeOffset(new DateTime(2,2,2022)); and not including a timespan in your constructor when this is doing the same thing.</issue_description>

<agent_instructions>https://learn.microsoft.com/en-us/visualstudio/code-quality/roslyn-analyzers-overview?view=vs-2022

https://github.com/dotnet/roslyn/blob/main/docs/wiki/How-To-Write-a-C%23-Analyzer-and-Code-Fix.md

and any other docs you can find in microsoft learn about writing analyzers</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes INTL0202 - Also flag when the DateTime only Constructor of DateTimeOffset is used #302

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[BenjaminMichaelis]

@copilot Review the PR comments

[Copilot]

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