Should Convert.ChangeType handle unions especially?

[Youssef1313]

For example:

Console.WriteLine(Convert.ChangeType("Hello", typeof(MyUnion)));

union MyUnion(string, int);

This throws InvalidCastException today.

[tannergooding]

Convert is largely a legacy API. It (barring the To/FromBase64 APIs) only works with IConvertible (and therefore TypeCode) which is incredibly limited and not readily versionable.

In most cases you're better off using IParsable, IFormattable, or one of the INumberBase.CreateChecked/Truncating/Saturating APIs which covers all the same scenarios Convert+IConvertible handled plus more in an extensible fashion.

So to answer the question, no it should likely not handle unions and I am doubtful we will be touching the code to handle any new types in the future.

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