I’m using Visual Studio 2022 _{(with ReSharper 2024.1 but I don’t think that’s relevant)} developing in .NET 8. My minimal repro is this: I have a DataTable object named dataTable, and these two lines of code:

var err = (
    from DataRow r in dataTable.Rows 
    select (r.Field<string>(0), r.Field<string>(1))
).First();

var wut = (
    dataTable.Rows.Cast<DataRow>()
    .Select(r => (r.Field<string>(0), r.Field<string>(1)))
).First();

My understanding is that the LINQ query-syntax style (from … select) seen in err is simply ‘syntactic sugar’ for the actual method calls seen in wut. I asked ReSharper to convert the first to the second; but I agree with what it’s done. Both lines, I thought, would do the same thing: get the first row of dataTable, pull out the first two columns as strings, and put those strings into a tuple. Therefore, I would expect err and wut to have the same inferred type.

But they don’t.

err is a (string, string) , whereas wut is a (string?, string?).

What am I missing? Is this a failure of my expectation, a failure of ReSharper’s query-syntax-to-method-chain conversion, or something else?