Why does this (null || !TryParse) conditional result in “use of unassigned local variable”?

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I am pretty sure this is a compiler bug. Nice find!

Edit: it is not a bug, as Quartermeister demonstrates; dynamic might implement a weird true operator which might cause y to never be initialized.

Here’s a minimal repro:

class Program
{
    static bool M(out int x) 
    { 
        x = 123; 
        return true; 
    }
    static int N(dynamic d)
    {
        int y;
        if(d || M(out y))
            y = 10;
        return y; 
    }
}

I see no reason why that should be illegal; if you replace dynamic with bool it compiles just fine.

I’m actually meeting with the C# team tomorrow; I’ll mention it to them. Apologies for the error!

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