Implicit conversion to System.Double with a nullable struct via compiler generated locals: why is this failing?

Question

Given the following, why does the InvalidCastException get thrown? I can\'t see why it should be outside of a bug (this is in x86; x64 crashes with a 0xC0000005 in clrjit.dll).<

Answer 1

This sure looks like a compiler bug to me. The IL suggests the compiler is generating code to convert the MyDouble? to a double with the conversion operator, then to a double?. But takes a nosedive when it then uses the conversion operator again on that double?. That's bad, wrong argument type. Nor is there a need.

This feedback article resembles this bug. Over 6 years old already, that must be a tricky part of the compiler. I do imagine it is.