Consider reporting a warning when a short-circuiting logic operator has a nullable boolean as its first operand

[AnthonyDGreen]

The spec says this:

In the lifted form of the AndAlso and OrElse operators, if the first operand was a null Boolean?, then the second operand is evaluated but the result is always a null Boolean?.

While that's logically consistent with the VB treatment of nullable Booleans it's somewhat contrary to the benefit of a short-circuiting operator and totally unintuitive. We should consider reporting a warning in such cases.

[Bill-McC]

• warning should provide link to guidance on how to achieve common tasks.
• warning should be on by default but easy to turn off (at IDE level (?))
• code correction candidates
• a little animated paperclip that says "it looks like you are trying to use AndAlso with a nullable Boolean .... "

Pick any 3 of the above 4 ;)

[AnthonyDGreen]

I'm in love with the paperclip already. I'm still on the fence about two of the other three :)

[jrmoreno1]

I would say the spec should be changed to read "and if the second operand needs to be evaluated the result..."

Which is consistent with what actually happens.

            Dim b As Boolean?
            Dim t As Boolean = true
            Dim combined As Boolean = b AndAlso t

fails with a compiler error, while both

            Dim b As Boolean?
            Dim t As Boolean = true
            Dim combined As Boolean = b OrElse t

And

            Dim b as Boolean? = true
            Dim combined As Boolean = b OrElse 1/0

succeeds. VB does the right thing in all cases, but it doesn’t look like the spec describes the correct result.