Short-circuiting null check operator

[HosseinYousefi]

Currently, instead of doing

a == null ? null : b

We can do

a ?? b

And instead of doing

a == null ? null : a.method()

We can do

a?.method()

However, we can't do this for other expressions, like function calls.

a == null ? null : f(a)

I propose a short-circuiting null check operator, so we can change the previous to this

f(??a)

Or convert this

a == null ? null : b == null ? null : a + b

into

??a + ??b

It can also be short-circuiting so in this example if f() is null then g won't be called:

??f() + ??g()

The operator itself doesn't have to be double question marks.

[eernstg]

Note that the following proposals touch upon a similar topic: null-aware-expressions Issues proposing new expressions to manage null .

[lrhn]

Specifically issue #1592, which even tries to summarize all the other ideas.

[munificent]

I'm going to go ahead and close this in favor of the other related issue and label.