allow conditional operator to infer foo? when something ? foo : null

[gdr2333]

Take a look at this code:

var condition = /* something */ ;
var number = 123;
var want = condition ? number : null;

I think it's reasonable to extrapolate the return type of that expression as int?, and null here should be treated as (int?)null, and when changing to var want = condition ? number : (int?)null, it can be compiled.

But no, we have CS0173:

Type of conditional expression cannot be determined because there is no implicit conversion between 'int' and '<null>'

It's not a big problem, but I think we can improve on this. Actually my thoughts are unified 'condition?' foo: null' works when foo is a value type and foo is a reference type. Because of the following code:

var condition = /* something */ ;
var uri = new Uri("https://microsoft.com");
var want = condition ? uri : null;

can be compiled, and want is inferred as a Uri?.

[333fred]

Duplicate of #33.

[gdr2333]

sorry.