Proposal: Extend null-conditional (?., ?[]) and null-coalescing (??) operators to pointers

[YaakovDavis]

I'd like to be able to write:

Data* p = GetUnmanagedData();
p?->Act();
var a = p?->X ?? 42;
var b = p?[3] ?? new Data();
var p2 = p ?? AnotherDataPointer();

The above should compile to the equivalent of the following:

Data* p = GetUnmanagedData();
if(p != null)
   p->Act();

var a = p != null ? p->X : 42;
var b = p != null ? p[3] : new Data();
var p2 = p != null ? p : AnotherDataPointer();

[svick]

This is half of a duplicate of #323.

[YaakovDavis]

@svick
I thought I had encountered something similar, but couldn't find it.
In any case, this proposal is more encompassing.

[jacekbe]

When I proposed #323 I completely forgot about null-conditional operators. Obviously it would be nice if both null-conditional and null-coalescing operator worked also for pointer types.

Note that null-coalescing operator is already supported by VS2017 quick actions. VS2017 hints that it could be simplified to use null-coalescing operator even though resulting code does not compile.

 unsafe byte* SomeFunc(byte* p, byte* defaultVal)
 {
      return p != null ? p : defaultVal;            
 }

[gafter]

I've queued this to be considered by the LDM at #418.

[gafter]

@lachbaer The LDM discussed this today and we decided that while it isn't something we would devote resources to implementing, we'd probably accept a contributed implementation along with #418.