Parameter names in target-typed new() expressions are missing among completions in compound assignment statements

[Peter-Juhasz]

Version Used: VS 17.11.0 P 1.1

Steps to Reproduce:

List<int> list = null;
list ??= new($$);

Rogzites.2024-06-07.194355.mp4

Other observations:

• assignment expressions (list = new($$)) seem to work well
• but other compound assignment statements (list += new($$), -=, ...) reproduce the issue too
• method invocations seem to work as well too (list += Math.Abs($$))

Diagnostic Id: N/A

Expected Behavior:
Parameter names are listed.

Actual Behavior:
Parameter names are missing.

[DoctorKrolic]

@CyrusNajmabadi I debugged this case and it seems to be a compiler problem. It fails to identify type of new() if it has unbound identifier in it. Thus if you directly invoke completions in new($$) you get capacity, but if you type compiler starts returning error type for the expressio, so capacity disappears from the list. We can also observe that in the IDE by hovering over new: if the parameter list is empty hover correctly shows information about constructor, but if there is unbound identifier in parameter list, hover is no longer shown. Overall demo:

For comparison, here is how things work with normal assignment:

[CyrusNajmabadi]

@jcouv @jaredpar who is a good person to look into binding of implicit object creation expressions?