Version Used: VS 15.8.8 (Roslyn 2.9.0.63208)

Steps to Reproduce:

1. Paste the following code into a C# file.
2. Invoke the completion list at the marked location.

void M<T>() where T : $$

Expected Behavior: Only valid keywords (class, new, struct, unmanaged), valid types (classes, interfaces), other generic types, and namespaces appear in the list.

Actual Behavior: Of the allowed keywords, only new and unmanaged appear in the list. On the other hand, the list does include snippets, as well as struct, delegate and enum types, none of which are (as of C# 7.3) valid constraint types.