During LDM discussion on records, there was interest to have an analyzer warn on lower-cased type names. The motivation is that knowing that we discourage lower-cased type names would allow us to introduce new keywords (like record) with less concern about the breaking change.

I'm not sure whether this should be done by the compiler, a roslyn analyzer or some BCL analyzer.

Design:

• We use char.IsLower(...) for lower-case check.
• @ prefix avoids warning.
• All named types, included delegate types, are checked.
• Type and namespace aliases are checked too.

FYI @mikadumont @jmarolf