class A { }
public class B<T> { }
public class C : B<A> { }

Currently, the error is:

Severity Code    Description
Error    CS0060  Inconsistent accessibility: base class 'B<A>' is less accessible than class 'C'

This isn't great wording. It's the type argument of the base class that's less accessible, but the wording implies that it's B<T> itself that's less accessible. The error should explicitly call out the type argument as the thing not accessible.

If someone from the community is interested in improving this, a change would need to be made around here: https://github.com/dotnet/roslyn/blob/master/src/Compilers/CSharp/Portable/Symbols/Source/SourceNamedTypeSymbol_Bases.cs#L316-L320, splitting this up into multiple checks.