private DiagnosticInfo DeriveUseSiteDiagnosticFromBase() { NamedTypeSymbol @base = this.BaseTypeNoUseSiteDiagnostics; while ((object)@base != null) { if (@base.IsErrorType() && @base is NoPiaIllegalGenericInstantiationSymbol) { return(@base.GetUseSiteDiagnostic()); } @base = @base.BaseTypeNoUseSiteDiagnostics; } return(null); }