gcc 4.9.3: typedef referenced in a friend template function

[Jonathan Wakely]

On 22 September 2015 at 13:20, Francis ANDRE wrote:
> What is the meaning of: ISO C++ forbids declaration of ‘type name’ with no
> type?

It means you need to say static_cast<const typename
Alphabetic<size>::DataType&>(a) because DataType is a dependent type.