Types through a macro

[Kaba]

Here, the keyword "typename" is not allowed, since main is not a
template. However, the "typename" is required if Result was in fact a
dependent name to use the DEDUCTION macro in a context where typename
was required, for instance in:

You are right. I initially took this example out of its real context
(where there are always dependent names) to simplify and then
accidentally introduced the problem you describe. Good catch.