I upgraded from v0.5 to v0.6 and using a comprehension in a generated function gives the following error:

generated function body is not pure. this likely means it contains a closure or comprehension.

The following is a minimum working example:

```
@generated function _test{T,N}(s::AbstractArray{T,N})
:([1 for i=1:size(s,2)])
end
a = ones(1,2)
b=_test(a)
```

and leads to the expected result in v0.5, but gives the following error in v0.6:

generated function body is not pure. this likely means it contains a closure or comprehension.

It seems to me that the comprehension [… for … ] is the problem.

Is this a planned deprecation or a bug? If this is a planned depreciation, how to get around it?

(For reference, the error occurs in the TimeWarp.jl package, dba.jl, l.147)

Thanks