variants

[David Strubbe]

On Mon, Apr 11, 2016 at 4:42 PM, Daniel J. Luke <dluke at geeklair.net> wrote:
>
> The ideal port has no variants (or at least has only default variants) -
> it builds with all reasonable options and people don't have to think about
> it.
>

I agree, but the question is what to do when the port does have variants.
Consider, for example, ports with Fortran compiler variants that enable
optional Fortran support, such as fftw-3. The current typical situation is
that a port requiring fftw-3 with Fortran will waste time installing the
default fftw-3 without Fortran, then give an error that it should have been
installed with Fortran. By contrast, if the default variant could be passed
on, fftw-3 would be installed with the needed Fortran support in the first
place.


>
> The dependency engine doesn't really handle variants - if it did, then I
> suppose it could make sense to pass default variants down.
>

I would say, on the contrary: if it did handle variants, it would be
unnecessary to pass variants down, because we would know automatically what
variants were needed. Since the dependency engine does not consider them,
that is why it would be very helpful to pass them down as it would solve
many of the issues about "dependency on a variant" that are always being
complained about on this list (such as the scenario I describe above).
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