forcing local build from a package definition

[Federico Beffa <beffa@ieee.org>]

Hi,

I'm preparing a package for ATLAS (Automatically Tuned Linear Algebra
Software).  The library provides functions from LAPACK which are automatically
speed optimized for the hardware on which the library is built (the
optimization takes place during the build phase).

My question is the following: is there a way to force a local build from a
package definition (without having to pass '--no-substitutes' to guix)?

If not, what do you think about explicitly stating in the description of the
package that it MUST be installed with the '--no-substitutes' flag and, if the
user does not do so, hydra may provide a package which does not run on the
user hardware?

Most other distributions deliver binary packages which have been compiled for
a very general CPU.  However, this not satisfactory since it results in a much
slower library.  Guix is in a nice position to provide a good performance
version of the library and I think we should do so.

Regards,
Fede