Todd Gamblin 0620d954f5 concretizer: don't generate rules for empty version lists ...

If the version list passed to one_of_iff is empty, it still generates a
rule like this:

    node_compiler_version_satisfies("fujitsu-mpi", "arm", ":") :- 1 {  } 1.
    1 {  } 1 :- node_compiler_version_satisfies("fujitsu-mpi", "arm", ":").

The cardinality rules on the right and left above are never
satisfiale, and these rules do nothing.

- [x] Skip generating any rules at all for empty version lists.

2020-11-17 10:04:13 -08:00

..

spack

concretizer: don't generate rules for empty version lists

2020-11-17 10:04:13 -08:00