def spec_versions(self, spec):
    "Return list of clauses expressing spec's version constraints."
    spec = specify(spec)
    assert spec.name
    if spec.concrete:
        return [fn.version(spec.name, spec.version)]
    if (spec.versions == spack.version.ver(':')):
        return []
    self.version_constraints.add((spec.name, spec.versions))
    return [fn.version_satisfies(spec.name, spec.versions)]
Return list of clauses expressing spec's version constraints.
def spec_versions(self, spec):
    
    spec = specify(spec)
    assert spec.name
    if spec.concrete:
        return [fn.version(spec.name, spec.version)]
    if (spec.versions == spack.version.ver(':')):
        return []
    self.version_constraints.add((spec.name, spec.versions))
    return [fn.version_satisfies(spec.name, spec.versions)]