True when Directives is a list of directives that appear in the
source file File. Reading directives stops at the first
non-directive term. Processing deals with expand_term/2 as well as
conditional compilation. Options processed:
canonical_source(-Source)
Unify Source with the canonical source identifier as also
used by library(prolog_xref).
silent(+Boolean)
If true (default false), do not report syntax errors and
other errors.