This provides a more robust way of checking from where
the original expressions are coming from compared to the
lexical check_clauses field we had in elixir_scope.
A direct consequence of this commit is that, the following
code:
defrecord Sample, [:hello] do
import List
end
Now raises a warning if the List import is not used,
where it didn't previously.
This means the second item in the AST is no longer an integer
(representing the line), but a keywords list. Code that relies
on the line information from AST or that manually generate AST
nodes need to be properly updated.
José Valim