message: macros: add ast::Arm beginning_vert
diff: @@ -159,6 +159,7 @@ fn cs_from(name: &str, cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure
  pats: vec!(cx.pat_wild(span)),
  guard: Some(guard),
  body: body,
  + beginning_vert: None,
  };
  arms.push(arm);
  @@ -186,6 +187,7 @@ fn cs_from(name: &str, cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure
  pats: vec!(cx.pat_wild(trait_span)),
  guard: None,
  body: cx.expr_none(trait_span),
  + beginning_vert: None,
  };
  arms.push(arm);
  