pub fn dataflow_attr(attr: &Attribute) -> Option<(Attribute, Option<String>)>Expand description
Unwrap a #[dataflow] attribute, including any #[cfg_attr(...)] wrapper.
Returns the inner #[dataflow] attribute and the combined cfg predicate,
or None for non-dataflow attributes. A bare #[dataflow] returns the
attribute and None; nested cfg_attr predicates are folded into
all(outer, inner).
Who needs the unwrap: everything that reads attributes as written. The
compiler applies cfg_attr before #[dataflow] itself runs, but the
#[dataflow_bundle] macro receives its module’s member fns with their
attributes untouched, and the textual scanners (scan_dataflow, the
tools crate) read source. The predicate is how a wrapped fn’s accesses
keep the cfg they are conditional on, as a #[cfg] on the fn would.