1 //! Propagates [`#[doc(cfg(...))]`](https://github.com/rust-lang/rust/issues/43781) to child items.
4 use crate::clean::cfg::Cfg;
5 use crate::clean::inline::{load_attrs, merge_attrs};
6 use crate::clean::{Crate, Item};
7 use crate::core::DocContext;
8 use crate::fold::DocFolder;
9 use crate::passes::Pass;
11 use rustc_hir::def_id::LocalDefId;
13 pub(crate) const PROPAGATE_DOC_CFG: Pass = Pass {
14 name: "propagate-doc-cfg",
15 run: propagate_doc_cfg,
16 description: "propagates `#[doc(cfg(...))]` to child items",
19 pub(crate) fn propagate_doc_cfg(cr: Crate, cx: &mut DocContext<'_>) -> Crate {
20 CfgPropagator { parent_cfg: None, parent: None, cx }.fold_crate(cr)
23 struct CfgPropagator<'a, 'tcx> {
24 parent_cfg: Option<Arc<Cfg>>,
25 parent: Option<LocalDefId>,
26 cx: &'a mut DocContext<'tcx>,
29 impl<'a, 'tcx> DocFolder for CfgPropagator<'a, 'tcx> {
30 fn fold_item(&mut self, mut item: Item) -> Option<Item> {
31 let old_parent_cfg = self.parent_cfg.clone();
33 if item.kind.is_non_assoc() &&
34 let Some(def_id) = item.item_id.as_def_id().and_then(|def_id| def_id.as_local()) {
35 let hir = self.cx.tcx.hir();
36 let hir_id = hir.local_def_id_to_hir_id(def_id);
37 let expected_parent = hir.get_parent_item(hir_id);
39 // If parents are different, it means that `item` is a reexport and we need to compute
40 // the actual `cfg` by iterating through its "real" parents.
41 if self.parent != Some(expected_parent) {
42 let mut attrs = Vec::new();
43 for (parent_hir_id, _) in hir.parent_iter(hir_id) {
44 if let Some(def_id) = hir.opt_local_def_id(parent_hir_id) {
45 attrs.extend_from_slice(load_attrs(self.cx, def_id.to_def_id()));
49 merge_attrs(self.cx, None, item.attrs.other_attrs.as_slice(), Some(&attrs));
53 let new_cfg = match (self.parent_cfg.take(), item.cfg.take()) {
55 (Some(rc), None) | (None, Some(rc)) => Some(rc),
56 (Some(mut a), Some(b)) => {
57 let b = Arc::try_unwrap(b).unwrap_or_else(|rc| Cfg::clone(&rc));
58 *Arc::make_mut(&mut a) &= b;
62 self.parent_cfg = new_cfg.clone();
66 if let Some(def_id) = item.item_id.as_def_id().and_then(|def_id| def_id.as_local()) {
67 self.parent.replace(def_id)
71 let result = self.fold_item_recur(item);
72 self.parent_cfg = old_parent_cfg;
73 self.parent = old_parent;