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Improve pushing to Node::dependents.

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This patch makes it impossible for a node to end up in both
`node.parent` and `node.dependents`.
This commit is contained in:
Nicholas Nethercote 2018-06-07 15:35:10 +10:00
parent 2b973e6532
commit 6151bab8e1
1 changed files with 9 additions and 6 deletions
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15
src/librustc_data_structures/obligation_forest/mod.rs
View file

@ -193,15 +193,18 @@ impl<O: ForestObligation> ObligationForest<O> {
Entry::Occupied(o) => {
debug!("register_obligation_at({:?}, {:?}) - duplicate of {:?}!",
obligation, parent, o.get());
let node = &mut self.nodes[o.get().get()];
if let Some(parent) = parent {
if self.nodes[o.get().get()].dependents.contains(&parent) {
debug!("register_obligation_at({:?}, {:?}) - duplicate subobligation",
obligation, parent);
} else {
self.nodes[o.get().get()].dependents.push(parent);
// If the node is already in `waiting_cache`, it's already
// been marked with a parent. (It's possible that parent
// has been cleared by `apply_rewrites`, though.) So just
// dump `parent` into `node.dependents`... unless it's
// already in `node.dependents` or `node.parent`.
if !node.dependents.contains(&parent) && Some(parent) != node.parent {
node.dependents.push(parent);
}
}
if let NodeState::Error = self.nodes[o.get().get()].state.get() {
if let NodeState::Error = node.state.get() {
Err(())
} else {
Ok(())