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Auto merge of #17457 - roife:remove-circle, r=Veykril
fix: ensure there are no cycles in the source_root_parent_map
See #17409
We can view the connections between roots as a graph. The problem is that this graph may contain cycles, so when adding edges, it is necessary to check whether it will lead to a cycle.
Since we ensure that each node has at most one outgoing edge (because each SourceRoot can have only one parent), we can use a disjoint-set to maintain the connectivity between nodes. If an edge’s two nodes belong to the same set, they are already connected.
Additionally, this PR includes the following three changes:
1. Removed the workaround from #17409.
2. Added an optimization: If `map.contains_key(&SourceRootId(*root_id as u32))`, we can skip the current loop iteration since we have already found its parent.
3. Modified the inner loop to iterate in reverse order with `roots[..idx].iter().rev()` at line 319. This ensures that if we are looking for the parent of `a/b/c`, and both `a` and `a/b` meet the criteria, we will choose the longer match (`a/b`).
| -rw-r--r-- | crates/load-cargo/src/lib.rs | 84 | ||||
| -rw-r--r-- | crates/rust-analyzer/src/config.rs | 9 |
2 files changed, 63 insertions, 30 deletions
diff --git a/crates/load-cargo/src/lib.rs b/crates/load-cargo/src/lib.rs index cb785195a0..de68b86714 100644 --- a/crates/load-cargo/src/lib.rs +++ b/crates/load-cargo/src/lib.rs @@ -285,28 +285,54 @@ impl SourceRootConfig { /// If a `SourceRoot` doesn't have a parent and is local then it is not contained in this mapping but it can be asserted that it is a root `SourceRoot`. pub fn source_root_parent_map(&self) -> FxHashMap<SourceRootId, SourceRootId> { let roots = self.fsc.roots(); - roots - .iter() - .enumerate() - .filter(|(_, (_, id))| self.local_filesets.contains(id)) - .filter_map(|(idx, (root, root_id))| { - // We are interested in parents if they are also local source roots. - // So instead of a non-local parent we may take a local ancestor as a parent to a node. - // - // Here paths in roots are sorted lexicographically, so if a root - // is a parent of another root, it will be before it in the list. - roots[..idx].iter().find_map(|(root2, root2_id)| { - if self.local_filesets.contains(root2_id) - && root.starts_with(root2) - && root_id != root2_id - { - return Some((root_id, root2_id)); + + let mut map = FxHashMap::default(); + + // See https://github.com/rust-lang/rust-analyzer/issues/17409 + // + // We can view the connections between roots as a graph. The problem is + // that this graph may contain cycles, so when adding edges, it is necessary + // to check whether it will lead to a cycle. + // + // Since we ensure that each node has at most one outgoing edge (because + // each SourceRoot can have only one parent), we can use a disjoint-set to + // maintain the connectivity between nodes. If an edge’s two nodes belong + // to the same set, they are already connected. + let mut dsu = FxHashMap::default(); + fn find_parent(dsu: &mut FxHashMap<u64, u64>, id: u64) -> u64 { + if let Some(&parent) = dsu.get(&id) { + let parent = find_parent(dsu, parent); + dsu.insert(id, parent); + parent + } else { + id + } + } + + for (idx, (root, root_id)) in roots.iter().enumerate() { + if !self.local_filesets.contains(root_id) + || map.contains_key(&SourceRootId(*root_id as u32)) + { + continue; + } + + for (root2, root2_id) in roots[..idx].iter().rev() { + if self.local_filesets.contains(root2_id) + && root_id != root2_id + && root.starts_with(root2) + { + // check if the edge will create a cycle + if find_parent(&mut dsu, *root_id) != find_parent(&mut dsu, *root2_id) { + map.insert(SourceRootId(*root_id as u32), SourceRootId(*root2_id as u32)); + dsu.insert(*root_id, *root2_id); } - None - }) - }) - .map(|(&child, &parent)| (SourceRootId(child as u32), SourceRootId(parent as u32))) - .collect() + + break; + } + } + } + + map } } @@ -592,4 +618,20 @@ mod tests { assert_eq!(vc, vec![(SourceRootId(1), SourceRootId(0)),]) } + + #[test] + fn circular_reference() { + let mut builder = FileSetConfigBuilder::default(); + builder.add_file_set(vec![ + VfsPath::new_virtual_path("/ROOT/def".to_owned()), + VfsPath::new_virtual_path("/ROOT/def/abc/def".to_owned()), + ]); + builder.add_file_set(vec![VfsPath::new_virtual_path("/ROOT/def/abc".to_owned())]); + let fsc = builder.build(); + let src = SourceRootConfig { fsc, local_filesets: vec![0, 1] }; + let mut vc = src.source_root_parent_map().into_iter().collect::<Vec<_>>(); + vc.sort_by(|x, y| x.0 .0.cmp(&y.0 .0)); + + assert_eq!(vc, vec![(SourceRootId(1), SourceRootId(0)),]) + } } diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs index ef890fa3e6..e8504979be 100644 --- a/crates/rust-analyzer/src/config.rs +++ b/crates/rust-analyzer/src/config.rs @@ -2531,7 +2531,6 @@ macro_rules! _impl_for_config_data { #[allow(non_snake_case)] $vis fn $field(&self, source_root: Option<SourceRootId>) -> &$ty { let mut par: Option<SourceRootId> = source_root; - let mut traversals = 0; while let Some(source_root_id) = par { par = self.source_root_parent_map.get(&source_root_id).copied(); if let Some((config, _)) = self.ratoml_files.get(&source_root_id) { @@ -2539,14 +2538,6 @@ macro_rules! _impl_for_config_data { return value; } } - // Prevent infinite loops caused by cycles by giving up when it's - // clear that we must have either visited all source roots or - // encountered a cycle. - traversals += 1; - if traversals >= self.source_root_parent_map.len() { - // i.e. no source root contains the config we're looking for - break; - } } if let Some((root_path_ratoml, _)) = self.root_ratoml.as_ref() { |