From 45a8f37b6ae230db6c30c013f17d8aebac98a5e1 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Tue, 23 Mar 2021 12:49:55 +0300
Subject: Compute more mathematically well-rounded notion of transitive deps

By including the crate itself, we make the resulting set closed with
respect to `transitve_reveres_dependencies` operation, as it becomes a
proper transitive closure. This just feels more proper and mathy.

And, indeed, this actually allows us to simplify call sites somewhat.
---
 crates/base_db/src/input.rs | 4 +++-
 crates/hir/src/lib.rs       | 3 +--
 crates/ide_db/src/search.rs | 4 +---
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/crates/base_db/src/input.rs b/crates/base_db/src/input.rs
index e9e8dfc2e..248ab1de2 100644
--- a/crates/base_db/src/input.rs
+++ b/crates/base_db/src/input.rs
@@ -274,13 +274,15 @@ impl CrateGraph {
         deps.into_iter()
     }
 
-    /// Returns an iterator over all transitive reverse dependencies of the given crate.
+    /// Returns all transitive reverse dependencies of the given crate,
+    /// including the crate itself.
     pub fn transitive_reverse_dependencies(
         &self,
         of: CrateId,
     ) -> impl Iterator<Item = CrateId> + '_ {
         let mut worklist = vec![of];
         let mut rev_deps = FxHashSet::default();
+        rev_deps.insert(of);
         let mut inverted_graph = FxHashMap::<_, Vec<_>>::default();
         self.arena.iter().for_each(|(&krate, data)| {
             data.dependencies
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 30b96d7e2..aefebde06 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -1572,8 +1572,7 @@ impl Impl {
     pub fn all_for_trait(db: &dyn HirDatabase, trait_: Trait) -> Vec<Impl> {
         let krate = trait_.module(db).krate();
         let mut all = Vec::new();
-        for Crate { id } in krate.transitive_reverse_dependencies(db).into_iter().chain(Some(krate))
-        {
+        for Crate { id } in krate.transitive_reverse_dependencies(db).into_iter() {
             let impls = db.trait_impls_in_crate(id);
             all.extend(impls.for_trait(trait_.id).map(Self::from))
         }
diff --git a/crates/ide_db/src/search.rs b/crates/ide_db/src/search.rs
index 324817cd0..8e93de277 100644
--- a/crates/ide_db/src/search.rs
+++ b/crates/ide_db/src/search.rs
@@ -245,9 +245,7 @@ impl Definition {
         }
 
         if let Some(Visibility::Public) = vis {
-            let source_root_id = db.file_source_root(file_id);
-            let source_root = db.source_root(source_root_id);
-            let mut res = source_root.iter().map(|id| (id, None)).collect::<FxHashMap<_, _>>();
+            let mut res = FxHashMap::default();
 
             let krate = module.krate();
             for rev_dep in krate.transitive_reverse_dependencies(db) {
-- 
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