Remove tracking of inferred dependency conflicts (#15909)

Alternative to #15884 (see commentary there)

Closes https://github.com/astral-sh/uv/issues/15869

crates/uv-pypi-types/src/conflicts.rs

@@ -95,16 +95,14 @@ impl Conflicts {
         let mut substitutions: FxHashMap<Rc<ConflictItem>, FxHashSet<Rc<ConflictItem>>> =
             FxHashMap::default();
 
-        // Conflict sets that were directly defined in configuration.
+        // Track all existing conflict sets to avoid duplicates.
-        let mut direct_conflict_sets: FxHashSet<&ConflictSet> = FxHashSet::default();
+        let mut conflict_sets: FxHashSet<ConflictSet> = FxHashSet::default();
-        // Conflict sets that we will transitively infer in this method.
-        let mut transitive_conflict_sets: FxHashSet<ConflictSet> = FxHashSet::default();
 
         // Add groups in directly defined conflict sets to the graph.
         let mut seen: FxHashSet<&GroupName> = FxHashSet::default();
 
         for set in &self.0 {
-            direct_conflict_sets.insert(set);
+            conflict_sets.insert(set.clone());
             for item in set.iter() {
                 let ConflictKind::Group(group) = &item.kind else {
                     // TODO(john): Do we also want to handle extras here?
@@ -183,28 +181,30 @@ impl Conflicts {
         // at the end of each iteration.
         for (canonical_item, subs) in substitutions {
             let mut new_conflict_sets = FxHashSet::default();
-            for conflict_set in direct_conflict_sets
+            for conflict_set in conflict_sets
                 .iter()
-                .copied()
-                .chain(transitive_conflict_sets.iter())
                 .filter(|set| set.contains_item(&canonical_item))
+                .cloned()
+                .collect::<Vec<_>>()
             {
                 for sub in &subs {
-                    let mut new_set = conflict_set
+                    let new_set = conflict_set
                         .replaced_item(&canonical_item, (**sub).clone())
                         .expect("`ConflictItem` should be in `ConflictSet`");
-                    if !direct_conflict_sets.contains(&new_set) {
+                    if !conflict_sets.contains(&new_set) {
-                        new_set = new_set.with_inferred_conflict();
+                        new_conflict_sets.insert(new_set);
-                        if !transitive_conflict_sets.contains(&new_set) {
-                            new_conflict_sets.insert(new_set);
-                        }
                     }
                 }
             }
-            transitive_conflict_sets.extend(new_conflict_sets.into_iter());
+            conflict_sets.extend(new_conflict_sets.into_iter());
         }
 
-        self.0.extend(transitive_conflict_sets);
+        // Add all newly discovered conflict sets (excluding the originals already in self.0)
+        for set in conflict_sets {
+            if !self.0.contains(&set) {
+                self.0.push(set);
+            }
+        }
     }
 }
 
@@ -220,7 +220,6 @@ impl Conflicts {
 #[derive(Debug, Default, Clone, Hash, Eq, PartialEq)]
 pub struct ConflictSet {
     set: BTreeSet<ConflictItem>,
-    is_inferred_conflict: bool,
 }
 
 impl ConflictSet {
@@ -228,7 +227,6 @@ impl ConflictSet {
     pub fn pair(item1: ConflictItem, item2: ConflictItem) -> Self {
         Self {
             set: BTreeSet::from_iter(vec![item1, item2]),
-            is_inferred_conflict: false,
         }
     }
 
@@ -255,11 +253,6 @@ impl ConflictSet {
         self.set.contains(conflict_item)
     }
 
-    /// This [`ConflictSet`] was inferred from directly defined conflicts.
-    pub fn is_inferred_conflict(&self) -> bool {
-        self.is_inferred_conflict
-    }
-
     /// Replace an old [`ConflictItem`] with a new one.
     pub fn replaced_item(
         &self,
@@ -272,17 +265,7 @@ impl ConflictSet {
         }
         new_set.remove(old);
         new_set.insert(new);
-        Ok(Self {
+        Ok(Self { set: new_set })
-            set: new_set,
-            is_inferred_conflict: false,
-        })
-    }
-
-    /// Mark this [`ConflictSet`] as being inferred from directly
-    /// defined conflicts.
-    fn with_inferred_conflict(mut self) -> Self {
-        self.is_inferred_conflict = true;
-        self
     }
 }
 
@@ -307,7 +290,6 @@ impl TryFrom<Vec<ConflictItem>> for ConflictSet {
         }
         Ok(Self {
             set: BTreeSet::from_iter(items),
-            is_inferred_conflict: false,
         })
     }
 }

crates/uv/src/commands/project/mod.rs

@@ -320,14 +320,9 @@ impl std::fmt::Display for ConflictError {
             .iter()
             .all(|conflict| matches!(conflict.kind(), ConflictKind::Group(..)))
         {
-            let conflict_source = if self.set.is_inferred_conflict() {
-                "transitively inferred"
-            } else {
-                "declared"
-            };
             write!(
                 f,
-                "Groups {} are incompatible with the {conflict_source} conflicts: {{{set}}}",
+                "Groups {} are incompatible with the conflicts: {{{set}}}",
                 conjunction(
                     self.conflicts
                         .iter()

crates/uv/tests/it/lock_conflict.rs

@@ -2072,7 +2072,7 @@ fn group_basic() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-    error: Groups `group1` and `group2` are incompatible with the declared conflicts: {`project:group1`, `project:group2`}
+    error: Groups `group1` and `group2` are incompatible with the conflicts: {`project:group1`, `project:group2`}
     "###);
 
     Ok(())
@@ -2217,7 +2217,7 @@ fn group_default() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-    error: Groups `group1` (enabled by default) and `group2` are incompatible with the declared conflicts: {`project:group1`, `project:group2`}
+    error: Groups `group1` (enabled by default) and `group2` are incompatible with the conflicts: {`project:group1`, `project:group2`}
     "###);
 
     // If the group is explicitly requested, we should still fail, but shouldn't mark it as
@@ -2228,7 +2228,7 @@ fn group_default() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-    error: Groups `group1` and `group2` are incompatible with the declared conflicts: {`project:group1`, `project:group2`}
+    error: Groups `group1` and `group2` are incompatible with the conflicts: {`project:group1`, `project:group2`}
     "###);
 
     // If we install via `--all-groups`, we should also avoid marking the group as "enabled by
@@ -2239,7 +2239,7 @@ fn group_default() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-    error: Groups `group1` and `group2` are incompatible with the declared conflicts: {`project:group1`, `project:group2`}
+    error: Groups `group1` and `group2` are incompatible with the conflicts: {`project:group1`, `project:group2`}
     "###);
 
     // Disabling the default group should succeed.

crates/uv/tests/it/sync.rs

@@ -11038,7 +11038,7 @@ fn multiple_group_conflicts() -> Result<()> {
 
     ----- stderr -----
     Resolved 3 packages in [TIME]
-    error: Groups `bar` and `foo` are incompatible with the declared conflicts: {`project:bar`, `project:foo`}
+    error: Groups `bar` and `foo` are incompatible with the conflicts: {`project:bar`, `project:foo`}
     ");
 
     Ok(())
@@ -11075,6 +11075,24 @@ fn transitive_group_conflicts_shallow() -> Result<()> {
         "#,
     )?;
 
+    uv_snapshot!(context.filters(), context.lock(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 5 packages in [TIME]
+    ");
+
+    uv_snapshot!(context.filters(), context.lock().arg("--check"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 5 packages in [TIME]
+    ");
+
     uv_snapshot!(context.filters(), context.sync(), @r"
     success: true
     exit_code: 0
@@ -11116,7 +11134,7 @@ fn transitive_group_conflicts_shallow() -> Result<()> {
 
     ----- stderr -----
     Resolved 5 packages in [TIME]
-    error: Groups `magic` and `test` are incompatible with the declared conflicts: {`example:magic`, `example:test`}
+    error: Groups `magic` and `test` are incompatible with the conflicts: {`example:magic`, `example:test`}
     ");
 
     uv_snapshot!(context.filters(), context.sync().arg("--group").arg("dev").arg("--group").arg("magic"), @r"
@@ -11126,7 +11144,7 @@ fn transitive_group_conflicts_shallow() -> Result<()> {
 
     ----- stderr -----
     Resolved 5 packages in [TIME]
-    error: Groups `dev` and `magic` are incompatible with the transitively inferred conflicts: {`example:dev`, `example:magic`}
+    error: Groups `dev` and `magic` are incompatible with the conflicts: {`example:dev`, `example:magic`}
     ");
 
     Ok(())
@@ -11213,7 +11231,7 @@ fn transitive_group_conflicts_deep() -> Result<()> {
 
     ----- stderr -----
     Resolved 7 packages in [TIME]
-    error: Groups `dev` and `magic` are incompatible with the transitively inferred conflicts: {`example:dev`, `example:magic`}
+    error: Groups `dev` and `magic` are incompatible with the conflicts: {`example:dev`, `example:magic`}
     ");
 
     uv_snapshot!(context.filters(), context.sync().arg("--no-dev").arg("--group").arg("intermediate").arg("--group").arg("magic"), @r"
@@ -11223,7 +11241,7 @@ fn transitive_group_conflicts_deep() -> Result<()> {
 
     ----- stderr -----
     Resolved 7 packages in [TIME]
-    error: Groups `intermediate` and `magic` are incompatible with the transitively inferred conflicts: {`example:intermediate`, `example:magic`}
+    error: Groups `intermediate` and `magic` are incompatible with the conflicts: {`example:intermediate`, `example:magic`}
     ");
 
     Ok(())
@@ -11307,7 +11325,7 @@ fn transitive_group_conflicts_siblings() -> Result<()> {
 
     ----- stderr -----
     Resolved 5 packages in [TIME]
-    error: Groups `dev` (enabled by default) and `dev2` are incompatible with the transitively inferred conflicts: {`example:dev`, `example:dev2`}
+    error: Groups `dev` (enabled by default) and `dev2` are incompatible with the conflicts: {`example:dev`, `example:dev2`}
     ");
 
     uv_snapshot!(context.filters(), context.sync().arg("--group").arg("dev").arg("--group").arg("dev2"), @r"
@@ -11317,7 +11335,7 @@ fn transitive_group_conflicts_siblings() -> Result<()> {
 
     ----- stderr -----
     Resolved 5 packages in [TIME]
-    error: Groups `dev` and `dev2` are incompatible with the transitively inferred conflicts: {`example:dev`, `example:dev2`}
+    error: Groups `dev` and `dev2` are incompatible with the conflicts: {`example:dev`, `example:dev2`}
     ");
 
     Ok(())