Avoid installing transitive dev dependencies (#7318)

## Summary

This is arguably breaking, arguably a bug... Today, if project A depends
on project B, and you install A with dev dependencies enabled, you also
get B's dev dependencies. I think this is incorrect. Just like you
shouldn't be importing B's dependencies from A, you shouldn't be using
B's dev dependencies when developing on A.

Closes #7310.

crates/uv-resolver/src/lock/mod.rs

@@ -575,6 +575,23 @@ impl Lock {
                     }
                 }
             }
+
+            // Add any dev dependencies.
+            for group in dev {
+                for dep in root.dev_dependencies.get(group).into_iter().flatten() {
+                    if dep.complexified_marker.evaluate(marker_env, &[]) {
+                        let dep_dist = self.find_by_id(&dep.package_id);
+                        if seen.insert((&dep.package_id, None)) {
+                            queue.push_back((dep_dist, None));
+                        }
+                        for extra in &dep.extra {
+                            if seen.insert((&dep.package_id, Some(extra))) {
+                                queue.push_back((dep_dist, Some(extra)));
+                            }
+                        }
+                    }
+                }
+            }
         }
 
         // Add any dependency groups that are exclusive to the workspace root (e.g., dev
@@ -606,16 +623,11 @@ impl Lock {
         let mut map = BTreeMap::default();
         let mut hashes = BTreeMap::default();
         while let Some((dist, extra)) = queue.pop_front() {
-            let deps =
+            let deps = if let Some(extra) = extra {
-                if let Some(extra) = extra {
+                Either::Left(dist.optional_dependencies.get(extra).into_iter().flatten())
-                    Either::Left(dist.optional_dependencies.get(extra).into_iter().flatten())
+            } else {
-                } else {
+                Either::Right(dist.dependencies.iter())
-                    Either::Right(dist.dependencies.iter().chain(
+            };
-                        dev.iter().flat_map(|group| {
-                            dist.dev_dependencies.get(group).into_iter().flatten()
-                        }),
-                    ))
-                };
             for dep in deps {
                 if dep.complexified_marker.evaluate(marker_env, &[]) {
                     let dep_dist = self.find_by_id(&dep.package_id);

crates/uv/tests/sync.rs

@@ -2248,3 +2248,83 @@ fn sync_wheel_path_source_error() -> Result<()> {
 
     Ok(())
 }
+
+/// Avoid installing dev dependencies of transitive dependencies.
+#[test]
+fn transitive_dev() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "root"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["child"]
+
+        [build-system]
+        requires = ["setuptools>=42"]
+        build-backend = "setuptools.build_meta"
+
+        [tool.uv]
+        dev-dependencies = ["anyio>3"]
+
+        [tool.uv.sources]
+        child = { workspace = true }
+
+        [tool.uv.workspace]
+        members = ["child"]
+        "#,
+    )?;
+
+    let src = context.temp_dir.child("src").child("albatross");
+    src.create_dir_all()?;
+
+    let init = src.child("__init__.py");
+    init.touch()?;
+
+    let child = context.temp_dir.child("child");
+    fs_err::create_dir_all(&child)?;
+
+    let pyproject_toml = child.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+
+        [build-system]
+        requires = ["setuptools>=42"]
+        build-backend = "setuptools.build_meta"
+
+        [tool.uv]
+        dev-dependencies = ["iniconfig>1"]
+        "#,
+    )?;
+
+    let src = child.child("src").child("albatross");
+    src.create_dir_all()?;
+
+    let init = src.child("__init__.py");
+    init.touch()?;
+
+    uv_snapshot!(context.filters(), context.sync().arg("--dev"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    Prepared 5 packages in [TIME]
+    Installed 5 packages in [TIME]
+     + anyio==4.3.0
+     + child==0.1.0 (from file://[TEMP_DIR]/child)
+     + idna==3.6
+     + root==0.1.0 (from file://[TEMP_DIR]/)
+     + sniffio==1.3.1
+    "###);
+
+    Ok(())
+}