fix(doc): Respect public-dependency when documenting deps

Author: ojuschugh1

src/cargo/core/compiler/unit_dependencies.rs

@@ -67,6 +67,12 @@ struct State<'a, 'gctx> {
     /// dependency from a to b was added purely because it was a dev-dependency.
     /// This is used during `connect_run_custom_build_deps`.
     dev_dependency_edges: HashSet<(Unit, Unit)>,
+
+    /// Package IDs of the root units (i.e. the packages the user asked to
+    /// compile). Used when deciding whether to document a dependency: roots
+    /// always get all their direct deps documented, while non-roots only
+    /// get public deps documented when `-Zpublic-dependency` is active.
+    root_pkg_ids: HashSet<PackageId>,
 }
 
 /// A boolean-like to indicate if a `Unit` is an artifact or not.
@@ -126,6 +132,7 @@ pub fn build_unit_dependencies<'a, 'gctx>(
         interner,
         scrape_units,
         dev_dependency_edges: HashSet::new(),
+        root_pkg_ids: roots.iter().map(|u| u.pkg.package_id()).collect(),
     };
 
     let std_unit_deps = calc_deps_of_std(&mut state, std_roots)?;
@@ -637,6 +644,19 @@ fn compute_deps_doc(
     // built. If we're documenting *all* libraries, then we also depend on
     // the documentation of the library being built.
     let mut ret = Vec::new();
+
+    let public_deps_enabled = state.gctx.cli_unstable().public_dependency
+        || unit
+            .pkg
+            .manifest()
+            .unstable_features()
+            .is_enabled(Feature::public_dependency());
+
+    // Whether this package is a root of the compilation (i.e. selected by
+    // the user). Roots always have all their direct deps documented,
+    // regardless of public/private status.
+    let is_root = state.root_pkg_ids.contains(&unit.pkg.package_id());
+
     for (id, deps) in state.deps(unit, unit_for) {
         let Some(dep_lib) = calc_artifact_deps(unit, unit_for, id, &deps, state, &mut ret)? else {
             continue;
@@ -657,7 +677,17 @@ fn compute_deps_doc(
             IS_NO_ARTIFACT_DEP,
         )?;
         ret.push(lib_unit_dep);
-        if dep_lib.documented() && state.intent.wants_deps_docs() {
+
+        // Decide whether to document this dependency. When
+        // public-dependency is enabled, only document direct deps of root
+        // packages and public deps (recursively).
+        let should_doc_dep = if is_root || !public_deps_enabled {
+            true
+        } else {
+            state.resolve().is_public_dep(unit.pkg.package_id(), id)
+        };
+
+        if dep_lib.documented() && state.intent.wants_deps_docs() && should_doc_dep {
             // Document this lib as well.
             let doc_unit_dep = new_unit_dep(
                 state,

tests/testsuite/doc.rs

@@ -4180,6 +4180,7 @@ fn doc_direct_deps_always_documented() {
 #[cargo_test(nightly, reason = "public-dependency feature is unstable")]
 fn doc_with_transitive_private_dependency() {
     // foo -> bar (direct dep) -> baz (private dep of bar, transitive to foo)
+    // baz should NOT be documented because it is a private transitive dep.
 
     Package::new("baz", "0.0.1")
         .file("src/lib.rs", "pub fn baz() {}")
@@ -4218,7 +4219,6 @@ fn doc_with_transitive_private_dependency() {
 [DOWNLOADING] crates ...
 [DOWNLOADED] baz v0.0.1 (registry `dummy-registry`)
 [DOWNLOADED] bar v0.0.1 (registry `dummy-registry`)
-[DOCUMENTING] baz v0.0.1
 [CHECKING] baz v0.0.1
 [DOCUMENTING] bar v0.0.1
 [CHECKING] bar v0.0.1
@@ -4233,7 +4233,7 @@ fn doc_with_transitive_private_dependency() {
 
     assert!(p.root().join("target/doc/foo/index.html").is_file());
     assert!(p.root().join("target/doc/bar/index.html").is_file());
-    assert!(p.root().join("target/doc/baz/index.html").is_file());
+    assert!(!p.root().join("target/doc/baz/index.html").is_file());
 }
 
 #[cargo_test(nightly, reason = "public-dependency feature is unstable")]
@@ -4290,17 +4290,19 @@ fn doc_mixed_public_private_deps() {
             .join("target/doc/priv_dep_with_dep/index.html")
             .is_file()
     );
-    assert!(p.root().join("target/doc/transitive/index.html").is_file());
+    assert!(!p.root().join("target/doc/transitive/index.html").is_file());
 }
 
 #[cargo_test(nightly, reason = "public-dependency feature is unstable")]
 fn doc_workspace_member_private_dep() {
     // selected and skipped are both workspace members.
     // selected has a private dep on skipped.
     // skipped has a dep on transitive (a registry crate).
-    // Running `cargo doc -p selected` currently documents all of them,
-    // including transitive, because the public-dependency filter treats
-    // workspace members the same as roots.
+    //
+    // Running `cargo doc -p selected`, selected is the root so all its
+    // direct deps (skipped) are documented. But skipped is not a root,
+    // so the public-dependency filter applies: transitive is not marked
+    // public by skipped, so it should not be documented.
 
     Package::new("transitive", "0.0.1")
         .file("src/lib.rs", "pub fn transitive() {}")
@@ -4350,6 +4352,7 @@ fn doc_workspace_member_private_dep() {
 
     assert!(p.root().join("target/doc/selected/index.html").is_file());
     assert!(p.root().join("target/doc/skipped/index.html").is_file());
-    // transitive is documented under the current behavior
-    assert!(p.root().join("target/doc/transitive/index.html").is_file());
+    // transitive is not documented: skipped is not a root, so the
+    // public-dependency filter kicks in and transitive is not public
+    assert!(!p.root().join("target/doc/transitive/index.html").is_file());
 }