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

Author: ojuschugh1

src/cargo/core/compiler/unit_dependencies.rs

@@ -637,6 +637,16 @@ 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 is_member = state.ws.is_member(&unit.pkg);
+
+    // Check if public-dependency feature is enabled
+    let public_deps_enabled = state.gctx.cli_unstable().public_dependency
+        || unit
+            .pkg
+            .manifest()
+            .unstable_features()
+            .is_enabled(Feature::public_dependency());
+
     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 +667,20 @@ 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 dependencies of workspace members
+        // - Public dependencies (recursively)
+        // This dramatically speeds up documentation builds by excluding indirect
+        // private dependencies that cannot be used by readers of the docs.
+        let should_doc_dep = if is_member || !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

@@ -4097,7 +4097,6 @@ fn doc_with_public_dependency_transitive() {
         )
         .run();
 
-    // All four are documented: the whole chain is public.
     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());
@@ -4168,7 +4167,7 @@ fn doc_direct_deps_always_documented() {
 #[cargo_test(nightly, reason = "public-dependency feature is unstable")]
 fn doc_with_private_dependency() {
     // foo -> bar (any) -> baz (private)
-    // foo, bar, and baz are all documented
+    // Only foo and bar documented, not baz (transitive private dep)
 
     Package::new("baz", "0.0.1")
         .file("src/lib.rs", "pub fn baz() {}")
@@ -4185,7 +4184,7 @@ fn doc_with_private_dependency() {
             "Cargo.toml",
             r#"
                 cargo-features = ["public-dependency"]
-
+                
                 [package]
                 name = "foo"
                 version = "0.0.1"
@@ -4207,7 +4206,6 @@ fn doc_with_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
@@ -4222,8 +4220,7 @@ fn doc_with_private_dependency() {
 
     assert!(p.root().join("target/doc/foo/index.html").is_file());
     assert!(p.root().join("target/doc/bar/index.html").is_file());
-    // baz is documented because cargo docs all transitive deps
-    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")]
@@ -4252,7 +4249,7 @@ fn doc_mixed_public_private_deps() {
             "Cargo.toml",
             r#"
                 cargo-features = ["public-dependency"]
-
+                
                 [package]
                 name = "foo"
                 version = "0.0.1"
@@ -4281,6 +4278,6 @@ fn doc_mixed_public_private_deps() {
             .is_file()
     );
 
-    // transitive is also documented (all transitive deps are documented)
-    assert!(p.root().join("target/doc/transitive/index.html").is_file());
+    // transitive should NOT be documented
+    assert!(!p.root().join("target/doc/transitive/index.html").is_file());
 }