Fix cargo tree -p output with feature-unification=workspace

src/cargo/ops/tree/mod.rs

@@ -182,31 +182,46 @@ pub fn build_and_print(ws: &Workspace<'_>, opts: &TreeOptions) -> CargoResult<()
         .collect();
 
     for SpecsAndResolvedFeatures {
-        specs,
+        specs: entry_specs,
         resolved_features,
     } in ws_resolve.specs_and_features
     {
         let mut graph = graph::build(
             ws,
             &ws_resolve.targeted_resolve,
             &resolved_features,
-            &specs,
+            &entry_specs,
             &opts.cli_features,
             &target_data,
             &requested_kinds,
             package_map.clone(),
             opts,
         )?;
 
-        let root_specs = if opts.invert.is_empty() {
-            specs
+        let root_ids = if opts.invert.is_empty() {
+            let entry_ids = ws_resolve.targeted_resolve.specs_to_ids(&entry_specs)?;
+            let requested_ids = ws_resolve
+                .targeted_resolve
+                .specs_to_ids(&specs)?
+                .into_iter()
+                .collect::<HashSet<_>>();
+
+            // `entry_specs` can be broader than the CLI request (for example,
+            // all workspace members when `feature-unification=workspace`).
+            // Keep only the packages explicitly requested by `-p`.
+            entry_ids
+                .into_iter()
+                .filter(|id| requested_ids.contains(id))
+                .collect()
         } else {
-            opts.invert
+            let invert_specs = opts
+                .invert
                 .iter()
                 .map(|p| PackageIdSpec::parse(p))
-                .collect::<Result<Vec<PackageIdSpec>, _>>()?
+                .collect::<Result<Vec<PackageIdSpec>, _>>()?;
+
+            ws_resolve.targeted_resolve.specs_to_ids(&invert_specs)?
         };
-        let root_ids = ws_resolve.targeted_resolve.specs_to_ids(&root_specs)?;
         let root_indexes = graph.indexes_from_ids(&root_ids);
 
         let root_indexes = if opts.duplicates {

tests/testsuite/feature_unification.rs

@@ -835,6 +835,18 @@ b v0.1.0 ([ROOT]/foo/b)
 └── outside feature "default"
     └── outside v0.1.0
 
+"#]])
+        .run();
+
+    p.cargo("tree -p a")
+        .arg("-Zfeature-unification")
+        .masquerade_as_nightly_cargo(&["feature-unification"])
+        .env("CARGO_RESOLVER_FEATURE_UNIFICATION", "workspace")
+        .with_stdout_data(str![[r#"
+a v0.1.0 ([ROOT]/foo/a)
+├── common v0.1.0 ([ROOT]/foo/common)
+└── outside v0.1.0
+
 "#]])
         .run();
 }