implement --no-dedupe for uv pip tree (#4449)

<!--
Thank you for contributing to uv! To help us out with reviewing, please
consider the following:

- Does this pull request include a summary of the change? (See below.)
- Does this pull request include a descriptive title?
- Does this pull request include references to any relevant issues?
-->

## Summary
Resolves https://github.com/astral-sh/uv/issues/4439 partially.

Implements for `uv pip tree`:
- `--no-dedupe` flag, similar to `cargo tree --no-dedupe` .
- denote dependency cycles with `(#)` and add a footnote if there's a
cycle (using `(*)` would require keeping track of the cycle state, so
opted to do this instead).
<!-- What's the purpose of the change? What does it do, and why? -->

## Test Plan
The existing tests pass + added a couple of tests to validate
`--no-dedupe` behavior.
<!-- How was it tested? -->

crates/uv-cli/src/lib.rs

@@ -1385,6 +1385,14 @@ pub struct PipShowArgs {
 #[derive(Args)]
 #[allow(clippy::struct_excessive_bools)]
 pub struct PipTreeArgs {
+    /// Do not de-duplicate repeated dependencies.
+    /// Usually, when a package has already displayed its dependencies,
+    /// further occurrences will not re-display its dependencies,
+    /// and will include a (*) to indicate it has already been shown.
+    /// This flag will cause those duplicates to be repeated.
+    #[arg(long)]
+    pub no_dedupe: bool,
+
     /// Validate the virtual environment, to detect packages with missing dependencies or other
     /// issues.
     #[arg(long, overrides_with("no_strict"))]

crates/uv/src/commands/pip/tree.rs

@@ -20,6 +20,7 @@ use pypi_types::VerbatimParsedUrl;
 
 /// Display the installed packages in the current environment as a dependency tree.
 pub(crate) fn pip_tree(
+    no_dedupe: bool,
     strict: bool,
     python: Option<&str>,
     system: bool,
@@ -43,7 +44,7 @@ pub(crate) fn pip_tree(
     // Build the installed index.
     let site_packages = SitePackages::from_executable(&environment)?;
 
-    let rendered_tree = DisplayDependencyGraph::new(&site_packages)
+    let rendered_tree = DisplayDependencyGraph::new(&site_packages, no_dedupe)
         .render()
         .join("\n");
     writeln!(printer.stdout(), "{rendered_tree}").unwrap();
@@ -54,6 +55,9 @@ pub(crate) fn pip_tree(
             "(*) Package tree already displayed".italic()
         )?;
     }
+    if rendered_tree.contains('#') {
+        writeln!(printer.stdout(), "{}", "(#) Dependency cycle".italic())?;
+    }
 
     // Validate that the environment is consistent.
     if strict {
@@ -91,22 +95,6 @@ fn required_with_no_extra(dist: &InstalledDist) -> Vec<pep508_rs::Requirement<Ve
         .collect::<Vec<_>>();
 }
 
-// Render the line for the given installed distribution in the dependency tree.
-fn render_line(installed_dist: &InstalledDist, is_visited: bool) -> String {
-    let mut line = String::new();
-    write!(
-        &mut line,
-        "{} v{}",
-        installed_dist.name(),
-        installed_dist.version()
-    )
-    .unwrap();
-
-    if is_visited {
-        line.push_str(" (*)");
-    }
-    line
-}
 #[derive(Debug)]
 struct DisplayDependencyGraph<'a> {
     site_packages: &'a SitePackages,
@@ -116,11 +104,14 @@ struct DisplayDependencyGraph<'a> {
     // It is used to determine the starting nodes when recursing the
     // dependency graph.
     required_packages: HashSet<PackageName>,
+
+    // Whether to de-duplicate the displayed dependencies.
+    no_dedupe: bool,
 }
 
 impl<'a> DisplayDependencyGraph<'a> {
     /// Create a new [`DisplayDependencyGraph`] for the set of installed distributions.
-    fn new(site_packages: &'a SitePackages) -> DisplayDependencyGraph<'a> {
+    fn new(site_packages: &'a SitePackages, no_dedupe: bool) -> DisplayDependencyGraph<'a> {
         let mut dist_by_package_name = HashMap::new();
         let mut required_packages = HashSet::new();
         for site_package in site_packages.iter() {
@@ -136,6 +127,7 @@ impl<'a> DisplayDependencyGraph<'a> {
             site_packages,
             dist_by_package_name,
             required_packages,
+            no_dedupe,
         }
     }
 
@@ -146,14 +138,22 @@ impl<'a> DisplayDependencyGraph<'a> {
         visited: &mut HashSet<String>,
         path: &mut Vec<String>,
     ) -> Vec<String> {
-        let mut lines = Vec::new();
         let package_name = installed_dist.name().to_string();
         let is_visited = visited.contains(&package_name);
-        lines.push(render_line(installed_dist, is_visited));
-        if is_visited {
-            return lines;
+        let line = format!("{} v{}", package_name, installed_dist.version());
+
+        if path.contains(&package_name) {
+            return vec![format!("{} (#)", line)];
         }
 
+        // If the package has been visited and de-duplication is enabled (default),
+        // skip the traversal.
+        if is_visited && !self.no_dedupe {
+            return vec![format!("{} (*)", line)];
+        }
+
+        let mut lines = vec![line];
+
         path.push(package_name.clone());
         visited.insert(package_name.clone());
         let required_packages = required_with_no_extra(installed_dist);

crates/uv/src/main.rs

@@ -546,6 +546,7 @@ async fn run() -> Result<ExitStatus> {
             let cache = cache.init()?;
 
             commands::pip_tree(
+                args.no_dedupe,
                 args.shared.strict,
                 args.shared.python.as_deref(),
                 args.shared.system,

crates/uv/src/settings.rs

@@ -954,6 +954,7 @@ impl PipShowSettings {
 #[allow(clippy::struct_excessive_bools)]
 #[derive(Debug, Clone)]
 pub(crate) struct PipTreeSettings {
+    pub(crate) no_dedupe: bool,
     // CLI-only settings.
     pub(crate) shared: PipSettings,
 }
@@ -962,6 +963,7 @@ impl PipTreeSettings {
     /// Resolve the [`PipTreeSettings`] from the CLI and workspace configuration.
     pub(crate) fn resolve(args: PipTreeArgs, filesystem: Option<FilesystemOptions>) -> Self {
         let PipTreeArgs {
+            no_dedupe,
             strict,
             no_strict,
             python,
@@ -970,6 +972,7 @@ impl PipTreeSettings {
         } = args;
 
         Self {
+            no_dedupe,
             // Shared settings.
             shared: PipSettings::combine(
                 PipOptions {

crates/uv/tests/pip_tree.rs

@@ -328,8 +328,8 @@ fn cyclic_dependency() {
     uv-cyclic-dependencies-c v0.1.0
     └── uv-cyclic-dependencies-a v0.1.0
         └── uv-cyclic-dependencies-b v0.1.0
-            └── uv-cyclic-dependencies-a v0.1.0 (*)
-    (*) Package tree already displayed
+            └── uv-cyclic-dependencies-a v0.1.0 (#)
+    (#) Dependency cycle
 
     ----- stderr -----
     "###
@@ -541,6 +541,202 @@ fn multiple_packages_shared_descendant() {
     );
 }
 
+// Ensure that --no-dedupe behaves as expected
+// in the presence of dependency cycles.
+#[test]
+#[cfg(not(windows))]
+fn no_dedupe_and_cycle() {
+    let context = TestContext::new("3.12");
+
+    let requirements_txt = context.temp_dir.child("requirements.txt");
+    requirements_txt
+        .write_str(
+            r"
+        pendulum==3.0.0
+        boto3==1.34.69
+    ",
+        )
+        .unwrap();
+
+    uv_snapshot!(install_command(&context)
+        .arg("-r")
+        .arg("requirements.txt")
+        .arg("--strict"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 10 packages in [TIME]
+    Prepared 10 packages in [TIME]
+    Installed 10 packages in [TIME]
+     + boto3==1.34.69
+     + botocore==1.34.69
+     + jmespath==1.0.1
+     + pendulum==3.0.0
+     + python-dateutil==2.9.0.post0
+     + s3transfer==0.10.1
+     + six==1.16.0
+     + time-machine==2.14.1
+     + tzdata==2024.1
+     + urllib3==2.2.1
+
+    "###
+    );
+
+    let mut command = Command::new(get_bin());
+    command
+        .arg("pip")
+        .arg("install")
+        .arg("uv-cyclic-dependencies-c==0.1.0")
+        .arg("--cache-dir")
+        .arg(context.cache_dir.path())
+        .arg("--index-url")
+        .arg("https://test.pypi.org/simple/")
+        .env("VIRTUAL_ENV", context.venv.as_os_str())
+        .env("UV_NO_WRAP", "1")
+        .current_dir(&context.temp_dir);
+    if cfg!(all(windows, debug_assertions)) {
+        // TODO(konstin): Reduce stack usage in debug mode enough that the tests pass with the
+        // default windows stack of 1MB
+        command.env("UV_STACK_SIZE", (2 * 1024 * 1024).to_string());
+    }
+
+    uv_snapshot!(context.filters(), command, @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 3 packages in [TIME]
+    Prepared 3 packages in [TIME]
+    Installed 3 packages in [TIME]
+     + uv-cyclic-dependencies-a==0.1.0
+     + uv-cyclic-dependencies-b==0.1.0
+     + uv-cyclic-dependencies-c==0.1.0
+    "###
+    );
+
+    uv_snapshot!(context.filters(), Command::new(get_bin())
+        .arg("pip")
+        .arg("tree")
+        .arg("--cache-dir")
+        .arg(context.cache_dir.path())
+        .arg("--no-dedupe")
+        .env("VIRTUAL_ENV", context.venv.as_os_str())
+        .env("UV_NO_WRAP", "1")
+        .current_dir(&context.temp_dir), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    boto3 v1.34.69
+    ├── botocore v1.34.69
+    │   ├── jmespath v1.0.1
+    │   └── python-dateutil v2.9.0.post0
+    │       └── six v1.16.0
+    ├── jmespath v1.0.1
+    └── s3transfer v0.10.1
+        └── botocore v1.34.69
+            ├── jmespath v1.0.1
+            └── python-dateutil v2.9.0.post0
+                └── six v1.16.0
+    pendulum v3.0.0
+    ├── python-dateutil v2.9.0.post0
+    │   └── six v1.16.0
+    └── tzdata v2024.1
+    time-machine v2.14.1
+    └── python-dateutil v2.9.0.post0
+        └── six v1.16.0
+    urllib3 v2.2.1
+    uv-cyclic-dependencies-c v0.1.0
+    └── uv-cyclic-dependencies-a v0.1.0
+        └── uv-cyclic-dependencies-b v0.1.0
+            └── uv-cyclic-dependencies-a v0.1.0 (#)
+    (#) Dependency cycle
+
+    ----- stderr -----
+    "###
+    );
+}
+
+#[test]
+#[cfg(not(windows))]
+fn no_dedupe() {
+    let context = TestContext::new("3.12");
+
+    let requirements_txt = context.temp_dir.child("requirements.txt");
+    requirements_txt
+        .write_str(
+            r"
+        pendulum==3.0.0
+        boto3==1.34.69
+    ",
+        )
+        .unwrap();
+
+    uv_snapshot!(install_command(&context)
+        .arg("-r")
+        .arg("requirements.txt")
+        .arg("--strict"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 10 packages in [TIME]
+    Prepared 10 packages in [TIME]
+    Installed 10 packages in [TIME]
+     + boto3==1.34.69
+     + botocore==1.34.69
+     + jmespath==1.0.1
+     + pendulum==3.0.0
+     + python-dateutil==2.9.0.post0
+     + s3transfer==0.10.1
+     + six==1.16.0
+     + time-machine==2.14.1
+     + tzdata==2024.1
+     + urllib3==2.2.1
+
+    "###
+    );
+
+    uv_snapshot!(context.filters(), Command::new(get_bin())
+        .arg("pip")
+        .arg("tree")
+        .arg("--cache-dir")
+        .arg(context.cache_dir.path())
+        .arg("--no-dedupe")
+        .env("VIRTUAL_ENV", context.venv.as_os_str())
+        .env("UV_NO_WRAP", "1")
+        .current_dir(&context.temp_dir), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    boto3 v1.34.69
+    ├── botocore v1.34.69
+    │   ├── jmespath v1.0.1
+    │   └── python-dateutil v2.9.0.post0
+    │       └── six v1.16.0
+    ├── jmespath v1.0.1
+    └── s3transfer v0.10.1
+        └── botocore v1.34.69
+            ├── jmespath v1.0.1
+            └── python-dateutil v2.9.0.post0
+                └── six v1.16.0
+    pendulum v3.0.0
+    ├── python-dateutil v2.9.0.post0
+    │   └── six v1.16.0
+    └── tzdata v2024.1
+    time-machine v2.14.1
+    └── python-dateutil v2.9.0.post0
+        └── six v1.16.0
+    urllib3 v2.2.1
+
+    ----- stderr -----
+    "###
+    );
+}
+
 #[test]
 fn with_editable() {
     let context = TestContext::new("3.12");