Implement pip freeze --path (#10488)

## Summary

Resolves #5952

Add a `--path` option to `uv pip freeze` to be compatible with `pip
freeze`

## Test Plan

New snapshot tests

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/uv-cli/src/lib.rs

@@ -1904,6 +1904,10 @@ pub struct PipFreezeArgs {
     )]
     pub python: Option<Maybe<String>>,
 
+    /// Restrict to the specified installation path for listing packages (can be used multiple times).
+    #[arg(long("path"), value_parser = parse_file_path)]
+    pub paths: Option<Vec<PathBuf>>,
+
     /// List packages in the system Python environment.
     ///
     /// Disables discovery of virtual environments.

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

@@ -1,4 +1,5 @@
 use std::fmt::Write;
+use std::path::PathBuf;
 
 use anyhow::Result;
 use itertools::Itertools;
@@ -19,6 +20,7 @@ pub(crate) fn pip_freeze(
     strict: bool,
     python: Option<&str>,
     system: bool,
+    paths: Option<Vec<PathBuf>>,
     cache: &Cache,
     printer: Printer,
 ) -> Result<ExitStatus> {
@@ -31,49 +33,68 @@ pub(crate) fn pip_freeze(
 
     report_target_environment(&environment, cache, printer)?;
 
-    // Build the installed index.
-    let site_packages = SitePackages::from_environment(&environment)?;
-    for dist in site_packages
+    // Collect all the `site-packages` directories.
+    let site_packages = match paths {
+        Some(paths) => {
+            paths
+                .into_iter()
+                .filter_map(|path| {
+                    environment
+                        .clone()
+                        .with_target(uv_python::Target::from(path))
+                        // Drop invalid paths as per `pip freeze`.
+                        .ok()
+                })
+                .map(|environment| SitePackages::from_environment(&environment))
+                .collect::<Result<Vec<_>>>()?
+        }
+        None => vec![SitePackages::from_environment(&environment)?],
+    };
+
+    site_packages
         .iter()
+        .flat_map(uv_installer::SitePackages::iter)
         .filter(|dist| !(exclude_editable && dist.is_editable()))
         .sorted_unstable_by(|a, b| a.name().cmp(b.name()).then(a.version().cmp(b.version())))
-    {
-        match dist {
+        .map(|dist| match dist {
             InstalledDist::Registry(dist) => {
-                writeln!(printer.stdout(), "{}=={}", dist.name().bold(), dist.version)?;
+                format!("{}=={}", dist.name().bold(), dist.version)
             }
             InstalledDist::Url(dist) => {
                 if dist.editable {
-                    writeln!(printer.stdout(), "-e {}", dist.url)?;
+                    format!("-e {}", dist.url)
                 } else {
-                    writeln!(printer.stdout(), "{} @ {}", dist.name().bold(), dist.url)?;
+                    format!("{} @ {}", dist.name().bold(), dist.url)
                 }
             }
             InstalledDist::EggInfoFile(dist) => {
-                writeln!(printer.stdout(), "{}=={}", dist.name().bold(), dist.version)?;
+                format!("{}=={}", dist.name().bold(), dist.version)
             }
             InstalledDist::EggInfoDirectory(dist) => {
-                writeln!(printer.stdout(), "{}=={}", dist.name().bold(), dist.version)?;
+                format!("{}=={}", dist.name().bold(), dist.version)
             }
             InstalledDist::LegacyEditable(dist) => {
-                writeln!(printer.stdout(), "-e {}", dist.target.display())?;
+                format!("-e {}", dist.target.display())
             }
-        }
-    }
+        })
+        .dedup()
+        .try_for_each(|dist| writeln!(printer.stdout(), "{dist}"))?;
 
     // Validate that the environment is consistent.
     if strict {
         // Determine the markers to use for resolution.
         let markers = environment.interpreter().resolver_marker_environment();
 
-        for diagnostic in site_packages.diagnostics(&markers)? {
-            writeln!(
-                printer.stderr(),
-                "{}{} {}",
-                "warning".yellow().bold(),
-                ":".bold(),
-                diagnostic.message().bold()
-            )?;
+        for entry in site_packages {
+            for diagnostic in entry.diagnostics(&markers)? {
+                writeln!(
+                    printer.stderr(),
+                    "{}{} {}",
+                    "warning".yellow().bold(),
+                    ":".bold(),
+                    diagnostic.message().bold()
+                )?;
+            }
         }
     }
 

crates/uv/src/lib.rs

@@ -627,6 +627,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 args.settings.strict,
                 args.settings.python.as_deref(),
                 args.settings.system,
+                args.paths,
                 &cache,
                 printer,
             )

crates/uv/src/settings.rs

@@ -1883,6 +1883,7 @@ impl PipUninstallSettings {
 #[derive(Debug, Clone)]
 pub(crate) struct PipFreezeSettings {
     pub(crate) exclude_editable: bool,
+    pub(crate) paths: Option<Vec<PathBuf>>,
     pub(crate) settings: PipSettings,
 }
 
@@ -1894,13 +1895,15 @@ impl PipFreezeSettings {
             strict,
             no_strict,
             python,
+            paths,
             system,
             no_system,
             compat_args: _,
         } = args;
 
         Self {
             exclude_editable,
+            paths,
             settings: PipSettings::combine(
                 PipOptions {
                     python: python.and_then(Maybe::into_option),

crates/uv/tests/it/pip_freeze.rs

@@ -354,3 +354,102 @@ Version: 0.22.0
 
     Ok(())
 }
+
+#[test]
+fn freeze_path() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let requirements_txt = context.temp_dir.child("requirements.txt");
+    requirements_txt.write_str("MarkupSafe==2.1.3\ntomli==2.0.1")?;
+
+    let target = context.temp_dir.child("install-path");
+
+    // Run `pip sync`.
+    context
+        .pip_sync()
+        .arg(requirements_txt.path())
+        .arg("--target")
+        .arg(target.path())
+        .assert()
+        .success();
+
+    // Run `pip freeze`.
+    uv_snapshot!(context.filters(), context.pip_freeze()
+        .arg("--path")
+        .arg(target.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    markupsafe==2.1.3
+    tomli==2.0.1
+
+    ----- stderr -----
+    ");
+
+    Ok(())
+}
+
+#[test]
+fn freeze_multiple_paths() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let requirements_txt1 = context.temp_dir.child("requirements1.txt");
+    requirements_txt1.write_str("MarkupSafe==2.1.3\ntomli==2.0.1")?;
+
+    let requirements_txt2 = context.temp_dir.child("requirements2.txt");
+    requirements_txt2.write_str("MarkupSafe==2.1.3\nrequests==2.31.0")?;
+
+    let target1 = context.temp_dir.child("install-path1");
+    let target2 = context.temp_dir.child("install-path2");
+
+    // Run `pip sync`.
+    for (target, requirements_txt) in [
+        (target1.path(), requirements_txt1),
+        (target2.path(), requirements_txt2),
+    ] {
+        context
+            .pip_sync()
+            .arg(requirements_txt.path())
+            .arg("--target")
+            .arg(target)
+            .assert()
+            .success();
+    }
+
+    // Run `pip freeze`.
+    uv_snapshot!(context.filters(), context.pip_freeze().arg("--path").arg(target1.path()).arg("--path").arg(target2.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    markupsafe==2.1.3
+    requests==2.31.0
+    tomli==2.0.1
+
+    ----- stderr -----
+    ");
+
+    Ok(())
+}
+
+// We follow pip in just ignoring nonexistent paths
+#[test]
+fn freeze_nonexistent_path() {
+    let context = TestContext::new("3.12");
+
+    let nonexistent_dir = {
+        let dir = context.temp_dir.child("blahblah");
+        assert!(!dir.exists());
+        dir
+    };
+
+    // Run `pip freeze`.
+    uv_snapshot!(context.filters(), context.pip_freeze()
+        .arg("--path")
+        .arg(nonexistent_dir.path()), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    ");
+}

docs/reference/cli.md

@@ -7045,6 +7045,8 @@ uv pip freeze [OPTIONS]
 <p>When disabled, uv will only use locally cached data and locally available files.</p>
 
 <p>May also be set with the <code>UV_OFFLINE</code> environment variable.</p>
+</dd><dt><code>--path</code> <i>paths</i></dt><dd><p>Restrict to the specified installation path for listing packages (can be used multiple times)</p>
+
 </dd><dt><code>--project</code> <i>project</i></dt><dd><p>Run the command within the given project directory.</p>
 
 <p>All <code>pyproject.toml</code>, <code>uv.toml</code>, and <code>.python-version</code> files will be discovered by walking up the directory tree from the project root, as will the project&#8217;s virtual environment (<code>.venv</code>).</p>