Add support for pip-compile's `--unsafe-package` flag (#1889)

## Summary

In uv, we're going to use `--no-emit-package` for this, to convey that
the package will be included in the resolution but not in the output
file. It also mirrors flags like `--emit-index-url`.

We're also including an `--unsafe-package` alias.

Closes https://github.com/astral-sh/uv/issues/1415.

crates/uv-resolver/src/resolution.rs

@@ -257,6 +257,13 @@ impl ResolutionGraph {
         self.petgraph.node_count() == 0
     }
 
+    /// Returns `true` if the graph contains the given package.
+    pub fn contains(&self, name: &PackageName) -> bool {
+        self.petgraph
+            .node_indices()
+            .any(|index| self.petgraph[index].name() == name)
+    }
+
     /// Return the [`Diagnostic`]s that were encountered while building the graph.
     pub fn diagnostics(&self) -> &[Diagnostic] {
         &self.diagnostics
@@ -273,6 +280,8 @@ impl ResolutionGraph {
 pub struct DisplayResolutionGraph<'a> {
     /// The underlying graph.
     resolution: &'a ResolutionGraph,
+    /// The packages to exclude from the output.
+    no_emit_packages: &'a [PackageName],
     /// Whether to include hashes in the output.
     show_hashes: bool,
     /// Whether to include annotations in the output, to indicate which dependency or dependencies
@@ -285,7 +294,7 @@ pub struct DisplayResolutionGraph<'a> {
 
 impl<'a> From<&'a ResolutionGraph> for DisplayResolutionGraph<'a> {
     fn from(resolution: &'a ResolutionGraph) -> Self {
-        Self::new(resolution, false, true, AnnotationStyle::default())
+        Self::new(resolution, &[], false, true, AnnotationStyle::default())
     }
 }
 
@@ -293,12 +302,14 @@ impl<'a> DisplayResolutionGraph<'a> {
     /// Create a new [`DisplayResolutionGraph`] for the given graph.
     pub fn new(
         underlying: &'a ResolutionGraph,
+        no_emit_packages: &'a [PackageName],
         show_hashes: bool,
         include_annotations: bool,
         annotation_style: AnnotationStyle,
     ) -> DisplayResolutionGraph<'a> {
         Self {
             resolution: underlying,
+            no_emit_packages,
             show_hashes,
             include_annotations,
             annotation_style,
@@ -348,15 +359,19 @@ impl std::fmt::Display for DisplayResolutionGraph<'_> {
             .resolution
             .petgraph
             .node_indices()
-            .map(|index| {
+            .filter_map(|index| {
                 let dist = &self.resolution.petgraph[index];
                 let name = dist.name();
+                if self.no_emit_packages.contains(name) {
+                    return None;
+                }
+
                 let node = if let Some((editable, _)) = self.resolution.editables.get(name) {
                     Node::Editable(name, editable)
                 } else {
                     Node::Distribution(name, dist)
                 };
-                (index, node)
+                Some((index, node))
             })
             .collect::<Vec<_>>();
 

crates/uv/src/commands/pip_compile.rs

@@ -52,6 +52,7 @@ pub(crate) async fn pip_compile(
     dependency_mode: DependencyMode,
     upgrade: Upgrade,
     generate_hashes: bool,
+    no_emit_packages: Vec<PackageName>,
     include_annotations: bool,
     include_header: bool,
     include_index_url: bool,
@@ -383,12 +384,30 @@ pub(crate) async fn pip_compile(
         "{}",
         DisplayResolutionGraph::new(
             &resolution,
+            &no_emit_packages,
             generate_hashes,
             include_annotations,
             annotation_style,
         )
     )?;
 
+    // If any "unsafe" packages were excluded, notify the user.
+    let excluded = no_emit_packages
+        .into_iter()
+        .filter(|name| resolution.contains(name))
+        .collect::<Vec<_>>();
+    if !excluded.is_empty() {
+        writeln!(writer)?;
+        writeln!(
+            writer,
+            "{}",
+            "# The following packages were included while generating the resolution:".green()
+        )?;
+        for package in excluded {
+            writeln!(writer, "# {package}")?;
+        }
+    }
+
     Ok(ExitStatus::Success)
 }
 

crates/uv/src/compat/mod.rs

@@ -54,9 +54,6 @@ pub(crate) struct PipCompileCompatArgs {
     #[clap(long, hide = true)]
     no_emit_trusted_host: bool,
 
-    #[clap(long, hide = true)]
-    unsafe_package: Vec<String>,
-
     #[clap(long, hide = true)]
     config: Option<String>,
 
@@ -171,12 +168,6 @@ impl CompatArgs for PipCompileCompatArgs {
             );
         }
 
-        if !self.unsafe_package.is_empty() {
-            return Err(anyhow!(
-                "pip-compile's `--unsafe-package` is not supported."
-            ));
-        }
-
         if self.config.is_some() {
             return Err(anyhow!(
                 "pip-compile's `--config` is unsupported (uv does not use a configuration file)."

crates/uv/src/main.rs

@@ -352,6 +352,11 @@ struct PipCompileArgs {
     #[arg(long, value_parser = date_or_datetime, hide = true)]
     exclude_newer: Option<DateTime<Utc>>,
 
+    /// Specify a package to omit from the output resolution. Its dependencies will still be
+    /// included in the resolution. Equivalent to pip-compile's `--unsafe-package` option.
+    #[clap(long, alias = "unsafe-package")]
+    no_emit_package: Vec<PackageName>,
+
     /// Include `--index-url` and `--extra-index-url` entries in the generated output file.
     #[clap(long, hide = true)]
     emit_index_url: bool,
@@ -904,6 +909,7 @@ async fn run() -> Result<ExitStatus> {
                 dependency_mode,
                 upgrade,
                 args.generate_hashes,
+                args.no_emit_package,
                 !args.no_annotate,
                 !args.no_header,
                 args.emit_index_url,

crates/uv/tests/pip_compile.rs

@@ -4225,3 +4225,46 @@ fn override_with_incompatible_constraint() -> Result<()> {
 
     Ok(())
 }
+
+/// Resolve a package, marking a dependency as unsafe.
+#[test]
+fn unsafe_package() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("flask")?;
+
+    uv_snapshot!(context.compile()
+            .arg("requirements.in")
+            .arg("--unsafe-package")
+            .arg("jinja2")
+            .arg("--unsafe-package")
+            .arg("pydantic"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2023-11-18T12:00:00Z requirements.in --unsafe-package jinja2 --unsafe-package pydantic
+    blinker==1.7.0
+        # via flask
+    click==8.1.7
+        # via flask
+    flask==3.0.0
+    itsdangerous==2.1.2
+        # via flask
+    markupsafe==2.1.3
+        # via
+        #   jinja2
+        #   werkzeug
+    werkzeug==3.0.1
+        # via flask
+
+    # The following packages were included while generating the resolution:
+    # jinja2
+
+    ----- stderr -----
+    Resolved 7 packages in [TIME]
+    "###
+    );
+
+    Ok(())
+}