Wait for distribution metadata with --no-deps (#1812)

## Summary

We still need to wait for the distribution metadata (for direct
dependencies), even when resolving with `--no-deps`, since we rely on it
to report diagnostics to the user.

Closes #1801.

crates/uv-resolver/src/resolver/mod.rs

@@ -832,6 +832,25 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
             PubGrubPackage::Package(package_name, extra, url) => {
                 // If we're excluding transitive dependencies, short-circuit.
                 if self.dependency_mode.is_direct() {
+                    // If an extra is provided, wait for the metadata to be available, since it's
+                    // still required for reporting diagnostics.
+                    if extra.is_some() {
+                        // Determine the distribution to lookup.
+                        let dist = match url {
+                            Some(url) => PubGrubDistribution::from_url(package_name, url),
+                            None => PubGrubDistribution::from_registry(package_name, version),
+                        };
+                        let package_id = dist.package_id();
+
+                        // Wait for the metadata to be available.
+                        self.index
+                            .distributions
+                            .wait(&package_id)
+                            .instrument(info_span!("distributions_wait", %package_id))
+                            .await
+                            .ok_or(ResolveError::Unregistered)?;
+                    }
+
                     return Ok(Dependencies::Available(DependencyConstraints::default()));
                 }
 

crates/uv/tests/pip_compile.rs

@@ -3859,3 +3859,54 @@ fn unsupported_scheme() -> Result<()> {
 
     Ok(())
 }
+
+/// Resolve a package with `--no-deps`, including a valid extra.
+#[test]
+fn no_deps_valid_extra() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("flask[dotenv]")?;
+
+    uv_snapshot!(context.compile()
+            .arg("requirements.in")
+            .arg("--no-deps"), @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 --no-deps
+    flask==3.0.0
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    "###
+    );
+
+    Ok(())
+}
+
+/// Resolve a package with `--no-deps`, including an invalid extra.
+#[test]
+fn no_deps_invalid_extra() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("flask[empty]")?;
+
+    uv_snapshot!(context.compile()
+            .arg("requirements.in")
+            .arg("--no-deps"), @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 --no-deps
+    flask==3.0.0
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    warning: The package `flask==3.0.0` does not have an extra named `empty`.
+    "###
+    );
+
+    Ok(())
+}