Make direct dependency detection respect markers (#2207)

## Summary

When determining "direct" dependencies, we need to ensure that we
respect markers. In the linked issue, the user had an optional
dependency like:

```toml
[project.optional-dependencies]
dev = [
  "setuptools>=64",
  "setuptools_scm>=8"
]
```

By not respecting markers, we tried to resolve `setuptools` to the
lowest-available version. However, since `setuptools>=64` _isn't_
enabled (since it's optional), we won't respect _that_ constraint.

To be consistent, we need to omit optional dependencies just as we will
at resolution time.

Closes #2203.

## Test Plan

`cargo test`

crates/uv-resolver/src/candidate_selector.rs

@@ -4,7 +4,7 @@ use rustc_hash::FxHashMap;
 use distribution_types::CompatibleDist;
 use distribution_types::{DistributionMetadata, IncompatibleWheel, Name, PrioritizedDist};
 use pep440_rs::Version;
-use pep508_rs::{Requirement, VersionOrUrl};
+use pep508_rs::{MarkerEnvironment, Requirement, VersionOrUrl};
 use uv_normalize::PackageName;
 
 use crate::prerelease_mode::PreReleaseStrategy;
@@ -21,11 +21,23 @@ pub(crate) struct CandidateSelector {
 
 impl CandidateSelector {
     /// Return a [`CandidateSelector`] for the given [`Manifest`].
-    pub(crate) fn for_resolution(manifest: &Manifest, options: Options) -> Self {
+    pub(crate) fn for_resolution(
+        options: Options,
+        manifest: &Manifest,
+        markers: &MarkerEnvironment,
+    ) -> Self {
         Self {
-            resolution_strategy: ResolutionStrategy::from_mode(options.resolution_mode, manifest),
-            prerelease_strategy: PreReleaseStrategy::from_mode(options.prerelease_mode, manifest),
-            preferences: Preferences::from(manifest.preferences.as_slice()),
+            resolution_strategy: ResolutionStrategy::from_mode(
+                options.resolution_mode,
+                manifest,
+                markers,
+            ),
+            prerelease_strategy: PreReleaseStrategy::from_mode(
+                options.prerelease_mode,
+                manifest,
+                markers,
+            ),
+            preferences: Preferences::from_requirements(manifest.preferences.as_slice(), markers),
         }
     }
 
@@ -47,17 +59,15 @@ impl CandidateSelector {
 struct Preferences(FxHashMap<PackageName, Version>);
 
 impl Preferences {
-    fn get(&self, package_name: &PackageName) -> Option<&Version> {
-        self.0.get(package_name)
-    }
-}
-
-impl From<&[Requirement]> for Preferences {
-    fn from(requirements: &[Requirement]) -> Self {
+    /// Create a set of [`Preferences`] from a set of requirements.
+    fn from_requirements(requirements: &[Requirement], markers: &MarkerEnvironment) -> Self {
         Self(
             requirements
                 .iter()
                 .filter_map(|requirement| {
+                    if !requirement.evaluate_markers(markers, &[]) {
+                        return None;
+                    }
                     let Some(VersionOrUrl::VersionSpecifier(version_specifiers)) =
                         requirement.version_or_url.as_ref()
                     else {
@@ -74,6 +84,11 @@ impl From<&[Requirement]> for Preferences {
                 .collect(),
         )
     }
+
+    /// Return the pinned version for a package, if any.
+    fn get(&self, package_name: &PackageName) -> Option<&Version> {
+        self.0.get(package_name)
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]

crates/uv-resolver/src/prerelease_mode.rs

@@ -1,6 +1,6 @@
 use rustc_hash::FxHashSet;
 
-use pep508_rs::VersionOrUrl;
+use pep508_rs::{MarkerEnvironment, VersionOrUrl};
 use uv_normalize::PackageName;
 
 use crate::Manifest;
@@ -50,7 +50,11 @@ pub(crate) enum PreReleaseStrategy {
 }
 
 impl PreReleaseStrategy {
-    pub(crate) fn from_mode(mode: PreReleaseMode, manifest: &Manifest) -> Self {
+    pub(crate) fn from_mode(
+        mode: PreReleaseMode,
+        manifest: &Manifest,
+        markers: &MarkerEnvironment,
+    ) -> Self {
         match mode {
             PreReleaseMode::Disallow => Self::Disallow,
             PreReleaseMode::Allow => Self::Allow,
@@ -61,12 +65,12 @@ impl PreReleaseStrategy {
                     .iter()
                     .chain(manifest.constraints.iter())
                     .chain(manifest.overrides.iter())
-                    .chain(
-                        manifest
-                            .editables
-                            .iter()
-                            .flat_map(|(_editable, metadata)| metadata.requires_dist.iter()),
-                    )
+                    .filter(|requirement| requirement.evaluate_markers(markers, &[]))
+                    .chain(manifest.editables.iter().flat_map(|(editable, metadata)| {
+                        metadata.requires_dist.iter().filter(|requirement| {
+                            requirement.evaluate_markers(markers, &editable.extras)
+                        })
+                    }))
                     .filter(|requirement| {
                         let Some(version_or_url) = &requirement.version_or_url else {
                             return false;
@@ -90,12 +94,12 @@ impl PreReleaseStrategy {
                     .iter()
                     .chain(manifest.constraints.iter())
                     .chain(manifest.overrides.iter())
-                    .chain(
-                        manifest
-                            .editables
-                            .iter()
-                            .flat_map(|(_editable, metadata)| metadata.requires_dist.iter()),
-                    )
+                    .filter(|requirement| requirement.evaluate_markers(markers, &[]))
+                    .chain(manifest.editables.iter().flat_map(|(editable, metadata)| {
+                        metadata.requires_dist.iter().filter(|requirement| {
+                            requirement.evaluate_markers(markers, &editable.extras)
+                        })
+                    }))
                     .filter(|requirement| {
                         let Some(version_or_url) = &requirement.version_or_url else {
                             return false;

crates/uv-resolver/src/resolution_mode.rs

@@ -1,5 +1,6 @@
 use rustc_hash::FxHashSet;
 
+use pep508_rs::MarkerEnvironment;
 use uv_normalize::PackageName;
 
 use crate::Manifest;
@@ -31,7 +32,11 @@ pub(crate) enum ResolutionStrategy {
 }
 
 impl ResolutionStrategy {
-    pub(crate) fn from_mode(mode: ResolutionMode, manifest: &Manifest) -> Self {
+    pub(crate) fn from_mode(
+        mode: ResolutionMode,
+        manifest: &Manifest,
+        markers: &MarkerEnvironment,
+    ) -> Self {
         match mode {
             ResolutionMode::Highest => Self::Highest,
             ResolutionMode::Lowest => Self::Lowest,
@@ -40,12 +45,12 @@ impl ResolutionStrategy {
                 manifest
                     .requirements
                     .iter()
-                    .chain(
-                        manifest
-                            .editables
-                            .iter()
-                            .flat_map(|(_editable, metadata)| metadata.requires_dist.iter()),
-                    )
+                    .filter(|requirement| requirement.evaluate_markers(markers, &[]))
+                    .chain(manifest.editables.iter().flat_map(|(editable, metadata)| {
+                        metadata.requires_dist.iter().filter(|requirement| {
+                            requirement.evaluate_markers(markers, &editable.extras)
+                        })
+                    }))
                     .map(|requirement| requirement.name.clone())
                     .collect(),
             ),

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

@@ -158,21 +158,12 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
         index: &'a InMemoryIndex,
         provider: Provider,
     ) -> Result<Self, ResolveError> {
-        let selector = CandidateSelector::for_resolution(&manifest, options);
-
-        // Determine the allowed yanked package versions
-        let allowed_yanks = manifest
-            .requirements
-            .iter()
-            .chain(manifest.constraints.iter())
-            .collect();
-
         Ok(Self {
             index,
             unavailable_packages: DashMap::default(),
             visited: DashSet::default(),
-            selector,
-            allowed_yanks,
+            selector: CandidateSelector::for_resolution(options, &manifest, markers),
+            allowed_yanks: AllowedYanks::from_manifest(&manifest, markers),
             dependency_mode: options.dependency_mode,
             urls: Urls::from_manifest(&manifest, markers)?,
             project: manifest.project,

crates/uv-resolver/src/yanks.rs

@@ -1,28 +1,33 @@
 use rustc_hash::{FxHashMap, FxHashSet};
 
 use pep440_rs::Version;
-use pep508_rs::Requirement;
+use pep508_rs::MarkerEnvironment;
 use uv_normalize::PackageName;
 
+use crate::Manifest;
+
 /// A set of package versions that are permitted, even if they're marked as yanked by the
 /// relevant index.
 #[derive(Debug, Default)]
 pub(crate) struct AllowedYanks(FxHashMap<PackageName, FxHashSet<Version>>);
 
 impl AllowedYanks {
-    /// Returns `true` if the given package version is allowed, even if it's marked as yanked by
-    /// the relevant index.
-    pub(crate) fn allowed(&self, package_name: &PackageName, version: &Version) -> bool {
-        self.0
-            .get(package_name)
-            .is_some_and(|allowed_yanks| allowed_yanks.contains(version))
-    }
-}
-
-impl<'a> FromIterator<&'a Requirement> for AllowedYanks {
-    fn from_iter<T: IntoIterator<Item = &'a Requirement>>(iter: T) -> Self {
+    pub(crate) fn from_manifest(manifest: &Manifest, markers: &MarkerEnvironment) -> Self {
         let mut allowed_yanks = FxHashMap::<PackageName, FxHashSet<Version>>::default();
-        for requirement in iter {
+        for requirement in manifest
+            .requirements
+            .iter()
+            .chain(manifest.constraints.iter())
+            .chain(manifest.overrides.iter())
+            .chain(manifest.preferences.iter())
+            .filter(|requirement| requirement.evaluate_markers(markers, &[]))
+            .chain(manifest.editables.iter().flat_map(|(editable, metadata)| {
+                metadata
+                    .requires_dist
+                    .iter()
+                    .filter(|requirement| requirement.evaluate_markers(markers, &editable.extras))
+            }))
+        {
             let Some(pep508_rs::VersionOrUrl::VersionSpecifier(specifiers)) =
                 &requirement.version_or_url
             else {
@@ -43,4 +48,12 @@ impl<'a> FromIterator<&'a Requirement> for AllowedYanks {
         }
         Self(allowed_yanks)
     }
+
+    /// Returns `true` if the given package version is allowed, even if it's marked as yanked by
+    /// the relevant index.
+    pub(crate) fn allowed(&self, package_name: &PackageName, version: &Version) -> bool {
+        self.0
+            .get(package_name)
+            .is_some_and(|allowed_yanks| allowed_yanks.contains(version))
+    }
 }

crates/uv/tests/pip_compile.rs

@@ -4804,3 +4804,53 @@ dev = [
 
     Ok(())
 }
+
+/// Under `--resolution=lowest-direct`, ignore optional dependencies.
+///
+/// In the below example, ensure that `setuptools` does not resolve to the lowest-available version.
+#[test]
+fn editable_optional_lowest_direct() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    // Create an editable package with an optional URL dependency.
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"[project]
+name = "example"
+version = "0.0.0"
+dependencies = ["setuptools-scm>=8.0.0"]
+requires-python = '>=3.8'
+
+[project.optional-dependencies]
+dev = ["setuptools"]
+"#,
+    )?;
+
+    // Write to a requirements file.
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("-e .")?;
+
+    uv_snapshot!(context.compile()
+        .arg("requirements.in")
+        .arg("--resolution=lowest-direct"), @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 --resolution=lowest-direct
+    -e .
+    packaging==23.2
+        # via setuptools-scm
+    setuptools==68.2.2
+        # via setuptools-scm
+    setuptools-scm==8.0.1
+        # via example
+
+    ----- stderr -----
+    Built 1 editable in [TIME]
+    Resolved 4 packages in [TIME]
+    "###
+    );
+
+    Ok(())
+}