Visit proxy packages eagerly (#10441)

## Summary

The issue here is that we add `urllib3{python_full_version >= '3.8'}` as
a dependency, then `requests{python_full_version >= '3.8'}`, which adds
`urllib3`, but at that point, we haven't expanded
`urllib3{python_full_version >= '3.8'}`, so we "lose" the singleton
constraint. The solution is to ensure that we visit proxies eagerly, so
that we accumulate constraints as early as possible.

Closes
#10425 (comment).

crates/uv-resolver/src/pubgrub/priority.rs

@@ -1,12 +1,13 @@
-use pubgrub::Range;
-use rustc_hash::FxHashMap;
 use std::cmp::Reverse;
 use std::collections::hash_map::OccupiedEntry;
 
-use crate::fork_urls::ForkUrls;
+use pubgrub::Range;
+use rustc_hash::FxHashMap;
+
 use uv_normalize::PackageName;
 use uv_pep440::Version;
 
+use crate::fork_urls::ForkUrls;
 use crate::pubgrub::package::PubGrubPackage;
 use crate::pubgrub::PubGrubPackageInner;
 
@@ -57,6 +58,7 @@ impl PubGrubPriorities {
                 let priority = if urls.get(name).is_some() {
                     PubGrubPriority::DirectUrl(Reverse(index))
                 } else if version.as_singleton().is_some() {
+                    // TODO(charlie): Take local version ranges into account (e.g., `[2.0, 2.0+[max])`).
                     PubGrubPriority::Singleton(Reverse(index))
                 } else {
                     // Keep the conflict-causing packages to avoid loops where we seesaw between
@@ -80,6 +82,7 @@ impl PubGrubPriorities {
                 let priority = if urls.get(name).is_some() {
                     PubGrubPriority::DirectUrl(Reverse(next))
                 } else if version.as_singleton().is_some() {
+                    // TODO(charlie): Take local version ranges into account (e.g., `[2.0, 2.0+[max])`).
                     PubGrubPriority::Singleton(Reverse(next))
                 } else {
                     PubGrubPriority::Unspecified(Reverse(next))
@@ -98,7 +101,7 @@ impl PubGrubPriorities {
             | PubGrubPriority::ConflictEarly(Reverse(index))
             | PubGrubPriority::Singleton(Reverse(index))
             | PubGrubPriority::DirectUrl(Reverse(index)) => Some(*index),
-            PubGrubPriority::Root => None,
+            PubGrubPriority::Proxy | PubGrubPriority::Root => None,
         }
     }
 
@@ -107,9 +110,9 @@ impl PubGrubPriorities {
         let package_priority = match &**package {
             PubGrubPackageInner::Root(_) => Some(PubGrubPriority::Root),
             PubGrubPackageInner::Python(_) => Some(PubGrubPriority::Root),
-            PubGrubPackageInner::Marker { name, .. } => self.package_priority.get(name).copied(),
-            PubGrubPackageInner::Extra { name, .. } => self.package_priority.get(name).copied(),
-            PubGrubPackageInner::Dev { name, .. } => self.package_priority.get(name).copied(),
+            PubGrubPackageInner::Marker { .. } => Some(PubGrubPriority::Proxy),
+            PubGrubPackageInner::Extra { .. } => Some(PubGrubPriority::Proxy),
+            PubGrubPackageInner::Dev { .. } => Some(PubGrubPriority::Proxy),
             PubGrubPackageInner::Package { name, .. } => self.package_priority.get(name).copied(),
         };
         let virtual_package_tiebreaker = self
@@ -224,6 +227,13 @@ pub(crate) enum PubGrubPriority {
     /// [`ForkUrls`].
     DirectUrl(Reverse<usize>),
 
+    /// The package is a proxy package.
+    ///
+    /// We process proxy packages eagerly since each proxy package expands into two "regular"
+    /// [`PubGrubPackage`] packages, which gives us additional constraints while not affecting the
+    /// priorities (since the expanded dependencies are all linked to the same package name).
+    Proxy,
+
     /// The package is the root package.
     Root,
 }

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

@@ -2591,7 +2591,9 @@ impl ForkState {
                 }
             }
 
-            if let Some(name) = self.pubgrub.package_store[for_package]
+            let for_package = &self.pubgrub.package_store[for_package];
+
+            if let Some(name) = for_package
                 .name_no_root()
                 .filter(|name| !workspace_members.contains(name))
             {
@@ -2622,7 +2624,9 @@ impl ForkState {
             }
 
             // Update the package priorities.
-            self.priorities.insert(package, version, &self.fork_urls);
+            if !for_package.is_proxy() {
+                self.priorities.insert(package, version, &self.fork_urls);
+            }
         }
 
         let conflict = self.pubgrub.add_package_version_dependencies(

crates/uv-resolver/src/version_map.rs

@@ -162,6 +162,8 @@ impl VersionMap {
         range: &Ranges<Version>,
     ) -> impl DoubleEndedIterator<Item = (&Version, VersionMapDistHandle)> {
         // Performance optimization: If we only have a single version, return that version directly.
+        //
+        // TODO(charlie): Now that we use local version sentinels, does this ever trigger?
         if let Some(version) = range.as_singleton() {
             either::Either::Left(match self.inner {
                 VersionMapInner::Eager(ref eager) => {

crates/uv/tests/it/lock_conflict.rs

@@ -50,7 +50,7 @@ fn extra_basic() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project[extra2] depends on sortedcontainers==2.4.0 and project[extra1] depends on sortedcontainers==2.3.0, we can conclude that project[extra1] and project[extra2] are incompatible.
+      ╰─▶ Because project[extra1] depends on sortedcontainers==2.3.0 and project[extra2] depends on sortedcontainers==2.4.0, we can conclude that project[extra1] and project[extra2] are incompatible.
           And because your project requires project[extra1] and project[extra2], we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -250,7 +250,7 @@ fn extra_basic_three_extras() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project[project3] depends on sortedcontainers==2.4.0 and project[extra2] depends on sortedcontainers==2.3.0, we can conclude that project[extra2] and project[project3] are incompatible.
+      ╰─▶ Because project[extra2] depends on sortedcontainers==2.3.0 and project[project3] depends on sortedcontainers==2.4.0, we can conclude that project[extra2] and project[project3] are incompatible.
           And because your project requires project[extra2] and project[project3], we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -538,7 +538,7 @@ fn extra_multiple_not_conflicting2() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project[project4] depends on sortedcontainers==2.4.0 and project[project3] depends on sortedcontainers==2.3.0, we can conclude that project[project3] and project[project4] are incompatible.
+      ╰─▶ Because project[project3] depends on sortedcontainers==2.3.0 and project[project4] depends on sortedcontainers==2.4.0, we can conclude that project[project3] and project[project4] are incompatible.
           And because your project requires project[project3] and project[project4], we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -582,7 +582,7 @@ fn extra_multiple_not_conflicting2() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project[project3] depends on sortedcontainers==2.3.0 and project[extra2] depends on sortedcontainers==2.4.0, we can conclude that project[extra2] and project[project3] are incompatible.
+      ╰─▶ Because project[extra2] depends on sortedcontainers==2.4.0 and project[project3] depends on sortedcontainers==2.3.0, we can conclude that project[extra2] and project[project3] are incompatible.
           And because your project requires project[extra2] and project[project3], we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -715,7 +715,7 @@ fn extra_multiple_independent() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project[project4] depends on anyio==4.2.0 and project[project3] depends on anyio==4.1.0, we can conclude that project[project3] and project[project4] are incompatible.
+      ╰─▶ Because project[project3] depends on anyio==4.1.0 and project[project4] depends on anyio==4.2.0, we can conclude that project[project3] and project[project4] are incompatible.
           And because your project requires project[project3] and project[project4], we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -755,7 +755,7 @@ fn extra_multiple_independent() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project[extra2] depends on sortedcontainers==2.4.0 and project[extra1] depends on sortedcontainers==2.3.0, we can conclude that project[extra1] and project[extra2] are incompatible.
+      ╰─▶ Because project[extra1] depends on sortedcontainers==2.3.0 and project[extra2] depends on sortedcontainers==2.4.0, we can conclude that project[extra1] and project[extra2] are incompatible.
           And because your project requires project[extra1] and project[extra2], we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -1047,7 +1047,7 @@ fn extra_config_change_ignore_lockfile() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project[extra2] depends on sortedcontainers==2.4.0 and project[extra1] depends on sortedcontainers==2.3.0, we can conclude that project[extra1] and project[extra2] are incompatible.
+      ╰─▶ Because project[extra1] depends on sortedcontainers==2.3.0 and project[extra2] depends on sortedcontainers==2.4.0, we can conclude that project[extra1] and project[extra2] are incompatible.
           And because your project requires project[extra1] and project[extra2], we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -1289,9 +1289,9 @@ fn extra_nested_across_workspace() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because dummy[extra2] depends on proxy1[extra2] and only proxy1[extra2]==0.1.0 is available, we can conclude that dummy[extra2] depends on proxy1[extra2]==0.1.0.
-          And because proxy1[extra2]==0.1.0 depends on anyio==4.2.0 and proxy1[extra1]==0.1.0 depends on anyio==4.1.0, we can conclude that proxy1[extra1]==0.1.0 and dummy[extra2] are incompatible.
-          And because only proxy1[extra1]==0.1.0 is available and dummysub[extra1] depends on proxy1[extra1], we can conclude that dummysub[extra1] and dummy[extra2] are incompatible.
+      ╰─▶ Because proxy1[extra1]==0.1.0 depends on anyio==4.1.0 and proxy1[extra2]==0.1.0 depends on anyio==4.2.0, we can conclude that proxy1[extra1]==0.1.0 and proxy1[extra2]==0.1.0 are incompatible.
+          And because only proxy1[extra1]==0.1.0 is available and dummysub[extra1] depends on proxy1[extra1], we can conclude that dummysub[extra1] and proxy1[extra2]==0.1.0 are incompatible.
+          And because only proxy1[extra2]==0.1.0 is available and dummy[extra2] depends on proxy1[extra2], we can conclude that dummy[extra2] and dummysub[extra1] are incompatible.
           And because your workspace requires dummy[extra2] and dummysub[extra1], we can conclude that your workspace's requirements are unsatisfiable.
     "###);
 
@@ -1415,7 +1415,7 @@ fn group_basic() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project:group2 depends on sortedcontainers==2.4.0 and project:group1 depends on sortedcontainers==2.3.0, we can conclude that project:group1 and project:group2 are incompatible.
+      ╰─▶ Because project:group1 depends on sortedcontainers==2.3.0 and project:group2 depends on sortedcontainers==2.4.0, we can conclude that project:group1 and project:group2 are incompatible.
           And because your project requires project:group1 and project:group2, we can conclude that your project's requirements are unsatisfiable.
     "###);
 
@@ -1793,7 +1793,7 @@ fn mixed() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because project:group1 depends on sortedcontainers==2.3.0 and project[extra1] depends on sortedcontainers==2.4.0, we can conclude that project[extra1] and project:group1 are incompatible.
+      ╰─▶ Because project[extra1] depends on sortedcontainers==2.4.0 and project:group1 depends on sortedcontainers==2.3.0, we can conclude that project:group1 and project[extra1] are incompatible.
           And because your project requires project[extra1] and project:group1, we can conclude that your project's requirements are unsatisfiable.
     "###);
 

crates/uv/tests/it/lock_scenarios.rs

@@ -588,7 +588,7 @@ fn conflict_in_fork() -> Result<()> {
       × No solution found when resolving dependencies for split (sys_platform == 'darwin'):
       ╰─▶ Because only package-b==1.0.0 is available and package-b==1.0.0 depends on package-d==1, we can conclude that all versions of package-b depend on package-d==1.
           And because package-c==1.0.0 depends on package-d==2 and only package-c==1.0.0 is available, we can conclude that all versions of package-b and all versions of package-c are incompatible.
-          And because package-a{sys_platform == 'darwin'}==1.0.0 depends on package-b and package-c, we can conclude that package-a{sys_platform == 'darwin'}==1.0.0 cannot be used.
+          And because package-a==1.0.0 depends on package-b and package-c, we can conclude that package-a==1.0.0 cannot be used.
           And because only the following versions of package-a{sys_platform == 'darwin'} are available:
               package-a{sys_platform == 'darwin'}==1.0.0
               package-a{sys_platform == 'darwin'}>2
@@ -2940,7 +2940,7 @@ fn fork_non_local_fork_marker_direct() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies:
-      ╰─▶ Because package-a{sys_platform == 'linux'}==1.0.0 depends on package-c<2.0.0 and package-b{sys_platform == 'darwin'}==1.0.0 depends on package-c>=2.0.0, we can conclude that package-a{sys_platform == 'linux'}==1.0.0 and package-b{sys_platform == 'darwin'}==1.0.0 are incompatible.
+      ╰─▶ Because package-b==1.0.0 depends on package-c>=2.0.0 and package-a==1.0.0 depends on package-c<2.0.0, we can conclude that package-a==1.0.0 and package-b==1.0.0 are incompatible.
           And because your project depends on package-a{sys_platform == 'linux'}==1.0.0 and package-b{sys_platform == 'darwin'}==1.0.0, we can conclude that your project's requirements are unsatisfiable.
     "###
     );
@@ -3015,8 +3015,10 @@ fn fork_non_local_fork_marker_transitive() -> Result<()> {
       ╰─▶ Because package-a==1.0.0 depends on package-c{sys_platform == 'linux'}<2.0.0 and only the following versions of package-c{sys_platform == 'linux'} are available:
               package-c{sys_platform == 'linux'}==1.0.0
               package-c{sys_platform == 'linux'}>2.0.0
-          we can conclude that package-a==1.0.0 depends on package-c{sys_platform == 'linux'}==1.0.0.
-          And because only package-c{sys_platform == 'darwin'}<=2.0.0 is available and package-b==1.0.0 depends on package-c{sys_platform == 'darwin'}>=2.0.0, we can conclude that package-a==1.0.0 and package-b==1.0.0 are incompatible.
+          we can conclude that package-a==1.0.0 depends on package-c{sys_platform == 'linux'}==1.0.0. (1)
+
+          Because only package-c{sys_platform == 'darwin'}<=2.0.0 is available and package-b==1.0.0 depends on package-c{sys_platform == 'darwin'}>=2.0.0, we can conclude that package-b==1.0.0 depends on package-c==2.0.0.
+          And because we know from (1) that package-a==1.0.0 depends on package-c{sys_platform == 'linux'}==1.0.0, we can conclude that package-a==1.0.0 and package-b==1.0.0 are incompatible.
           And because your project depends on package-a==1.0.0 and package-b==1.0.0, we can conclude that your project's requirements are unsatisfiable.
     "###
     );

crates/uv/tests/it/pip_compile.rs

@@ -13622,9 +13622,9 @@ fn unsupported_requires_python_dynamic_metadata() -> Result<()> {
 
     ----- stderr -----
       × No solution found when resolving dependencies for split (python_full_version >= '3.10'):
-      ╰─▶ Because source-distribution{python_full_version >= '3.10'}==0.0.3 requires Python >=3.10 and you require source-distribution{python_full_version >= '3.10'}==0.0.3, we can conclude that your requirements are unsatisfiable.
+      ╰─▶ Because source-distribution==0.0.3 requires Python >=3.10 and you require source-distribution{python_full_version >= '3.10'}==0.0.3, we can conclude that your requirements are unsatisfiable.
 
-          hint: The source distribution for `source-distribution{python_full_version >= '3.10'}` (v0.0.3) does not include static metadata. Generating metadata for this package requires Python >=3.10, but Python 3.8.[X] is installed.
+          hint: The source distribution for `source-distribution` (v0.0.3) does not include static metadata. Generating metadata for this package requires Python >=3.10, but Python 3.8.[X] is installed.
     "###);
 
     Ok(())