uv-resolver: add filtering step after forks are combined

While we do filter based on Python markers during forking, it turns out
that the markers for each fork are "combined" *after* this filtering
step. But the process of combination can result in a more specific
marker that is always false for the configured Python requirement. This
could result in dependencies with markers that are always false (like
`python_version < '0'`) appearing in the resolution.

I think it would probably be better to do this check during forking, but
that's a bit of a bigger refactor.

Author: BurntSushi

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

@@ -316,7 +316,9 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
                     fork_preferences
                         .iter()
                         .rev()
-                        .map(|fork_preference| state.clone().with_markers(fork_preference.clone()))
+                        .filter_map(|fork_preference| {
+                            state.clone().with_markers(fork_preference.clone())
+                        })
                         .collect()
                 }
             } else {
@@ -693,14 +695,17 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
         forks
             .into_iter()
             .enumerate()
-            .map(move |(i, fork)| {
+            .filter_map(move |(i, fork)| {
                 let is_last = i == forks_len - 1;
                 let forked_state = cur_state.take().unwrap();
                 if !is_last {
                     cur_state = Some(forked_state.clone());
                 }
 
-                let mut forked_state = forked_state.with_markers(fork.markers);
+                let markers = fork.markers.clone();
+                Some((fork, forked_state.with_markers(markers)?))
+            })
+            .map(move |(fork, mut forked_state)| {
                 forked_state.add_package_version_dependencies(
                     for_package,
                     version,
@@ -2320,8 +2325,16 @@ impl ForkState {
 
     /// Subset the current markers with the new markers and update the python requirements fields
     /// accordingly.
-    fn with_markers(mut self, markers: MarkerTree) -> Self {
+    fn with_markers(mut self, markers: MarkerTree) -> Option<Self> {
         let combined_markers = self.markers.and(markers);
+        let python_marker = self.python_requirement.to_marker_tree();
+        if combined_markers.is_disjoint(&python_marker) {
+            debug!(
+                "Skipping split {combined_markers:?} \
+                 because of Python requirement {python_marker:?}",
+            );
+            return None;
+        }
 
         // If the fork contains a narrowed Python requirement, apply it.
         let python_requirement = marker::requires_python(&combined_markers)
@@ -2335,7 +2348,7 @@ impl ForkState {
         }
 
         self.markers = ResolverMarkers::Fork(combined_markers);
-        self
+        Some(self)
     }
 
     fn into_resolution(self) -> Resolution {

crates/uv/tests/it/pip_compile.rs

@@ -484,14 +484,10 @@ typing_extensions==4.3.0
     apache-airflow==2.3.4     # via apache-airflow-providers-microsoft-azure, -r requirements.in
     apache-airflow-providers-common-sql==1.4.0  # via apache-airflow-providers-sqlite
     apache-airflow-providers-ftp==3.3.1  # via apache-airflow
-    apache-airflow-providers-ftp==3.7.0 ; python_version < '0'  # via apache-airflow
     apache-airflow-providers-http==4.3.0  # via apache-airflow
-    apache-airflow-providers-http==4.10.0 ; python_version < '0'  # via apache-airflow
     apache-airflow-providers-imap==3.1.1  # via apache-airflow
-    apache-airflow-providers-imap==3.5.0 ; python_version < '0'  # via apache-airflow
     apache-airflow-providers-microsoft-azure==4.2.0  # via apache-airflow, -c constraints.txt
     apache-airflow-providers-sqlite==3.3.2  # via apache-airflow
-    apache-airflow-providers-sqlite==3.7.1 ; python_version < '0'  # via apache-airflow
     apispec==3.3.2            # via flask-appbuilder
     argcomplete==3.2.3        # via apache-airflow
     asgiref==3.8.1            # via apache-airflow-providers-http, connexion, flask
@@ -501,13 +497,10 @@ typing_extensions==4.3.0
     azure-batch==14.1.0       # via apache-airflow-providers-microsoft-azure
     azure-common==1.1.28      # via azure-batch, azure-keyvault-secrets, azure-mgmt-containerinstance, azure-mgmt-datafactory, azure-mgmt-datalake-store, azure-mgmt-resource, azure-storage-common, azure-storage-file
     azure-core==1.29.1        # via azure-cosmos, azure-identity, azure-keyvault-secrets, azure-mgmt-core, azure-servicebus, azure-storage-blob, msrest
-    azure-core==1.30.1 ; python_version < '0'  # via azure-identity
     azure-cosmos==4.5.1       # via apache-airflow-providers-microsoft-azure
-    azure-cosmos==4.6.0 ; python_version < '0'  # via apache-airflow-providers-microsoft-azure
     azure-datalake-store==0.0.53  # via apache-airflow-providers-microsoft-azure
     azure-identity==1.10.0    # via apache-airflow-providers-microsoft-azure, -c constraints.txt
     azure-keyvault-secrets==4.7.0  # via apache-airflow-providers-microsoft-azure
-    azure-keyvault-secrets==4.8.0 ; python_version < '0'  # via apache-airflow-providers-microsoft-azure
     azure-kusto-data==0.0.45  # via apache-airflow-providers-microsoft-azure
     azure-mgmt-containerinstance==1.5.0  # via apache-airflow-providers-microsoft-azure
     azure-mgmt-core==1.4.0    # via azure-mgmt-datafactory, azure-mgmt-resource
@@ -523,11 +516,9 @@ typing_extensions==4.3.0
     azure-storage-file==2.1.0  # via apache-airflow-providers-microsoft-azure
     babel==2.14.0             # via flask-babel
     black==22.12.0            # via -r requirements.in
-    black==24.3.0 ; python_version < '0'  # via -r requirements.in
     blinker==1.7.0            # via apache-airflow
     cachelib==0.9.0           # via flask-caching
     cattrs==23.1.2            # via apache-airflow
-    cattrs==23.2.3 ; python_version < '0'  # via apache-airflow
     certifi==2024.2.2         # via httpcore, httpx, msrest, requests
     cffi==1.16.0              # via azure-datalake-store, cryptography
     charset-normalizer==3.3.2  # via requests
@@ -571,7 +562,6 @@ typing_extensions==4.3.0
     jinja2==3.1.3             # via apache-airflow, connexion, flask, flask-babel, python-nvd3, swagger-ui-bundle
     joblib==1.3.2             # via scikit-learn
     jsonschema==4.17.3        # via apache-airflow, connexion, flask-appbuilder
-    jsonschema==4.21.1 ; python_version < '0'  # via apache-airflow, flask-appbuilder
     lazy-object-proxy==1.10.0  # via apache-airflow
     linkify-it-py==2.0.3      # via apache-airflow
     lockfile==0.12.2          # via apache-airflow, python-daemon
@@ -626,7 +616,6 @@ typing_extensions==4.3.0
     requests-oauthlib==2.0.0  # via msrest
     requests-toolbelt==1.0.0  # via apache-airflow-providers-http
     rich==13.3.1              # via apache-airflow
-    rich==13.7.1 ; python_version < '0'  # via apache-airflow
     scikit-learn==1.2.2       # via -r requirements.in
     scipy==1.12.0             # via scikit-learn
     setproctitle==1.3.3       # via apache-airflow
@@ -660,7 +649,7 @@ typing_extensions==4.3.0
     yarl==1.9.4               # via aiohttp
 
     ----- stderr -----
-    Resolved 183 packages in [TIME]
+    Resolved 172 packages in [TIME]
     "###
     );