Remove double-proxy nodes in error reporting

crates/uv-resolver/src/error.rs

@@ -2,7 +2,7 @@ use std::collections::{BTreeMap, BTreeSet};
 use std::fmt::Formatter;
 use std::sync::Arc;
 
-use pubgrub::{DefaultStringReporter, DerivationTree, External, Range, Reporter};
+use pubgrub::{DefaultStringReporter, DerivationTree, Derived, External, Range, Reporter};
 use rustc_hash::FxHashMap;
 
 use distribution_types::{BuiltDist, IndexLocations, InstalledDist, SourceDist};
@@ -13,9 +13,7 @@ use uv_normalize::PackageName;
 use crate::candidate_selector::CandidateSelector;
 use crate::dependency_provider::UvDependencyProvider;
 use crate::fork_urls::ForkUrls;
-use crate::pubgrub::{
- PubGrubPackage, PubGrubPackageInner, PubGrubReportFormatter, PubGrubSpecifierError,
-};
+use crate::pubgrub::{PubGrubPackage, PubGrubReportFormatter, PubGrubSpecifierError};
 use crate::python_requirement::PythonRequirement;
 use crate::resolver::{IncompletePackage, ResolverMarkers, UnavailablePackage, UnavailableReason};
 
@@ -113,6 +111,8 @@ impl<T> From<tokio::sync::mpsc::error::SendError<T>> for ResolveError {
  }
 }
 
+pub(crate) type ErrorTree = DerivationTree<PubGrubPackage, Range<Version>, UnavailableReason>;
+
 /// A wrapper around [`pubgrub::error::NoSolutionError`] that displays a resolution failure report.
 #[derive(Debug)]
 pub struct NoSolutionError {
@@ -165,49 +165,46 @@ impl NoSolutionError {
 
  /// Given a [`DerivationTree`], collapse any [`External::FromDependencyOf`] incompatibilities
  /// wrap an [`PubGrubPackageInner::Extra`] package.
- pub(crate) fn collapse_proxies(
- derivation_tree: &mut DerivationTree<PubGrubPackage, Range<Version>, UnavailableReason>,
- ) {
- match derivation_tree {
- DerivationTree::External(_) => {}
- DerivationTree::Derived(derived) => {
- match (
- Arc::make_mut(&mut derived.cause1),
- Arc::make_mut(&mut derived.cause2),
- ) {
- (
- DerivationTree::External(External::FromDependencyOf(package, ..)),
- ref mut cause,
- ) if matches!(
- &**package,
- PubGrubPackageInner::Extra { .. }
- | PubGrubPackageInner::Marker { .. }
- | PubGrubPackageInner::Dev { .. }
- ) =>
- {
- Self::collapse_proxies(cause);
- *derivation_tree = cause.clone();
- }
- (
- ref mut cause,
- DerivationTree::External(External::FromDependencyOf(package, ..)),
- ) if matches!(
- &**package,
- PubGrubPackageInner::Extra { .. }
- | PubGrubPackageInner::Marker { .. }
- | PubGrubPackageInner::Dev { .. }
- ) =>
- {
- Self::collapse_proxies(cause);
- *derivation_tree = cause.clone();
- }
- _ => {
- Self::collapse_proxies(Arc::make_mut(&mut derived.cause1));
- Self::collapse_proxies(Arc::make_mut(&mut derived.cause2));
+ pub(crate) fn collapse_proxies(derivation_tree: ErrorTree) -> ErrorTree {
+ fn collapse(derivation_tree: ErrorTree) -> Option<ErrorTree> {
+ match derivation_tree {
+ DerivationTree::Derived(derived) => {
+ match (&*derived.cause1, &*derived.cause2) {
+ (
+ DerivationTree::External(External::FromDependencyOf(package1, ..)),
+ DerivationTree::External(External::FromDependencyOf(package2, ..)),
+ ) if package1.is_proxy() && package2.is_proxy() => None,
+ (
+ DerivationTree::External(External::FromDependencyOf(package, ..)),
+ cause,
+ ) if package.is_proxy() => collapse(cause.clone()),
+ (
+ cause,
+ DerivationTree::External(External::FromDependencyOf(package, ..)),
+ ) if package.is_proxy() => collapse(cause.clone()),
+ (cause1, cause2) => {
+ let cause1 = collapse(cause1.clone());
+ let cause2 = collapse(cause2.clone());
+ match (cause1, cause2) {
+ (Some(cause1), Some(cause2)) => {
+ Some(DerivationTree::Derived(Derived {
+ cause1: Arc::new(cause1),
+ cause2: Arc::new(cause2),
+ ..derived
+ }))
+ }
+ (Some(cause), None) | (None, Some(cause)) => Some(cause),
+ _ => None,
+ }
+ }
  }
  }
+ DerivationTree::External(_) => Some(derivation_tree),
  }
  }
+
+ collapse(derivation_tree)
+ .expect("derivation tree should contain at least one external term")
  }
 }
 

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

@@ -159,6 +159,16 @@ impl PubGrubPackage {
  PubGrubPackageInner::Marker { marker, .. } => Some(marker),
  }
  }
+
+ /// Returns `true` if this PubGrub package is a proxy package.
+ pub fn is_proxy(&self) -> bool {
+ matches!(
+ &**self,
+ PubGrubPackageInner::Extra { .. }
+ | PubGrubPackageInner::Dev { .. }
+ | PubGrubPackageInner::Marker { .. }
+ )
+ }
 }
 
 #[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Hash, Ord)]

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

@@ -14,6 +14,7 @@ use pep440_rs::Version;
 use uv_normalize::PackageName;
 
 use crate::candidate_selector::CandidateSelector;
+use crate::error::ErrorTree;
 use crate::fork_urls::ForkUrls;
 use crate::prerelease::AllowPrerelease;
 use crate::python_requirement::{PythonRequirement, PythonTarget};
@@ -399,7 +400,7 @@ impl PubGrubReportFormatter<'_> {
  /// their requirements.
  pub(crate) fn hints(
  &self,
- derivation_tree: &DerivationTree<PubGrubPackage, Range<Version>, UnavailableReason>,
+ derivation_tree: &ErrorTree,
  selector: &CandidateSelector,
  index_locations: &IndexLocations,
  unavailable_packages: &FxHashMap<PackageName, UnavailablePackage>,

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

@@ -1905,7 +1905,7 @@ impl<InstalledPackages: InstalledPackagesProvider> ResolverState<InstalledPackag
  visited: &FxHashSet<PackageName>,
  index_locations: &IndexLocations,
  ) -> ResolveError {
- NoSolutionError::collapse_proxies(&mut err);
+ err = NoSolutionError::collapse_proxies(err);
 
  let mut unavailable_packages = FxHashMap::default();
  for package in err.packages() {

crates/uv/tests/pip_compile.rs

@@ -6803,8 +6803,7 @@ fn universal_multi_version() -> Result<()> {
 
  ----- stderr -----
  × No solution found when resolving dependencies:
- ╰─▶ Because iniconfig{python_version > '3.12'}==2.0.0 depends on iniconfig==2.0.0 and you require iniconfig{python_version > '3.12'}==2.0.0, we can conclude that your requirements and iniconfig{python_version == '3.12'}==1.0.0 are incompatible.
- And because you require iniconfig{python_version == '3.12'}==1.0.0, we can conclude that the requirements are unsatisfiable.
+ ╰─▶ Because you require iniconfig{python_version > '3.12'}==2.0.0 and iniconfig{python_version == '3.12'}==1.0.0, we can conclude that the requirements are unsatisfiable.
  "###
  );