feat: notify which conda packages may have influenced the conflict

src/lock_file/resolve/pypi.rs

@@ -1,6 +1,6 @@
 use std::{
     cell::RefCell,
-    collections::HashMap,
+    collections::{HashMap, HashSet},
     iter::once,
     ops::Deref,
     path::{Path, PathBuf},
@@ -46,7 +46,7 @@ use uv_pypi_types::{Conflicts, HashAlgorithm, HashDigests};
 use uv_requirements::LookaheadResolver;
 use uv_resolver::{
     AllowedYanks, DefaultResolverProvider, FlatIndex, InMemoryIndex, Manifest, Options, Preference,
-    PreferenceError, Preferences, PythonRequirement, Resolver, ResolverEnvironment,
+    PreferenceError, Preferences, PythonRequirement, ResolveError, Resolver, ResolverEnvironment,
 };
 use uv_types::EmptyInstalledPackages;
 
@@ -202,6 +202,60 @@ fn print_overridden_requests(package_requests: &HashMap<uv_normalize::PackageNam
     }
 }
 
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum SolveError {
+    #[error("failed to resolve pypi dependencies")]
+    NoSolution {
+        source: Box<uv_resolver::NoSolutionError>,
+        #[help]
+        advice: Option<String>,
+    },
+    #[error("failed to resolve pypi dependencies")]
+    Other(#[from] ResolveError),
+}
+
+/// Creates a custom `SolveError` from a `ResolveError`.
+/// to add some extra information about locked conda packages
+fn create_solve_error(
+    error: ResolveError,
+    conda_python_packages: &CondaPythonPackages,
+) -> SolveError {
+    match error {
+        ResolveError::NoSolution(no_solution) => {
+            let packages: HashSet<_> = no_solution.packages().collect();
+            let conflicting_packages: Vec<String> = conda_python_packages
+                .iter()
+                .filter_map(|(pypi_name, (_, pypi_identifier))| {
+                    if packages.contains(pypi_name) {
+                        Some(format!(
+                            "{}=={}",
+                            pypi_identifier.name.as_source(),
+                            pypi_identifier.version
+                        ))
+                    } else {
+                        None
+                    }
+                })
+                .collect();
+
+            let advice = if conflicting_packages.is_empty() {
+                None
+            } else {
+                Some(format!(
+                    "The following PyPI packages have been pinned by the conda solve, and this version may be causing a conflict:\n{}",
+                    conflicting_packages.join("\n")
+                ))
+            };
+
+            SolveError::NoSolution {
+                source: no_solution,
+                advice,
+            }
+        }
+        _ => SolveError::Other(error),
+    }
+}
+
 #[allow(clippy::too_many_arguments)]
 pub async fn resolve_pypi(
     context: UvResolutionContext,
@@ -574,8 +628,7 @@ pub async fn resolve_pypi(
     ))
     .resolve()
     .await
-    .into_diagnostic()
-    .context("failed to resolve pypi dependencies")?;
+    .map_err(|e| create_solve_error(e, &conda_python_packages))?;
     let resolution = Resolution::from(resolution);
 
     // Print the overridden package requests

tests/integration_rust/pypi_tests.rs

@@ -423,3 +423,36 @@ async fn test_cross_platform_resolve_with_no_build() {
             .join("foo-1.0.0-py2.py3-none-any.whl")
     );
 }
+
+/// This test checks that the help message is correctly generated when a PyPI package is pinned
+/// by the conda solve, which may cause a conflict with the PyPI dependencies.
+///
+/// We expect there to be a help message that informs the user about the pinned package
+#[tokio::test]
+#[cfg_attr(not(feature = "slow_integration_tests"), ignore)]
+async fn test_pinned_help_message() {
+    let pixi = PixiControl::from_manifest(
+        r#"
+        [workspace]
+        channels = ["https://prefix.dev/conda-forge"]
+        name = "deleteme"
+        platforms = ["linux-64"]
+        version = "0.1.0"
+
+        [dependencies]
+        python = "3.12.*"
+        pandas = "*"
+
+        [pypi-dependencies]
+        databricks-sql-connector = ">=4.0.0"
+        "#,
+    );
+    // First, it should fail
+    let result = pixi.unwrap().update_lock_file().await;
+    let err = result.err().unwrap();
+    // Second, it should contain a help message
+    assert_eq!(
+        format!("{}", err.help().unwrap()),
+        "The following PyPI packages have been pinned by the conda solve, and this version may be causing a conflict:\npandas==2.3.1"
+    );
+}