Improve handling of dependency conflicts resulting in empty version ranges

crates/puffin-cli/tests/snapshots/pip_compile__compile_constraints_inline.snap

@@ -6,16 +6,17 @@ info:
     - pip-compile
     - requirements.in
     - "--cache-dir"
-    - /var/folders/nt/6gf2v7_s3k13zq_t3944rwz40000gn/T/.tmp5R6H5M
+    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpmkb9tv
   env:
-    VIRTUAL_ENV: /var/folders/nt/6gf2v7_s3k13zq_t3944rwz40000gn/T/.tmpIdL1TH/.venv
+    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpO0ihlM/.venv
 ---
 success: true
 exit_code: 0
 ----- stdout -----
 # This file was autogenerated by Puffin v0.0.1 via the following command:
 #    [BIN_PATH] pip-compile requirements.in --cache-dir [CACHE_DIR]
+sqlparse==0.4.3
 
 ----- stderr -----
-Resolved 0 packages in [TIME]
+Resolved 1 package in [TIME]
 

crates/puffin-cli/tests/snapshots/pip_compile__compile_constraints_markers.snap

@@ -8,9 +8,9 @@ info:
     - "--constraint"
     - constraints.txt
     - "--cache-dir"
-    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmp1Ts53o
+    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmp6Agh9o
   env:
-    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmp1vzBQa/.venv
+    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmp2l1dM3/.venv
 ---
 success: true
 exit_code: 0
@@ -21,7 +21,9 @@ anyio==4.0.0
 idna==3.4
     # via anyio
 sniffio==1.3.0
-    # via anyio
+    # via
+    #   anyio
+    #   idna
 
 ----- stderr -----
 Resolved 3 packages in [TIME]

crates/puffin-cli/tests/snapshots/pip_compile__compile_constraints_txt.snap

@@ -8,9 +8,9 @@ info:
     - "--constraint"
     - constraints.txt
     - "--cache-dir"
-    - /var/folders/nt/6gf2v7_s3k13zq_t3944rwz40000gn/T/.tmpvjdHOb
+    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpVzXpee
   env:
-    VIRTUAL_ENV: /var/folders/nt/6gf2v7_s3k13zq_t3944rwz40000gn/T/.tmpSAaWi3/.venv
+    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpYmxcVz/.venv
 ---
 success: true
 exit_code: 0
@@ -21,7 +21,9 @@ asgiref==3.7.2
     # via django
 django==5.0b1
 sqlparse==0.4.3
-    # via django
+    # via
+    #   asgiref
+    #   django
 
 ----- stderr -----
 Resolved 3 packages in [TIME]

crates/puffin-cli/tests/snapshots/pip_compile__compile_unsolvable_requirements.snap

@@ -6,15 +6,16 @@ info:
     - pip-compile
     - pyproject.toml
     - "--cache-dir"
-    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpN531dN
+    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpRAI4mN
   env:
-    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmp99w9dK/.venv
+    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpvNCp98/.venv
 ---
 success: false
 exit_code: 1
 ----- stdout -----
 
 ----- stderr -----
   × No solution found when resolving dependencies:
-  ╰─▶ my-project depends on django∅
+  ╰─▶ Because my-project depends on django==5.0b1 and my-project depends on
+      django==5.0a1, version solving failed.
 

crates/puffin-cli/tests/snapshots/pip_compile__conflicting_repeated_url_dependency_version_mismatch.snap

@@ -6,14 +6,21 @@ info:
     - pip-compile
     - requirements.in
     - "--cache-dir"
-    - /var/folders/nt/6gf2v7_s3k13zq_t3944rwz40000gn/T/.tmpPGmK15
+    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpur3UYY
   env:
-    VIRTUAL_ENV: /var/folders/nt/6gf2v7_s3k13zq_t3944rwz40000gn/T/.tmpgXUIr9/.venv
+    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpBlhDHf/.venv
 ---
 success: false
-exit_code: 2
+exit_code: 1
 ----- stdout -----
 
 ----- stderr -----
-error: Conflicting URLs for package `werkzeug`: https://files.pythonhosted.org/packages/bd/24/11c3ea5a7e866bf2d97f0501d0b4b1c9bbeade102bb4b588f0d2919a5212/Werkzeug-2.0.1-py3-none-any.whl and https://files.pythonhosted.org/packages/ff/1d/960bb4017c68674a1cb099534840f18d3def3ce44aed12b5ed8b78e0153e/Werkzeug-2.0.0-py3-none-any.whl
+  × No solution found when resolving dependencies:
+  ╰─▶ Because root depends on werkzeug @ https://
+      files.pythonhosted.org/packages/
+      bd/24/11c3ea5a7e866bf2d97f0501d0b4b1c9bbeade102bb4b588f0d2919a5212/
+      Werkzeug-2.0.1-py3-none-any.whl==0 and root depends
+      on werkzeug @ https://files.pythonhosted.org/packages/
+      ff/1d/960bb4017c68674a1cb099534840f18d3def3ce44aed12b5ed8b78e0153e/
+      Werkzeug-2.0.0-py3-none-any.whl==1, version solving failed.
 

crates/puffin-cli/tests/snapshots/pip_compile__conflicting_transitive_url_dependency.snap

@@ -6,17 +6,17 @@ info:
     - pip-compile
     - requirements.in
     - "--cache-dir"
-    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpMkgmyj
+    - /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpvfszXx
   env:
-    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpGndWSU/.venv
+    VIRTUAL_ENV: /var/folders/bc/qlsk3t6x7c9fhhbvvcg68k9c0000gp/T/.tmpf7Zv4n/.venv
 ---
 success: false
 exit_code: 1
 ----- stdout -----
 
 ----- stderr -----
   × No solution found when resolving dependencies:
-  ╰─▶ Because there is no version of werkzeug available matching >=3.0.0 and
-      flask==3.0.0 depends on werkzeug>=3.0.0, flask==3.0.0 is forbidden.
+  ╰─▶ Because flask==3.0.0 depends on werkzeug>=3.0.0 and there is no version
+      of werkzeug available matching >=3.0.0, flask==3.0.0 is forbidden.
       And because root depends on flask==3.0.0, version solving failed.
 

crates/puffin-resolver/src/pubgrub/dependencies.rs

@@ -1,29 +1,28 @@
-use fxhash::FxHashMap;
 use itertools::Itertools;
 use pubgrub::range::Range;
 use tracing::warn;
 
 use pep508_rs::{MarkerEnvironment, Requirement, VersionOrUrl};
-use puffin_cache::CanonicalUrl;
+
 use puffin_normalize::{ExtraName, PackageName};
 
 use crate::pubgrub::specifier::PubGrubSpecifier;
 use crate::pubgrub::{PubGrubPackage, PubGrubVersion};
 use crate::ResolveError;
 
 #[derive(Debug)]
-pub struct PubGrubDependencies(FxHashMap<PubGrubPackage, Range<PubGrubVersion>>);
+pub struct PubGrubDependencies(Vec<(PubGrubPackage, Range<PubGrubVersion>)>);
 
 impl PubGrubDependencies {
-    /// Generate a set of `PubGrub` dependencies from a set of requirements.
+    /// Generate a collection of `PubGrub` dependencies from a collection of requirements.
     pub(crate) fn try_from_requirements<'a>(
         requirements: &[Requirement],
         constraints: &[Requirement],
         extra: Option<&'a ExtraName>,
         source: Option<&'a PackageName>,
         env: &'a MarkerEnvironment,
     ) -> Result<Self, ResolveError> {
-        let mut dependencies = FxHashMap::<PubGrubPackage, Range<PubGrubVersion>>::default();
+        let mut dependencies = Vec::new();
 
         // Iterate over all declared requirements.
         for requirement in requirements {
@@ -55,21 +54,7 @@ impl PubGrubDependencies {
                     .map(|extra| to_pubgrub(requirement, Some(extra))),
             ) {
                 let (package, version) = result?;
-
-                if let Some(entry) = dependencies.get_key_value(&package) {
-                    // Merge the versions.
-                    let version = merge_versions(entry.1, &version);
-
-                    // Merge the package.
-                    if let Some(package) = merge_package(entry.0, &package)? {
-                        dependencies.remove(&package);
-                        dependencies.insert(package, version);
-                    } else {
-                        dependencies.insert(package, version);
-                    }
-                } else {
-                    dependencies.insert(package.clone(), version.clone());
-                }
+                dependencies.push((package.clone(), version.clone()));
             }
         }
 
@@ -103,41 +88,26 @@ impl PubGrubDependencies {
                     .map(|extra| to_pubgrub(constraint, Some(extra))),
             ) {
                 let (package, version) = result?;
-
-                if let Some(entry) = dependencies.get_key_value(&package) {
-                    // Merge the versions.
-                    let version = merge_versions(entry.1, &version);
-
-                    // Merge the package.
-                    if let Some(package) = merge_package(entry.0, &package)? {
-                        dependencies.insert(package, version);
-                    } else {
-                        dependencies.insert(package, version);
-                    }
-                }
+                dependencies.push((package.clone(), version.clone()));
             }
         }
 
         Ok(Self(dependencies))
     }
 
-    /// Insert a [`PubGrubPackage`] and [`PubGrubVersion`] range into the set of dependencies.
-    pub(crate) fn insert(
-        &mut self,
-        package: PubGrubPackage,
-        version: Range<PubGrubVersion>,
-    ) -> Option<Range<PubGrubVersion>> {
-        self.0.insert(package, version)
+    // Add a [`PubGrubPackage`] and [`PubGrubVersion`] range into the dependencies.
+    pub(crate) fn push(&mut self, package: PubGrubPackage, version: Range<PubGrubVersion>) {
+        self.0.push((package, version))
     }
 
     /// Iterate over the dependencies.
-    pub(crate) fn iter(&self) -> impl Iterator<Item = (&PubGrubPackage, &Range<PubGrubVersion>)> {
+    pub(crate) fn iter(&self) -> impl Iterator<Item = &(PubGrubPackage, Range<PubGrubVersion>)> {
         self.0.iter()
     }
 }
 
-/// Convert a [`PubGrubDependencies`] to a [`DependencyConstraints`].
-impl From<PubGrubDependencies> for FxHashMap<PubGrubPackage, Range<PubGrubVersion>> {
+/// Convert a [`PubGrubDependencies`] to a [`Vec`].
+impl From<PubGrubDependencies> for Vec<(PubGrubPackage, Range<PubGrubVersion>)> {
     fn from(dependencies: PubGrubDependencies) -> Self {
         dependencies.0
     }
@@ -174,61 +144,3 @@ fn to_pubgrub(
         }
     }
 }
-
-/// Merge two [`PubGrubVersion`] ranges.
-fn merge_versions(
-    left: &Range<PubGrubVersion>,
-    right: &Range<PubGrubVersion>,
-) -> Range<PubGrubVersion> {
-    left.intersection(right)
-}
-
-/// Merge two [`PubGrubPackage`] instances.
-fn merge_package(
-    left: &PubGrubPackage,
-    right: &PubGrubPackage,
-) -> Result<Option<PubGrubPackage>, ResolveError> {
-    match (left, right) {
-        // Either package is `root`.
-        (PubGrubPackage::Root(_), _) | (_, PubGrubPackage::Root(_)) => Ok(None),
-
-        // Left package has a URL. Propagate the URL.
-        (PubGrubPackage::Package(name, extra, Some(url)), PubGrubPackage::Package(.., None)) => {
-            Ok(Some(PubGrubPackage::Package(
-                name.clone(),
-                extra.clone(),
-                Some(url.clone()),
-            )))
-        }
-
-        // Right package has a URL.
-        (PubGrubPackage::Package(.., None), PubGrubPackage::Package(name, extra, Some(url))) => {
-            Ok(Some(PubGrubPackage::Package(
-                name.clone(),
-                extra.clone(),
-                Some(url.clone()),
-            )))
-        }
-
-        // Neither package has a URL.
-        (PubGrubPackage::Package(_name, _extra, None), PubGrubPackage::Package(.., None)) => {
-            Ok(None)
-        }
-
-        // Both packages have a URL.
-        (
-            PubGrubPackage::Package(name, _extra, Some(left)),
-            PubGrubPackage::Package(.., Some(right)),
-        ) => {
-            if CanonicalUrl::new(left) == CanonicalUrl::new(right) {
-                Ok(None)
-            } else {
-                Err(ResolveError::ConflictingUrls(
-                    name.clone(),
-                    left.to_string(),
-                    right.to_string(),
-                ))
-            }
-        }
-    }
-}

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

@@ -68,6 +68,13 @@ pub enum PubGrubPackage {
         #[derivative(Hash = "ignore")]
         Option<Url>,
     ),
+    Url(
+        PackageName,
+        #[derivative(PartialEq = "ignore")]
+        #[derivative(PartialOrd = "ignore")]
+        #[derivative(Hash = "ignore")]
+        Url,
+    ),
 }
 
 impl std::fmt::Display for PubGrubPackage {
@@ -84,6 +91,7 @@ impl std::fmt::Display for PubGrubPackage {
             PubGrubPackage::Package(name, Some(extra), ..) => {
                 write!(f, "{name}[{extra}]")
             }
+            PubGrubPackage::Url(name, url) => write!(f, "{name} @ {url}"),
         }
     }
 }

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

@@ -26,6 +26,7 @@ impl PubGrubPriorities {
                 .copied()
                 .map(|priority| priority + 1)
                 .map(Reverse),
+            PubGrubPackage::Url(..) => None,
         }
     }
 }