Consolidate UnusableDependencies into a generic Unavailable incompatibility (#1088)

Requires astral-sh/pubgrub#20

In short, `UnusableDependencies` can be generalized into `Unavailable`
which encompasses incompatibilities where a package range which is
unusable for some inherent reason as well as when its dependencies are
unusable. We can eventually use this to track more incompatibilities in
the solver. I made the reason string required because I can't see a case
where we should leave it out.

Additionally, this improves the display of conflicts in the root
requirements.

Author: zanieb

Cargo.lock

@@ -53,7 +53,7 @@ owo-colors = { version = "3.5.0" }
 petgraph = { version = "0.6.4" }
 platform-info = { version = "2.0.2" }
 plist = { version = "1.6.0" }
-pubgrub = { git = "https://github.com/zanieb/pubgrub", rev = "0e02ea9fc8d021fb6a6b9e77b09ade4332068f42" }
+pubgrub = { git = "https://github.com/zanieb/pubgrub", rev = "7a573e3902ff338abdcf3b87682e4c6d04845f2f" }
 pyo3 = { version = "0.20.2" }
 pyo3-log = { version = "0.9.0"}
 pyproject-toml = { version = "0.8.1" }

Cargo.toml

@@ -49,10 +49,10 @@ pub enum ResolveError {
     #[error("~= operator requires at least two release segments: {0}")]
     InvalidTildeEquals(pep440_rs::VersionSpecifier),
 
-    #[error("Conflicting URLs for package `{0}`:\n- {1}\n- {2}")]
+    #[error("There are conflicting URLs for package `{0}`:\n- {1}\n- {2}")]
     ConflictingUrls(PackageName, String, String),
 
-    #[error("Conflicting versions for `{0}`: {1}")]
+    #[error("There are conflicting versions for `{0}`: {1}")]
     ConflictingVersions(String, String),
 
     #[error("Package `{0}` attempted to resolve via URL: {1}. URL dependencies must be expressed as direct requirements or constraints. Consider adding `{0} @ {1}` to your dependencies or constraints file.")]

crates/puffin-resolver/src/error.rs

@@ -96,32 +96,18 @@ impl ReportFormatter<PubGrubPackage, Range<Version>> for PubGrubReportFormatter<
                     }
                 }
             }
-            External::UnavailableDependencies(package, set) => {
-                let set = self.simplify_set(set, package);
-                format!(
-                    "dependencies of {}are unavailable",
-                    Padded::new("", &PackageRange::compatibility(package, &set), " ")
-                )
-            }
-            External::UnusableDependencies(package, set, reason) => {
-                if let Some(reason) = reason {
-                    if matches!(package, PubGrubPackage::Root(_)) {
-                        format!("{package} dependencies are unusable: {reason}")
-                    } else {
-                        let set = self.simplify_set(set, package);
-                        format!(
-                            "dependencies of {}are unusable: {reason}",
-                            Padded::new("", &PackageRange::compatibility(package, &set), " ")
-                        )
-                    }
-                } else {
-                    let set = self.simplify_set(set, package);
-                    format!(
-                        "dependencies of {}are unusable",
-                        Padded::new("", &PackageRange::compatibility(package, &set), " ")
-                    )
+            External::Unavailable(package, set, reason) => match package {
+                PubGrubPackage::Root(Some(name)) => {
+                    format!("{name} cannot be used because {reason}")
                 }
-            }
+                PubGrubPackage::Root(None) => {
+                    format!("your requirements cannot be used because {reason}")
+                }
+                _ => format!(
+                    "{}is unusable because {reason}",
+                    Padded::new("", &PackageRange::compatibility(package, set), " ")
+                ),
+            },
             External::FromDependencyOf(package, package_set, dependency, dependency_set) => {
                 let package_set = self.simplify_set(package_set, package);
                 let dependency_set = self.simplify_set(dependency_set, dependency);
@@ -403,8 +389,7 @@ impl PubGrubReportFormatter<'_> {
                     }
                 }
                 External::NotRoot(..) => {}
-                External::UnavailableDependencies(..) => {}
-                External::UnusableDependencies(..) => {}
+                External::Unavailable(..) => {}
                 External::FromDependencyOf(..) => {}
             },
             DerivationTree::Derived(derived) => {

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

@@ -335,22 +335,30 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
                     .get_dependencies(package, &version, &mut priorities, request_sink)
                     .await?
                 {
-                    Dependencies::Unusable(reason) => {
-                        state.add_incompatibility(Incompatibility::unusable_dependencies(
+                    Dependencies::Unavailable(reason) => {
+                        let message = {
+                            if matches!(package, PubGrubPackage::Root(_)) {
+                                // Including front-matter for the root package is redundant
+                                reason.clone()
+                            } else {
+                                format!("its dependencies are unusable because {reason}")
+                            }
+                        };
+                        state.add_incompatibility(Incompatibility::unavailable(
                             package.clone(),
                             version.clone(),
-                            reason.clone(),
+                            message,
                         ));
                         continue;
                     }
-                    Dependencies::Known(constraints) if constraints.contains_key(package) => {
+                    Dependencies::Available(constraints) if constraints.contains_key(package) => {
                         return Err(PubGrubError::SelfDependency {
                             package: package.clone(),
                             version: version.clone(),
                         }
                         .into());
                     }
-                    Dependencies::Known(constraints) => constraints,
+                    Dependencies::Available(constraints) => constraints,
                 };
 
                 // Add that package and version if the dependencies are not problematic.
@@ -588,7 +596,7 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
                     | ResolveError::ConflictingUrls(..)),
                 ) = constraints
                 {
-                    return Ok(Dependencies::Unusable(Some(err.to_string())));
+                    return Ok(Dependencies::Unavailable(uncapitalize(err.to_string())));
                 }
                 let mut constraints = constraints?;
 
@@ -610,10 +618,12 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
                     );
                 }
 
-                Ok(Dependencies::Known(constraints.into()))
+                Ok(Dependencies::Available(constraints.into()))
             }
 
-            PubGrubPackage::Python(_) => Ok(Dependencies::Known(DependencyConstraints::default())),
+            PubGrubPackage::Python(_) => {
+                Ok(Dependencies::Available(DependencyConstraints::default()))
+            }
 
             PubGrubPackage::Package(package_name, extra, url) => {
                 // Wait for the metadata to be available.
@@ -640,7 +650,7 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
                         version.clone(),
                     );
                     constraints.insert(PubGrubPackage::Python(PubGrubPython::Target), version);
-                    return Ok(Dependencies::Known(constraints));
+                    return Ok(Dependencies::Available(constraints));
                 }
 
                 let entry = self.index.distributions.wait(&package_id).await?;
@@ -670,7 +680,7 @@ impl<'a, Provider: ResolverProvider> Resolver<'a, Provider> {
                     );
                 }
 
-                Ok(Dependencies::Known(constraints.into()))
+                Ok(Dependencies::Available(constraints.into()))
             }
         }
     }
@@ -877,8 +887,16 @@ enum Response {
 /// For each [Package] there is a set of versions allowed as a dependency.
 #[derive(Clone)]
 enum Dependencies {
-    /// Package dependencies are not usable
-    Unusable(Option<String>),
+    /// Package dependencies are not available.
+    Unavailable(String),
     /// Container for all available package versions.
-    Known(DependencyConstraints<PubGrubPackage, Range<Version>>),
+    Available(DependencyConstraints<PubGrubPackage, Range<Version>>),
+}
+
+fn uncapitalize<T: AsRef<str>>(string: T) -> String {
+    let mut chars = string.as_ref().chars();
+    match chars.next() {
+        None => String::new(),
+        Some(first) => first.to_lowercase().chain(chars).collect(),
+    }
 }

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

@@ -1516,7 +1516,8 @@ fn conflicting_repeated_url_dependency_version_mismatch() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ root dependencies are unusable: Conflicting URLs for package `werkzeug`:
+          ╰─▶ your requirements cannot be used because there are conflicting URLs for
+              package `werkzeug`:
               - https://files.pythonhosted.org/packages/bd/24/11c3ea5a7e866bf2d97f0501d0b4b1c9bbeade102bb4b588f0d2919a5212/Werkzeug-2.0.1-py3-none-any.whl
               - https://files.pythonhosted.org/packages/ff/1d/960bb4017c68674a1cb099534840f18d3def3ce44aed12b5ed8b78e0153e/Werkzeug-2.0.0-py3-none-any.whl
         "###);
@@ -1556,7 +1557,8 @@ fn conflicting_repeated_url_dependency_version_match() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ root dependencies are unusable: Conflicting URLs for package `werkzeug`:
+          ╰─▶ your requirements cannot be used because there are conflicting URLs for
+              package `werkzeug`:
               - git+https://github.com/pallets/werkzeug.git@2.0.0
               - https://files.pythonhosted.org/packages/ff/1d/960bb4017c68674a1cb099534840f18d3def3ce44aed12b5ed8b78e0153e/Werkzeug-2.0.0-py3-none-any.whl
         "###);
@@ -1900,8 +1902,8 @@ dependencies = ["django==5.0b1", "django==5.0a1"]
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ my-project dependencies are unusable: Conflicting versions for `django`:
-              `django==5.0b1` does not intersect with `django==5.0a1`
+          ╰─▶ my-project cannot be used because there are conflicting versions for
+              `django`: `django==5.0b1` does not intersect with `django==5.0a1`
         "###);
     });
 

crates/puffin/tests/pip_compile.rs

@@ -1245,7 +1245,7 @@ fn direct_incompatible_versions() -> Result<()> {
 
         ----- stderr -----
           × No solution found when resolving dependencies:
-          ╰─▶ root dependencies are unusable: Conflicting versions for `albatross`: `albatross==1.0.0` does not intersect with `albatross==2.0.0`
+          ╰─▶ your requirements cannot be used because there are conflicting versions for `albatross`: `albatross==1.0.0` does not intersect with `albatross==2.0.0`
         "###);
     });