Consolidate UnusableDependencies into a generic Unavailable incom…

…patibility (#20)

* Consolidate `UnusableDependencies` into a generic `Unavailable` incompatibility

* Docs

examples/caching_dependency_provider.rs

@@ -39,18 +39,18 @@ impl<P: Package, VS: VersionSet, DP: DependencyProvider<P, VS>> DependencyProvid
     ) -> Result<Dependencies<P, VS>, DP::Err> {
         let mut cache = self.cached_dependencies.borrow_mut();
         match cache.get_dependencies(package, version) {
-            Ok(Dependencies::Unknown) => {
+            Ok(Dependencies::Unavailable) => {
                 let dependencies = self.remote_dependencies.get_dependencies(package, version);
                 match dependencies {
-                    Ok(Dependencies::Known(dependencies)) => {
+                    Ok(Dependencies::Available(dependencies)) => {
                         cache.add_dependencies(
                             package.clone(),
                             version.clone(),
                             dependencies.clone(),
                         );
-                        Ok(Dependencies::Known(dependencies))
+                        Ok(Dependencies::Available(dependencies))
                     }
-                    Ok(Dependencies::Unknown) => Ok(Dependencies::Unknown),
+                    Ok(Dependencies::Unavailable) => Ok(Dependencies::Unavailable),
                     error @ Err(_) => error,
                 }
             }

examples/unsat_root_message_no_version.rs

@@ -73,18 +73,11 @@ impl ReportFormatter<Package, Range<SemanticVersion>> for CustomReportFormatter
                     format!("there is no version of {package} in {set}")
                 }
             }
-            External::UnavailableDependencies(package, set) => {
+            External::Unavailable(package, set, reason) => {
                 if set == &Range::full() {
-                    format!("dependencies of {package} are unavailable")
+                    format!("dependencies of {package} are unavailable because {reason}")
                 } else {
-                    format!("dependencies of {package} at version {set} are unavailable")
-                }
-            }
-            External::UnusableDependencies(package, set, ..) => {
-                if set == &Range::full() {
-                    format!("dependencies of {package} are unusable")
-                } else {
-                    format!("dependencies of {package} at version {set} are unusable")
+                    format!("dependencies of {package} at version {set} are unavailable because {reason}")
                 }
             }
             External::FromDependencyOf(package, package_set, dependency, dependency_set) => {

src/internal/incompatibility.rs

@@ -45,10 +45,8 @@ pub enum Kind<P: Package, VS: VersionSet> {
     NotRoot(P, VS::V),
     /// There are no versions in the given range for this package.
     NoVersions(P, VS),
-    /// Dependencies of the package are unavailable for versions in that range.
-    UnavailableDependencies(P, VS),
-    /// Dependencies of the package are unusable for versions in that range.
-    UnusableDependencies(P, VS, Option<String>),
+    /// The package is unavailable for versions in the range. A string reason is included.
+    Unavailable(P, VS, String),
     /// Incompatibility coming from the dependencies of a given package.
     FromDependencyOf(P, VS, P, VS),
     /// Derived from two causes. Stores cause ids.
@@ -99,23 +97,11 @@ impl<P: Package, VS: VersionSet> Incompatibility<P, VS> {
 
     /// Create an incompatibility to remember
     /// that a package version is not selectable
-    /// because its list of dependencies is unavailable.
-    pub fn unavailable_dependencies(package: P, version: VS::V) -> Self {
+    pub fn unavailable(package: P, version: VS::V, reason: String) -> Self {
         let set = VS::singleton(version);
         Self {
             package_terms: SmallMap::One([(package.clone(), Term::Positive(set.clone()))]),
-            kind: Kind::UnavailableDependencies(package, set),
-        }
-    }
-
-    /// Create an incompatibility to remember
-    /// that a package version is not selectable
-    /// because its dependencies are not usable.
-    pub fn unusable_dependencies(package: P, version: VS::V, reason: Option<String>) -> Self {
-        let set = VS::singleton(version);
-        Self {
-            package_terms: SmallMap::One([(package.clone(), Term::Positive(set.clone()))]),
-            kind: Kind::UnusableDependencies(package, set, reason),
+            kind: Kind::Unavailable(package, set, reason),
         }
     }
 
@@ -259,11 +245,8 @@ impl<P: Package, VS: VersionSet> Incompatibility<P, VS> {
             Kind::NoVersions(package, set) => {
                 DerivationTree::External(External::NoVersions(package.clone(), set.clone()))
             }
-            Kind::UnavailableDependencies(package, set) => DerivationTree::External(
-                External::UnavailableDependencies(package.clone(), set.clone()),
-            ),
-            Kind::UnusableDependencies(package, set, reason) => DerivationTree::External(
-                External::UnusableDependencies(package.clone(), set.clone(), reason.clone()),
+            Kind::Unavailable(package, set, reason) => DerivationTree::External(
+                External::Unavailable(package.clone(), set.clone(), reason.clone()),
             ),
             Kind::FromDependencyOf(package, set, dep_package, dep_set) => {
                 DerivationTree::External(External::FromDependencyOf(
@@ -339,12 +322,12 @@ pub mod tests {
             let mut store = Arena::new();
             let i1 = store.alloc(Incompatibility {
                 package_terms: SmallMap::Two([("p1", t1.clone()), ("p2", t2.negate())]),
-                kind: Kind::UnavailableDependencies("0", Range::full())
+                kind: Kind::Unavailable("0", Range::full(), "foo".to_string())
             });
 
             let i2 = store.alloc(Incompatibility {
                 package_terms: SmallMap::Two([("p2", t2), ("p3", t3.clone())]),
-                kind: Kind::UnavailableDependencies("0", Range::full())
+                kind: Kind::Unavailable("0", Range::full(), "bar".to_string())
             });
 
             let mut i3 = Map::default();

src/report.rs

@@ -48,10 +48,8 @@ pub enum External<P: Package, VS: VersionSet> {
     NotRoot(P, VS::V),
     /// There are no versions in the given set for this package.
     NoVersions(P, VS),
-    /// Dependencies of the package are unavailable for versions in that set.
-    UnavailableDependencies(P, VS),
-    /// Dependencies of the package are unusable for versions in that set.
-    UnusableDependencies(P, VS, Option<String>),
+    /// The package is unusable in the given set. A string reason is included.
+    Unavailable(P, VS, String),
     /// Incompatibility coming from the dependencies of a given package.
     FromDependencyOf(P, VS, P, VS),
 }
@@ -85,8 +83,7 @@ impl<P: Package, VS: VersionSet> DerivationTree<P, VS> {
                 }
                 External::NoVersions(p, _)
                 | External::NotRoot(p, _)
-                | External::UnavailableDependencies(p, _)
-                | External::UnusableDependencies(p, ..) => {
+                | External::Unavailable(p, ..) => {
                     packages.insert(p);
                 }
             },
@@ -146,16 +143,8 @@ impl<P: Package, VS: VersionSet> DerivationTree<P, VS> {
             DerivationTree::External(External::NoVersions(_, r)) => Some(DerivationTree::External(
                 External::NoVersions(package, set.union(&r)),
             )),
-            DerivationTree::External(External::UnavailableDependencies(_, r)) => Some(
-                DerivationTree::External(External::UnavailableDependencies(package, set.union(&r))),
-            ),
-            DerivationTree::External(External::UnusableDependencies(_, r, reason)) => {
-                Some(DerivationTree::External(External::UnusableDependencies(
-                    package,
-                    set.union(&r),
-                    reason,
-                )))
-            }
+            // Cannot be merged because the reason may not match
+            DerivationTree::External(External::Unavailable(_, _, _)) => None,
             DerivationTree::External(External::FromDependencyOf(p1, r1, p2, r2)) => {
                 if p1 == package {
                     Some(DerivationTree::External(External::FromDependencyOf(
@@ -190,40 +179,21 @@ impl<P: Package, VS: VersionSet> fmt::Display for External<P, VS> {
                     write!(f, "there is no version of {} in {}", package, set)
                 }
             }
-            Self::UnavailableDependencies(package, set) => {
+            Self::Unavailable(package, set, reason) => {
                 if set == &VS::full() {
-                    write!(f, "dependencies of {} are unavailable", package)
+                    write!(
+                        f,
+                        "dependencies of {} are unavailable because {reason}",
+                        package
+                    )
                 } else {
                     write!(
                         f,
-                        "dependencies of {} at version {} are unavailable",
+                        "dependencies of {} at version {} are unavailable because {reason}",
                         package, set
                     )
                 }
             }
-            Self::UnusableDependencies(package, set, reason) => {
-                if let Some(reason) = reason {
-                    if set == &VS::full() {
-                        write!(f, "dependencies of {} are unusable: {reason}", package)
-                    } else {
-                        write!(
-                            f,
-                            "dependencies of {} at version {} are unusable: {reason}",
-                            package, set
-                        )
-                    }
-                } else {
-                    if set == &VS::full() {
-                        write!(f, "dependencies of {} are unusable", package)
-                    } else {
-                        write!(
-                            f,
-                            "dependencies of {} at version {} are unusable",
-                            package, set
-                        )
-                    }
-                }
-            }
             Self::FromDependencyOf(p, set_p, dep, set_dep) => {
                 if set_p == &VS::full() && set_dep == &VS::full() {
                     write!(f, "{} depends on {}", p, dep)

src/solver.rs

@@ -158,20 +158,21 @@ pub fn resolve<P: Package, VS: VersionSet, DP: DependencyProvider<P, VS>>(
             })?;
 
             let known_dependencies = match dependencies {
-                Dependencies::Unknown => {
-                    state.add_incompatibility(Incompatibility::unavailable_dependencies(
+                Dependencies::Unavailable => {
+                    state.add_incompatibility(Incompatibility::unavailable(
                         p.clone(),
                         v.clone(),
+                        "its dependencies could not be determined".to_string(),
                     ));
                     continue;
                 }
-                Dependencies::Known(x) if x.contains_key(p) => {
+                Dependencies::Available(x) if x.contains_key(p) => {
                     return Err(PubGrubError::SelfDependency {
                         package: p.clone(),
                         version: v,
                     });
                 }
-                Dependencies::Known(x) => x,
+                Dependencies::Available(x) => x,
             };
 
             // Add that package and version if the dependencies are not problematic.
@@ -201,9 +202,9 @@ pub fn resolve<P: Package, VS: VersionSet, DP: DependencyProvider<P, VS>>(
 #[derive(Clone)]
 pub enum Dependencies<P: Package, VS: VersionSet> {
     /// Package dependencies are unavailable.
-    Unknown,
+    Unavailable,
     /// Container for all available package versions.
-    Known(DependencyConstraints<P, VS>),
+    Available(DependencyConstraints<P, VS>),
 }
 
 /// Trait that allows the algorithm to retrieve available packages and their dependencies.
@@ -254,7 +255,7 @@ pub trait DependencyProvider<P: Package, VS: VersionSet> {
     fn choose_version(&self, package: &P, range: &VS) -> Result<Option<VS::V>, Self::Err>;
 
     /// Retrieves the package dependencies.
-    /// Return [Dependencies::Unknown] if its dependencies are unknown.
+    /// Return [Dependencies::Unavailable] if its dependencies are not available.
     fn get_dependencies(
         &self,
         package: &P,
@@ -369,8 +370,8 @@ impl<P: Package, VS: VersionSet> DependencyProvider<P, VS> for OfflineDependency
         version: &VS::V,
     ) -> Result<Dependencies<P, VS>, Infallible> {
         Ok(match self.dependencies(package, version) {
-            None => Dependencies::Unknown,
-            Some(dependencies) => Dependencies::Known(dependencies),
+            None => Dependencies::Unavailable,
+            Some(dependencies) => Dependencies::Available(dependencies),
         })
     }
 }

src/type_aliases.rs

@@ -11,7 +11,7 @@ pub type SelectedDependencies<P, V> = Map<P, V>;
 
 /// Holds information about all possible versions a given package can accept.
 /// There is a difference in semantics between an empty map
-/// inside [DependencyConstraints] and [Dependencies::Unknown](crate::solver::Dependencies::Unknown):
+/// inside [DependencyConstraints] and [Dependencies::Unavailable](crate::solver::Dependencies::Unavailable):
 /// the former means the package has no dependency and it is a known fact,
 /// while the latter means they could not be fetched by the [DependencyProvider](crate::solver::DependencyProvider).
 pub type DependencyConstraints<P, VS> = Map<P, VS>;

tests/proptest.rs

@@ -309,8 +309,8 @@ fn retain_versions<N: Package + Ord, VS: VersionSet>(
                 continue;
             }
             let deps = match dependency_provider.get_dependencies(n, v).unwrap() {
-                Dependencies::Unknown => panic!(),
-                Dependencies::Known(deps) => deps,
+                Dependencies::Unavailable => panic!(),
+                Dependencies::Available(deps) => deps,
             };
             smaller_dependency_provider.add_dependencies(n.clone(), v.clone(), deps)
         }
@@ -333,8 +333,8 @@ fn retain_dependencies<N: Package + Ord, VS: VersionSet>(
     for n in dependency_provider.packages() {
         for v in dependency_provider.versions(n).unwrap() {
             let deps = match dependency_provider.get_dependencies(n, v).unwrap() {
-                Dependencies::Unknown => panic!(),
-                Dependencies::Known(deps) => deps,
+                Dependencies::Unavailable => panic!(),
+                Dependencies::Available(deps) => deps,
             };
             smaller_dependency_provider.add_dependencies(
                 n.clone(),
@@ -504,8 +504,8 @@ proptest! {
                 .get_dependencies(package, version)
                 .unwrap()
             {
-                Dependencies::Unknown => panic!(),
-                Dependencies::Known(d) => d.into_iter().collect(),
+                Dependencies::Unavailable => panic!(),
+                Dependencies::Available(d) => d.into_iter().collect(),
             };
             if !dependencies.is_empty() {
                 to_remove.insert((package, **version, dep_idx.get(&dependencies).0));

tests/sat_dependency_provider.rs

@@ -68,8 +68,8 @@ impl<P: Package, VS: VersionSet> SatResolve<P, VS> {
         // active packages need each of there `deps` to be satisfied
         for (p, v, var) in &all_versions {
             let deps = match dp.get_dependencies(p, v).unwrap() {
-                Dependencies::Unknown => panic!(),
-                Dependencies::Known(d) => d,
+                Dependencies::Unavailable => panic!(),
+                Dependencies::Available(d) => d,
             };
             for (p1, range) in &deps {
                 let empty_vec = vec![];