From 910e5d977c49d1cc479d0e0d2784a0a268bc8361 Mon Sep 17 00:00:00 2001
From: Zanie Blue <contact@zanie.dev>
Date: Mon, 5 Feb 2024 08:36:10 -0600
Subject: [PATCH] Add a `reason` to the `NoVersions` incompatibility (#22)

---
 examples/unsat_root_message_no_version.rs |  2 +-
 src/internal/incompatibility.rs           |  6 ++----
 src/report.rs                             | 13 ++++++-------
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/examples/unsat_root_message_no_version.rs b/examples/unsat_root_message_no_version.rs
index 8b01bcf1..5b52358f 100644
--- a/examples/unsat_root_message_no_version.rs
+++ b/examples/unsat_root_message_no_version.rs
@@ -71,7 +71,7 @@ impl ReportFormatter<Package, Range<SemanticVersion>, String> for CustomReportFo
             External::NotRoot(package, version) => {
                 format!("we are solving dependencies of {package} {version}")
             }
-            External::NoVersions(package, set) => {
+            External::NoVersions(package, set, _) => {
                 if set == &Range::full() {
                     format!("there is no available version for {package}")
                 } else {
diff --git a/src/internal/incompatibility.rs b/src/internal/incompatibility.rs
index 4288a676..fb45ca48 100644
--- a/src/internal/incompatibility.rs
+++ b/src/internal/incompatibility.rs
@@ -354,12 +354,10 @@ impl<P: Package, VS: VersionSet, M: Eq + Clone + Debug + Display> fmt::Display
 
 #[cfg(test)]
 pub mod tests {
-    use proptest::prelude::*;
-
+    use super::*;
     use crate::range::Range;
     use crate::term::tests::strategy as term_strat;
-
-    use super::*;
+    use proptest::prelude::*;
 
     proptest! {
 
diff --git a/src/report.rs b/src/report.rs
index b3d761a6..82eddaac 100644
--- a/src/report.rs
+++ b/src/report.rs
@@ -45,8 +45,8 @@ pub enum DerivationTree<P: Package, VS: VersionSet, M: Eq + Clone + Debug + Disp
 pub enum External<P: Package, VS: VersionSet, M: Eq + Clone + Debug + Display> {
     /// Initial incompatibility aiming at picking the root package for the first decision.
     NotRoot(P, VS::V),
-    /// There are no versions in the given set for this package.
-    NoVersions(P, VS),
+    /// There are no versions in the given set for this package. A string reason is included.
+    NoVersions(P, VS, Option<String>),
     /// Incompatibility coming from the dependencies of a given package.
     FromDependencyOf(P, VS, P, VS),
     /// The package is unusable for reasons outside pubgrub.
@@ -80,7 +80,7 @@ impl<P: Package, VS: VersionSet, M: Eq + Clone + Debug + Display> DerivationTree
                     packages.insert(p);
                     packages.insert(p2);
                 }
-                External::NoVersions(p, _)
+                External::NoVersions(p, _, _)
                 | External::NotRoot(p, _)
                 | External::Custom(p, _, _) => {
                     packages.insert(p);
@@ -113,14 +113,14 @@ impl<P: Package, VS: VersionSet, M: Eq + Clone + Debug + Display> DerivationTree
                     Arc::make_mut(&mut derived.cause1),
                     Arc::make_mut(&mut derived.cause2),
                 ) {
-                    (DerivationTree::External(External::NoVersions(p, r)), ref mut cause2) => {
+                    (DerivationTree::External(External::NoVersions(p, r, _)), ref mut cause2) => {
                         cause2.collapse_no_versions();
                         *self = cause2
                             .clone()
                             .merge_no_versions(p.to_owned(), r.to_owned())
                             .unwrap_or_else(|| self.to_owned());
                     }
-                    (ref mut cause1, DerivationTree::External(External::NoVersions(p, r))) => {
+                    (ref mut cause1, DerivationTree::External(External::NoVersions(p, r, _))) => {
                         cause1.collapse_no_versions();
                         *self = cause1
                             .clone()
@@ -144,7 +144,6 @@ impl<P: Package, VS: VersionSet, M: Eq + Clone + Debug + Display> DerivationTree
             DerivationTree::External(External::NotRoot(_, _)) => {
                 panic!("How did we end up with a NoVersions merged with a NotRoot?")
             }
-            //
             // Cannot be merged because the reason may not match
             DerivationTree::External(External::NoVersions(_, _)) => None,
             DerivationTree::External(External::Custom(_, r, reason)) => Some(
@@ -179,7 +178,7 @@ impl<P: Package, VS: VersionSet, M: Eq + Clone + Debug + Display> fmt::Display
             Self::NotRoot(package, version) => {
                 write!(f, "we are solving dependencies of {} {}", package, version)
             }
-            Self::NoVersions(package, set) => {
+            Self::NoVersions(package, set, _) => {
                 if set == &VS::full() {
                     write!(f, "there is no available version for {}", package)
                 } else {