Use a custom PubGrub error type to always show resolution report (#365)

Closes https://github.com/astral-sh/puffin/issues/356.

The example from the issue now renders as:

```
❯ cargo run --bin puffin-dev -q -- resolve-cli tensorflow-cpu-aws
puffin-dev failed
  Caused by: No solution found when resolving build dependencies for source distribution:
  Caused by: Because there is no available version for tensorflow-cpu-aws and root depends on tensorflow-cpu-aws, version solving failed.
```

crates/puffin-cli/src/commands/pip_compile.rs

@@ -7,7 +7,7 @@ use anyhow::{anyhow, Result};
 use colored::Colorize;
 use fs_err::File;
 use itertools::Itertools;
-use pubgrub::report::Reporter;
+
 use tracing::debug;
 
 use pep508_rs::Requirement;
@@ -17,7 +17,7 @@ use puffin_client::RegistryClientBuilder;
 use puffin_dispatch::BuildDispatch;
 use puffin_interpreter::Virtualenv;
 use puffin_normalize::ExtraName;
-use puffin_resolver::{Manifest, PreReleaseMode, ResolutionFailureReporter, ResolutionMode};
+use puffin_resolver::{Manifest, PreReleaseMode, ResolutionMode};
 use std::str::FromStr;
 
 use crate::commands::reporters::ResolverReporter;
@@ -149,14 +149,11 @@ pub(crate) async fn pip_compile(
     )
     .with_reporter(ResolverReporter::from(printer));
     let resolution = match resolver.resolve().await {
-        Err(puffin_resolver::ResolveError::PubGrub(pubgrub::error::PubGrubError::NoSolution(
-            derivation_tree,
-        ))) => {
+        Err(puffin_resolver::ResolveError::PubGrub(err)) => {
             #[allow(clippy::print_stderr)]
             {
-                let report =
-                    miette::Report::msg(ResolutionFailureReporter::report(&derivation_tree))
-                        .context("No solution found when resolving dependencies:");
+                let report = miette::Report::msg(format!("{err}"))
+                    .context("No solution found when resolving dependencies:");
                 eprint!("{report:?}");
             }
             return Ok(ExitStatus::Failure);

crates/puffin-dispatch/src/lib.rs

@@ -85,7 +85,7 @@ impl BuildContext for BuildDispatch {
                 self,
             );
             let resolution_graph = resolver.resolve().await.context(
-                "No solution found when resolving build dependencies for source distribution build",
+                "No solution found when resolving build dependencies for source distribution:",
             )?;
             Ok(resolution_graph.requirements())
         })

crates/puffin-resolver/src/error.rs

@@ -1,4 +1,7 @@
+use std::fmt::Formatter;
+
 use pubgrub::range::Range;
+use pubgrub::report::Reporter;
 use thiserror::Error;
 use url::Url;
 
@@ -6,6 +9,7 @@ use pep508_rs::Requirement;
 use puffin_normalize::PackageName;
 
 use crate::pubgrub::{PubGrubPackage, PubGrubVersion};
+use crate::ResolutionFailureReporter;
 
 #[derive(Error, Debug)]
 pub enum ResolveError {
@@ -25,7 +29,7 @@ pub enum ResolveError {
     Join(#[from] tokio::task::JoinError),
 
     #[error(transparent)]
-    PubGrub(#[from] pubgrub::error::PubGrubError<PubGrubPackage, Range<PubGrubVersion>>),
+    PubGrub(#[from] RichPubGrubError),
 
     #[error("Package metadata name `{metadata}` does not match given name `{given}`")]
     NameMismatch {
@@ -64,3 +68,28 @@ impl<T> From<futures::channel::mpsc::TrySendError<T>> for ResolveError {
         value.into_send_error().into()
     }
 }
+
+/// A wrapper around [`pubgrub::error::PubGrubError`] that displays a resolution failure report.
+#[derive(Debug)]
+pub struct RichPubGrubError {
+    source: pubgrub::error::PubGrubError<PubGrubPackage, Range<PubGrubVersion>>,
+}
+
+impl std::error::Error for RichPubGrubError {}
+
+impl std::fmt::Display for RichPubGrubError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        if let pubgrub::error::PubGrubError::NoSolution(derivation_tree) = &self.source {
+            let report = ResolutionFailureReporter::report(derivation_tree);
+            write!(f, "{report}")
+        } else {
+            write!(f, "{}", self.source)
+        }
+    }
+}
+
+impl From<pubgrub::error::PubGrubError<PubGrubPackage, Range<PubGrubVersion>>> for ResolveError {
+    fn from(value: pubgrub::error::PubGrubError<PubGrubPackage, Range<PubGrubVersion>>) -> Self {
+        ResolveError::PubGrub(RichPubGrubError { source: value })
+    }
+}

crates/puffin-resolver/tests/snapshots/resolver__black_allow_prerelease_if_necessary.snap

@@ -2,4 +2,4 @@
 source: crates/puffin-resolver/tests/resolver.rs
 expression: resolution
 ---
-No solution
+Because there is no version of black available matching <=20.0 and root depends on black<=20.0, version solving failed.

crates/puffin-resolver/tests/snapshots/resolver__black_disallow_prerelease.snap

@@ -2,4 +2,4 @@
 source: crates/puffin-resolver/tests/resolver.rs
 expression: err
 ---
-No solution
+Because there is no version of black available matching <=20.0 and root depends on black<=20.0, version solving failed.