Add package_path to ResolveError

More useful than just the parent

Author: alexheretic

src/cargo/core/resolver/mod.rs

@@ -826,9 +826,18 @@ fn activation_error(
     candidates: &[Candidate],
     config: Option<&Config>,
 ) -> ResolveError {
-    let to_resolve_err = |err| ResolveError::new(err, parent.package_id().clone());
-
     let graph = cx.graph();
+    let to_resolve_err = |err| {
+        ResolveError::new(
+            err,
+            graph
+                .path_to_top(parent.package_id())
+                .into_iter()
+                .cloned()
+                .collect(),
+        )
+    };
+
     if !candidates.is_empty() {
         let mut msg = format!("failed to select a version for `{}`.", dep.package_name());
         msg.push_str("\n    ... required by ");

src/cargo/util/errors.rs

@@ -135,26 +135,26 @@ impl<'a> Iterator for ManifestCauses<'a> {
 
 impl<'a> ::std::iter::FusedIterator for ManifestCauses<'a> {}
 
-/// Error during resolution providing the `PackageId` for the package 
-/// whose requirements could not be resolved.
+/// Error during resolution providing a path of `PackageId`s.
 ///
 /// This error adds no displayable info of it's own.
 pub struct ResolveError {
     cause: Error,
-    parent_package: PackageId,
+    package_path: Vec<PackageId>,
 }
 
 impl ResolveError {
-    pub fn new<E: Into<Error>>(cause: E, parent_package: PackageId) -> Self {
+    pub fn new<E: Into<Error>>(cause: E, package_path: Vec<PackageId>) -> Self {
         Self {
             cause: cause.into(),
-            parent_package,
+            package_path,
         }
     }
 
-    /// Returns the id of the package whose requirements could not be resolved.
-    pub fn parent_package_id(&self) -> &PackageId {
-        &self.parent_package
+    /// Returns a path of packages from the package whose requirements could not be resolved up to
+    /// the root.
+    pub fn package_path(&self) -> &[PackageId] {
+        &self.package_path
     }
 }
 

tests/testsuite/member_errors.rs

@@ -150,5 +150,7 @@ fn member_manifest_version_error() {
     eprintln!("{:?}", error);
 
     let resolve_err: &ResolveError = error.downcast_ref().expect("Not a ResolveError");
-    assert_eq!(resolve_err.parent_package_id(), member_bar.package_id());
+    let package_path = resolve_err.package_path();
+    assert_eq!(package_path.len(), 1, "package_path: {:?}", package_path);
+    assert_eq!(&package_path[0], member_bar.package_id());
 }