Backjump on a source or description mismatch.

sdk/lib/_internal/pub/lib/src/solver/version_solver.dart

Index: sdk/lib/_internal/pub/lib/src/solver/version_solver.dart
diff --git a/sdk/lib/_internal/pub/lib/src/solver/version_solver.dart b/sdk/lib/_internal/pub/lib/src/solver/version_solver.dart
index efd9e85ce5b9939040ee8a56d56d8764e6cd42fc..823b0d3688104aa83217136fd0b5c4ae01288a61 100644
--- a/sdk/lib/_internal/pub/lib/src/solver/version_solver.dart
+++ b/sdk/lib/_internal/pub/lib/src/solver/version_solver.dart
@@ -162,6 +162,12 @@ class SolveFailure implements Exception {
   /// an empty collection if the failure is not specific to one package.
   final Iterable<Dependency> dependencies;
 
+  /// If this is `true`, then it may be possible to avoid this failure by
+  /// adjusting one of the transitive dependencies of a package in
+  /// [dependencies]. Otherwise, [dependencies] themselves are in conflict and
+  /// only changing one of those may resolve the failure.
+  bool get mayHaveTransitiveCause => true;
+
   SolveFailure(this.package, Iterable<Dependency> dependencies)
       : dependencies = dependencies != null ? dependencies : <Dependency>[];
 
@@ -275,6 +281,8 @@ class SourceMismatchException extends SolveFailure {
   SourceMismatchException(String package, Iterable<Dependency> dependencies)
       : super(package, dependencies);
 
+  bool get mayHaveTransitiveCause => false;
+
   String get _message => "Incompatible dependencies on '$package'";
 
   String _describeDependency(PackageDep dep) =>
@@ -288,6 +296,8 @@ class DescriptionMismatchException extends SolveFailure {
       Iterable<Dependency> dependencies)
       : super(package, dependencies);
 
+  bool get mayHaveTransitiveCause => false;
+
   String get _message => "Incompatible dependencies on '$package'";
 
   String _describeDependency(PackageDep dep) {