Error Reporting (swiftlang#2066)

* Fix wrong cause for root dependencies * Remove temporary error output * Move error reporting into DiagnosticReportBuilder * CustomStringConvertible PackageRequirement * Ignore additional whitespace in AssertUnresolvable * Assert root cause diagnostics * skip diagnostic in testMissingVersion

Author: kiliankoe

Sources/PackageGraph/DependencyResolver.swift

@@ -258,6 +258,16 @@ public enum PackageRequirement: Hashable {
  }
 }
 
+extension PackageRequirement: CustomStringConvertible {
+ public var description: String {
+ switch self {
+ case .versionSet(let versionSet): return versionSet.description
+ case .revision(let revision): return revision
+ case .unversioned: return "unversioned"
+ }
+ }
+}
+
 /// A container of packages.
 ///
 /// This is the top-level unit of package resolution, i.e. the unit at which