Package.computeDefaultName: support the Windows path separator

Author: troughton

Sources/PackageModel/Package.swift

@@ -138,7 +138,16 @@ public struct PackageReference: JSONMappable, JSONSerializable, Codable, CustomS
     /// Compute the default name of a package given its URL.
     public static func computeDefaultName(fromURL url: String) -> String {
         // Get the last path component of the URL.
-        var lastComponent = url.split(separator: "/", omittingEmptySubsequences: true).last ?? url[...]
+     
+      #if os(Windows)
+        let isSeparator : (Character) -> Bool = { $0 == "/" || $0 == "\\" }
+      #else
+        let isSeparator : (Character) -> Bool = { $0 == "/" }
+      #endif
+        let separatorIndex = url.lastIndex(where: isSeparator)
+        let startIndex = separatorIndex.map { url.index(after: $0) } ?? url.startIndex
+
+        var lastComponent = url[startIndex...]
 
         // Strip `.git` suffix if present.
         if lastComponent.hasSuffix(".git") {