Type or namespace not found in package only

I've written an Editor script that uses the LibGit2Sharp library. Downloading the lib and the native code dependency from the web and placing it in Assets/Plugins resulted in the familiar error

The type or namespace name `LibGit2Sharp' could not be found. Are you missing an assembly reference?

I was able to get rid of the missing type/namespace errors by installing LibGit2Sharp in Visual Studio through nuget, then moving the downloaded folders into Assets/Plugins from there. I've now made a Unity package that includes the Editor script and the Plugins folder with all contents. After importing that package into another project I am once again unable to build because of the missing reference error. How can I fix this without downloading through nuget?

Here is the script where I use LibGit2Sharp

Code (CSharp):

1. #if UNITY_EDITOR
2.  
3. using UnityEngine;
4. using UnityEditor;                  // For BuildTarget
5. using UnityEditor.Callbacks;        // For PostProcessBuild
6. using System.IO;                    // For Directory, DirectoryInfo
7. using System;                       // For Exception, DateTime, SystemInfo, String
8. using System.Collections.Generic;   // For List
9. using LibGit2Sharp;                 // For Git repository interaction
10.  
11. public class VersionInfoWriter : MonoBehaviour {
12.  
13.     private static void WriteVersionFile(string path)
14.     {
15.         List<string> versionTextLines = GenerateVersionInfo();
16.  
17.         using (StreamWriter writer = new StreamWriter(path, false))
18.         {
19.             foreach (string line in versionTextLines)
20.             {
21.                 writer.WriteLine(line);
22.             }
23.             writer.Close();
24.         }
25.     }
26.  
27.     private static List<String> GenerateVersionInfo () {
28.  
29.         // For storing version info to write
30.         List<String> versionInfo = new List<string>();
31.  
32.         // Add our own build number from Project Setting in the Unity Editor
33.         versionInfo.Add("Application Version: " + Application.version);
34.         // Time of build and name of computer it was built on
35.         versionInfo.Add("Built at: " + DateTime.Now);
36.         versionInfo.Add("On Computer: " + SystemInfo.deviceName);
37.  
38.         // See if project is in a Git repository
39.         Repository repo = FindRepository();
40.  
41.         // If we are in a repo, get the commit info
42.         // and add it to the versionInfo list
43.         if (repo != null)
44.         {
45.             try
46.             {
47.                 // Add info from the Git repository
48.                 versionInfo.Add("Git Commit SHA: " + repo.Head.Tip.Sha);
49.                 versionInfo.Add("Git Branch Name: " + repo.Head.CanonicalName);
50.             }
51.             catch (Exception e)
52.             {
53.                 Debug.Log(e.ToString());
54.             }
55.         }
56.         else
57.         {
58.             Debug.Log("No repository found.");
59.         }
60.  
61.         return versionInfo;
62.  
63.     }
64.  
65.     private static Repository FindRepository()
66.     {
67.         // get path to project folder
68.         DirectoryInfo dir = Directory.GetParent(Application.dataPath);
69.  
70.         // Recursively check project parent folders
71.         // to see if we are inside a repository
72.         while (!Repository.IsValid(dir.FullName))
73.         {
74.             // We are not at the repository level yet
75.             // switch to parent
76.             dir = dir.Parent;
77.             // If dir is null we reached root directory
78.             // we are not inside a repository
79.             if (dir == null)
80.                 return null;
81.         }
82.         // Return repo directory
83.         return new Repository(dir.FullName);
84.     }
85.  
86.  
87.     // Invoked by the Unity Editor just after building.
88.     // Generate the version info and write it to a text
89.     // file in the build directory.
90.     [PostProcessBuild]
91.     public static void OnPostprocessBuild(BuildTarget target, string pathToBuild)
92.     {
93.         Debug.Log("Creatinig version file in build folder.");
94.  
95.         int lastSlash = pathToBuild.LastIndexOf('/');
96.         pathToBuild = (lastSlash > -1) ? pathToBuild.Substring(0, lastSlash) : pathToBuild;
97.  
98.         WriteVersionFile(pathToBuild + "/version-info.txt");
99.     }
100.  
101. }
102.  
103. #endif

 

I've learned that LibGit2Sharp requires scripting runtime 4.x. I was testing my package in a new project with runtime set to 3.5.

I'll need to notify the users of the package about this in the readme. There isn't a value for runtime version in the package manifest, but I can add it to the description field there as well.