.net System.IO.Directory.Exists 在 LINQ 语句中失败，但在 foreach 循环中没有

.Net Framework 4.7.2

这是一个非常令人惊讶的问题...

我有一个 routine ，可以从本地磁盘获取所有可用的Inventor模板，无论它是哪个版本:

private static IEnumerable<string> GetInventorTemplates_FAILS()
{
    var publicPath = Environment.GetEnvironmentVariable("PUBLIC");
    var autodeskPath = Path.Combine(publicPath, "Documents", "Autodesk");
    var inventorPaths = Directory.GetDirectories(autodeskPath, "*Inventor*");
    var templatePaths = inventorPaths.Select(path => Path.Combine(path, "Templates"));
    var templates = templatePaths.Where(Directory.Exists).SelectMany(path => Directory.GetFiles(path, "*.*", SearchOption.AllDirectories));
    //                     throws error ^^^^^^^^^^^^^^^^

    return templates;
}

如果我运行此代码，我会出现以下错误:

System.Linq.SystemCore_EnumerableDebugView`1[System.String].get_Items() calls into native method Microsoft.Win32.Win32Native.GetFullPathName(char*, int, char*, System.IntPtr). Evaluation of native methods in this context is not supported.  

更疯狂的是，如果我重写代码，手动调用Directory.Exists，它就会工作！！！

private static IEnumerable<string> GetInventorTemplates_WORKS()
{
    var publicPath = Environment.GetEnvironmentVariable("PUBLIC");
    var autodeskPath = Path.Combine(publicPath, "Documents", "Autodesk");
    var inventorPaths = Directory.GetDirectories(autodeskPath, "*Inventor*");
    var templatePaths = inventorPaths.Select(path => Path.Combine(path, "Templates"));

    foreach (var path in templatePaths)
        if (Directory.Exists(path)) // <- no exception!!!
            foreach (var template in Directory.GetFiles(path, "*.*", SearchOption.AllDirectories))
                yield return template;
}

如果您只需通过QuickWatch进行判断，就会得到相同的结果:

现在我可以使用重写的版本，但我很好奇我是不是幸运的…:-)