C# 代码契约-静态检查器不'；无法获取可为空的类型？

我想我在静态契约检查工具中发现了一个bug。除了用

[ContractVerification（false）]

标记整个项目外，还有其他方法吗

class Employee
{
    public int? HierarchyLevel { get; private set; }

    public Employee(int? level)
    {
        Contract.Requires<ArgumentException>(
            (!level.HasValue) 
            || 
            level >= 0 && level <= 10);
        Contract.Ensures(
            (!HierarchyLevel.HasValue) 
            || 
            (HierarchyLevel.Value >= 0 && HierarchyLevel.Value <= 10));
        this.HierarchyLevel = level; //unproven

        // this doesnt work either
        //if (!level.HasValue) {
        //    this.HierarchyLevel = new Nullable<int>();
        //} else {
        //    this.HierarchyLevel = new Nullable<int>(level.Value);
        //}

        // can't even make the static checker shut up with that:
        //Contract.Assume(
        //    (!HierarchyLevel.HasValue) 
        //    || 
        //    (HierarchyLevel.Value >= 0 && HierarchyLevel.Value <= 10));
    }
}

class员工
{
public int？HierarchyLevel{get；private set；}
公共雇员（国际级）
{
合同。需要(
（！level.HasValue）
|| 
level>=0&&level=0&&HierarchyLevel.Value=0&&level=0&&HierarchyLevel首先，您在代码中放错了一些大括号（但这并不能解决您的问题）：

class Employee2
{
    public int HierarchyLevel { get; private set; }
    public bool HasLevel { get; private set; }
    public Employee2(int level, bool hasLevel)
    {
        Contract.Requires<ArgumentException>(!hasLevel || level >= 0 && level <=10);
        if (hasLevel) {
            HasLevel = true;
            HierarchyLevel = level;
        } else {
            HasLevel = false;
            HierarchyLevel = -1;
        }
    }
    [ContractInvariantMethod]
    private void ObjectInvariant()
    {
        Contract.Invariant(
            (!HasLevel) || 
            (HierarchyLevel >= 0 && HierarchyLevel <= 10));
    }
}

Contract.Requires<ArgumentException>(!level.HasValue
    || (level.Value >= 0 && level.Value <= 10));
Contract.Ensures(!HierarchyLevel.HasValue
    || (HierarchyLevel.Value >= 0 && HierarchyLevel.Value <= 10));

Contract.Requires<ArgumentException>(!level.HasValue
    || (level.Value >= 0 && level.Value <= 10);
Contract.Ensures(HierarchyLevel == level);

[Pure]
public static bool IsInRange(int? value)
{
    return !value.HasValue
        || (value >= 0 && value <= 10);
}

public Employee(int? level)
{
    Contract.Requires<ArgumentException>(IsInRange(level));
    Contract.Ensures(IsInRange(HierarchyLevel));
    this.HierarchyLevel = level;
}