当方法具有泛型约束时，前提条件不会被继承 [英] Preconditions not being inherited when method has a generic constraint

问题描述

看起来仍有一些合同未被继承的情况。在这种情况下，overriden方法失去了它的非null前提条件。

这个repro给出1个警告，但是不应该给出任何一个：

Looks like there are still some cases where contracts are not being inherited. In this case an overriden method loses its non-null precondition.

This repro gives 1 warning, but should give none:

<ContractClass(GetType(B(Of ).ContractClass))>
MustInherit Class B(Of T)
    MustOverride Sub S(Of R As T)(ByVal arg As R)

    <ContractClassFor(GetType(B(Of )))>
    MustInherit Class ContractClass
        Inherits B(Of T)
        Overrides Sub S(Of R As T)(ByVal arg As R)
            Contract.Requires(arg IsNot Nothing)
        End Sub
    End Class
End Class

Class C
    Inherits B(Of IList(Of Byte))
    Overrides Sub S(Of R As IList(Of Byte))(ByVal arg As R)
        Contract.Assert(arg IsNot Nothing)
    End Sub
End Class

推荐答案

请不要将契约类嵌套在另一个类中。目前，合同和相应的接口/抽象类应该是结构中的兄弟姐妹。我可以看出为什么它适用于非泛型类型，但它绝对是泛型的问题。

Please don't put the contract class nested inside another class. At the moment, the contract and corresponding interface/abstract class should be siblings in the structure. I can see why it works for non-generic types, but it is definitely a problem with generics.

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