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Add support for variance safety for static interface members #1343

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8 changes: 4 additions & 4 deletions standard/interfaces.md
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Expand Up @@ -91,21 +91,21 @@ If a generic interface is declared in multiple parts ([§15.2.3](classes.md#1523

#### 18.2.3.2 Variance safety

The occurrence of variance annotations in the type parameter list of a type restricts the places where types can occur within the type declaration.
The occurrence of variance annotations in the type parameter list of a type restricts the places where types can occur within the type declaration. However, these restrictions do not apply to occurrences of types within a declaration of a static member.

A type T is ***output-unsafe*** if one of the following holds:
A type `T` is ***output-unsafe*** if one of the following holds:

- `T` is a contravariant type parameter
- `T` is an array type with an output-unsafe element type
- `T` is an interface or delegate type `Sᵢ,... Aₑ` constructed from a generic type `S<Xᵢ, ... Xₑ>` where for at least one `Aᵢ` one of the following holds:
- `Xᵢ` is covariant or invariant and `Aᵢ` is output-unsafe.
- `Xᵢ` is contravariant or invariant and `Aᵢ` is input-unsafe.

A type T is ***input-unsafe*** if one of the following holds:
A type `T` is ***input-unsafe*** if one of the following holds:

- `T` is a covariant type parameter
- `T` is an array type with an input-unsafe element type
- `T` is an interface or delegate type `S<Aᵢ,... Aₑ>` constructed from a generic type `S<Xᵢ, ... Xₑ>` where for at least one `Aᵢ` one of the following holds:
- `T` is an interface or delegate type `S<Aᵢ,... Aₑ>` constructed from a generic type `S<Xᵢ, ... Xₑ>` where for at least one `Aᵢ` one of the following holds:
- `Xᵢ` is covariant or invariant and `Aᵢ` is input-unsafe.
- `Xᵢ` is contravariant or invariant and `Aᵢ` is output-unsafe.

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