Add doc for CA2260

docs/fundamentals/code-analysis/quality-rules/ca2260.md

@@ -0,0 +1,64 @@
+---
+title: "CA2260: Implement generic math interfaces correctly"
+description: "Learn about code analysis rule CA2260 - Generic math interfaces require the derived type itself to be used for the self recurring type parameter."
+ms.date: 10/06/2022
+ms.topic: reference
+f1_keywords:
+- CA2260
+- ImplementGenericMathInterfacesCorrectly
+helpviewer_keywords:
+- ImplementGenericMathInterfacesCorrectly
+- CA2260
+author: buyaa-n
+---
+# CA2260: Implement generic math interfaces correctly
+
+|                                     | Value                                |
+| ----------------------------------- | ------------------------------------ |
+| **Rule ID**                         | CA2260                               |
+| **Category**                        | [Usage](usage-warnings.md)           |
+| **Fix is breaking or non-breaking** | Non-breaking                         |
+
+## Cause
+
+This rule fires when you implement a generic math interface that requires a self-recurring type parameter and you don't pass the type itself as the type parameter.
+
+## Rule description
+
+Some generic math interfaces introduce static abstract members. The only way to access those static members is through a generic constraint that implements the "curiously recurring template pattern" (CRTP). Therefore, the derived type itself must be used for the self-recurring type parameter. If a type implements such an interface without passing the required type parameter and CA2260 is ignored, the code will compile successfully but the static abstract will not be accessible. Thus, the type will not be usable. The compiler emits a warning with ID CS0315 on such usage.
+
+## How to fix violations
+
+Pass correct type parameter for self recurring type parameter (TSelf) when implementing those interfaces.
+
+### Example
+
+**Violation**:
+
+```csharp
+using System;
+
+// Warns: The 'IParsable<TSelf>' requires the 'TSelf' type parameter to be filled with the derived type 'MyDate'
+public readonly struct MyDate : IParsable<DateOnly>
+{ ... }
+```
+
+**Fix**:
+
+Pass the `MyDate` type as the type parameter for the `IParsable<TSelf>` interface.
+
+```csharp
+using System;
+
+// No warning
+public readonly struct MyDate : IParsable<MyDate>
+{ ... }
+```
+
+## When to suppress errors
+
+Do not suppress a warning from this rule.
+
+## See also
+
+- [Usage warnings](usage-warnings.md)

docs/fundamentals/code-analysis/quality-rules/index.md

@@ -203,6 +203,7 @@ The following table lists code quality analysis rules.
 > | [CA2256: All members declared in parent interfaces must have an implementation in a DynamicInterfaceCastableImplementation-attributed interface](ca2256.md) | Types attributed with `DynamicInterfaceCastableImplementationAttribute` act as an interface implementation for a type that implements the `IDynamicInterfaceCastable` type. As a result, it must provide an implementation of all of the members defined in the inherited interfaces, because the type that implements `IDynamicInterfaceCastable` will not provide them otherwise. |
 > | [CA2257: Members defined on an interface with 'DynamicInterfaceCastableImplementationAttribute' should be 'static'](ca2257.md) | Since a type that implements `IDynamicInterfaceCastable` may not implement a dynamic interface in metadata, calls to an instance interface member that is not an explicit implementation defined on this type are likely to fail at run time. Mark new interface members `static` to avoid run-time errors. |
 > | [CA2258: Providing a 'DynamicInterfaceCastableImplementation' interface in Visual Basic is unsupported](ca2258.md) | Providing a functional `DynamicInterfaceCastableImplementationAttribute`-attributed interface requires the Default Interface Members feature, which is unsupported in Visual Basic. |
+> | [CA2260: Implement generic math interfaces correctly](ca2260.md) | Generic math interfaces require the derived type itself to be used for the self-recurring type parameter. |
 > | [CA2300: Do not use insecure deserializer BinaryFormatter](ca2300.md) | Insecure deserializers are vulnerable when deserializing untrusted data. An attacker could modify the serialized data to include unexpected types to inject objects with malicious side effects. |
 > | [CA2301: Do not call BinaryFormatter.Deserialize without first setting BinaryFormatter.Binder](ca2301.md) | Insecure deserializers are vulnerable when deserializing untrusted data. An attacker could modify the serialized data to include unexpected types to inject objects with malicious side effects. |
 > | [CA2302: Ensure BinaryFormatter.Binder is set before calling BinaryFormatter.Deserialize](ca2302.md) | Insecure deserializers are vulnerable when deserializing untrusted data. An attacker could modify the serialized data to include unexpected types to inject objects with malicious side effects. |

docs/fundamentals/code-analysis/quality-rules/usage-warnings.md

@@ -61,3 +61,4 @@ Usage rules support proper usage of .NET.
 |[CA2256: All members declared in parent interfaces must have an implementation in a DynamicInterfaceCastableImplementation-attributed interface](ca2256.md) | Types attributed with `DynamicInterfaceCastableImplementationAttribute` act as an interface implementation for a type that implements the `IDynamicInterfaceCastable` type. As a result, it must provide an implementation of all of the members defined in the inherited interfaces, because the type that implements `IDynamicInterfaceCastable` will not provide them otherwise. |
 |[CA2257: Members defined on an interface with 'DynamicInterfaceCastableImplementationAttribute' should be 'static'](ca2257.md) | Since a type that implements `IDynamicInterfaceCastable` may not implement a dynamic interface in metadata, calls to an instance interface member that is not an explicit implementation defined on this type are likely to fail at run time. Mark new interface members `static` to avoid run-time errors. |
 |[CA2258: Providing a 'DynamicInterfaceCastableImplementation' interface in Visual Basic is unsupported](ca2258.md) | Providing a functional `DynamicInterfaceCastableImplementationAttribute`-attributed interface requires the Default Interface Members feature, which is unsupported in Visual Basic. |
+| [CA2260: Implement generic math interfaces correctly](ca2260.md) | Generic math interfaces require the derived type itself to be used for the self-recurring type parameter. |

docs/fundamentals/toc.yml

@@ -1429,6 +1429,8 @@ items:
             href: code-analysis/quality-rules/ca2257.md
           - name: CA2258
             href: code-analysis/quality-rules/ca2258.md
+          - name: CA2260
+            href: code-analysis/quality-rules/ca2260.md
       - name: Code style rules
         items:
         - name: Overview