Edit pass

docs/csharp/language-reference/compiler-messages/ref-struct-errors.md

@@ -37,53 +37,50 @@ ms.date: 07/30/2024
 - [**CS8344**](#ref-struct-interface-implementations): *`foreach` statement cannot operate on enumerators in async or iterator methods because type is a `ref struct` or a type parameter that allows `ref struct`.*
 - [**CS8345**](#ref-safety-violations): *Field or auto-implemented property cannot be of type unless it is an instance member of a `ref struct`.*
 - [**CS9048**](#ref-safety-violations): *The `scoped` modifier can be used for refs and `ref struct` values only.*
-- [**CS9050**](#compiler-error-cs9050): *A `ref` field cannot refer to a `ref struct`.*
+- [**CS9050**](#ref-safety-violations): *A `ref` field cannot refer to a `ref struct`.*
 - [**CS9059**](#ref-safety-violations): *A ref field can only be declared in a ref struct.*
 - [**CS9241**](#ref-struct-interface-implementations): *'ref struct' is already specified.*
 - [**CS9242**](#ref-struct-interface-implementations): *The 'allows' constraint clause must be the last constraint specified.*
 - [**CS9243**](#ref-struct-interface-implementations): *Cannot allow ref structs for a type parameter known from other constraints to be a class.*
 - [**CS9244**](#ref-struct-interface-implementations): *The type may not be a `ref struct` or a type parameter allowing ref structs in order to use it as parameter in the generic type or method.*
 - [**CS9245**](#ref-struct-interface-implementations): *Type cannot implement interface member for `ref struct` type.*
 - [**CS9246**](#ref-struct-interface-implementations): *A non-virtual instance interface member cannot be accessed on a type parameter that allows ref struct.*
-- [**CS9247**](#ref-struct-interface-implementations): *foreach statement cannot operate on enumerators of type '{0}' because it is a type parameter that allows ref struct and it is not known at compile time to implement IDisposable.*
+- [**CS9247**](#ref-struct-interface-implementations): *foreach statement cannot operate on enumerators of type because it is a type parameter that allows ref struct and it is not known at compile time to implement `IDisposable`.*
 
-## ref struct interface implementations
+## ref safety violations
 
-More content here.
+- **CS8345**: *Field or auto-implemented property cannot be of type unless it is an instance member of a `ref struct`.*
+- **CS9048**: *The `scoped` modifier can be used for refs and `ref struct` values only.*
+- **CS9050**: *A `ref` field cannot refer to a `ref struct`.*
+- **CS9059**: *A `ref` field can only be declared in a `ref struct`.*
 
-## ref safety violations
+A [`ref struct`](../builtin-types/ref-struct.md) type can include `ref` fields. Other types aren't allowed `ref` fields. The compiler enforces restrictions on the declarations and use of `ref struct` types to enforce ref safety rules on instances of any `ref struct` type:
 
-Even more content goes here.
+- Only `ref struct` types can contain auto-implemented `ref` properties.
+- Only `ref struct` types or `ref` variables can have the `scoped` modifier.
+- A `ref` field can be declared only in a `ref struct` type.
+- A `ref` field can't refer to a `ref struct` type/
 
-## Compiler Error CS9050
+Violating any of these rules produces one of the listed errors. If you intended to use that language feature, convert the type to a `ref struct`. Otherwise, remove the disallowed construct.
 
-A `ref` field cannot refer to a `ref struct`.
+## ref struct interface implementations
 
-The compiler does not support the `ref` modifier on a field within a struct (to declare a stack-allocated field) of a type already declared stack-allocated (`ref struct`).
+- **CS8343**: *`ref structs` cannot implement interfaces*
+- **CS8344**: *`foreach` statement cannot operate on enumerators in async or iterator methods because type is a `ref struct` or a type parameter that allows `ref struct`.*
+- **CS9241**: *'ref struct' is already specified.*
+- **CS9242**: *The 'allows' constraint clause must be the last constraint specified.*
+- **CS9243**: *Cannot allow ref structs for a type parameter known from other constraints to be a class.*
+- **CS9244**: *The type may not be a `ref struct` or a type parameter allowing ref structs in order to use it as parameter in the generic type or method.*
+- **CS9245**: *Type cannot implement interface member for `ref struct` type.*
+- **CS9246**: *A non-virtual instance interface member cannot be accessed on a type parameter that allows ref struct.*
+- **CS9247**: *foreach statement cannot operate on enumerators of type because it is a type parameter that allows ref struct and it is not known at compile time to implement `IDisposable`.*
 
-The following sample generates CS9050:
+Prior to C# 13, [`ref struct`](../builtin-types/ref-struct.md) types can't implement interfaces; the compiler generates *CS8343*. Beginning with C# 13, `ref struct` types can implement interfaces, subject to the following rules:
 
-```csharp
-// CS9050.cs (0,0)
-ref struct Color
-{
-    public float r, g, b;
-}
-ref struct Group
-{
-    public ref Color color;
-}
-```
+- A `ref struct` can't be converted to an instance of an interface it implements. This restriction includes the implicit conversion when you use a `ref struct` type as an argument when the parameter is an interface type. The conversion results in a boxing conversion, which violates ref safety.
+- A `ref struct` that implements an interface *must* implement all interface members. The `ref struct` must implement members where the interface includes a default implementation.
 
-In this example, it is most likely a typo to have included a `ref` modifier on a field of a `ref struct` type within the declaration of a `ref struct`.  Removing the `ref` modifier corrects this error.
+Beginning with C# 13, a `ref struct` can be used as a type argument for a generic type parameter, if and only if the generic type parameter has the [`allows ref struct`](../../programming-guide/generics/constraints-on-type-parameters.md#allows-ref-struct) anti-constraint. When you use the `allows ref struct` anti-constraint you must follow these rules:
 
-```csharp
-ref struct Color
-{
-    public float r, g, b;
-}
-ref struct Group
-{
-    public Color color;
-}
-```
+- A `ref struct` is used as a type argument, the type parameter *must* have the `allows ref struct` anti-constraint.- The `allows ref struct` anti-constraint must be last in the `where` clause for that parameter
+- Uses of instances the type parameter must obey ref safety rules.