*Breaks are formatted with a monotonically increasing numbered list to allow them to referenced via shorthand (i.e., "known break #1").
Each entry should include a short description of the break, followed by either a link to the issue describing the full details of the break or the full details of the break inline.*
1. Previously, we allowed adding a module with `Microsoft.CodeAnalysis.EmbeddedAttribute` or `System.Runtime.CompilerServices.NonNullTypesAttribute` types declared in it.
1. https://github.com/dotnet/roslyn/issues/27800 C# will now preserve left-to-right evaluation for compound assignment addition/subtraction expressions where the left-hand side is dynamic. In this example code:
``` C#
class DynamicTest
{
public int Property { get; set; }
static dynamic GetDynamic() => return new DynamicTest();
static int GetInt() => 1;
public static void Main() => GetDynamic().Property += GetInt();
}
```
- Previous versions of Roslyn would have evaluated this as:
1. GetInt()
2. GetDynamic()
3. get_Property
4. set_Property
- We now evaluate it as
1. GetDynamic()
2. get_Property
3. GetInt()
4. set_Property
2. Previously, we allowed adding a module with `Microsoft.CodeAnalysis.EmbeddedAttribute` or `System.Runtime.CompilerServices.NonNullTypesAttribute` types declared in it.
In Visual Studio 2019, this produces a collision error with the injected declarations of those types.
2. Previously, you could refer to a `System.Runtime.CompilerServices.NonNullTypesAttribute` type declared in a referenced assembly.
3. Previously, you could refer to a `System.Runtime.CompilerServices.NonNullTypesAttribute` type declared in a referenced assembly.
In Visual Studio 2019, the type from assembly is ignored in favor of the injected declaration of that type.
