Changelog For C# And VB Compilers - Roslyn

General information

The C# compiler now supports the 7.3 set of language features including:

System.Enum, System.Delegate and unmanaged constraints.
Ref local re-assignment: Ref locals and ref parameters can now be reassigned with the ref assignment operator (= ref).
Stackalloc initializers: Stack-allocated arrays can now be initialized, e.g. Span<int> x = stackalloc[] { 1, 2, 3 };.
Indexing movable fixed buffers: Fixed buffers can be indexed into without first being pinned.
Custom fixed statement: Types that implement a suitable GetPinnableReference can be used in a fixed statement.
Improved overload candidates: Some overload resolution candidates can be ruled out early, thus reducing ambiguities.
Expression variables in initializers and queries: Expression variables like out var and pattern variables are allowed in field initializers, constructor initializers and LINQ queries.
Tuple comparison: Tuples can now be compared with == and !=.
Attributes on backing fields: Allows [field: …] attributes on an auto-implemented property to target its backing field.

The C# compiler now supports:

Two minor languages changes where made to the 7.2 language features:

The C# compiler now supports the 7.2 set of language features including:

Support for the Span<T> type being used throughout Kestrel and CoreFX via the ref struct modifier.
readonly struct modifier: Enforces that all members of a struct are readonly. This adds a layer of correctness to code and also allows the compiler to avoid unnecessary copying of values when accessing members.
in parameters / ref readonly returns: Allows for unmodifiable structs to be safely passed and returned with the same efficiency as modifiable ref values.
private protected access modifier: Restricts access to the intersection of protected and internal.
Non-trailing named arguments: Named arguments can now be used in the middle of an argument list without the requirement that all following arguments are passed by name as well.

The C# compiler now supports the 7.1 set of language features, including:

The C# and VB compilers now can produce reference assemblies.

When you use C# 7.1 features in your project, lightbulb offers to upgrade your project’s language version, to “C# 7.1” or “latest”.

The C# compiler now supports the 7.0 set of language features, including: