Language Feature Status

This document reflects the status, and planned work in progress, for the compiler team. It is a live document and will be updated as work progresses, features are added / removed, and as work on feature progresses. This is not an exhaustive list of our features but rather the ones which have active development efforts behind them.

The "Feature" column contains a link to the championed proposal or doc for the feature.
The "State" column contains a link to the test plan issue for the feature. The test plan should have a "Feature - XYZ" label, which is also used on PRs and issues for the feature.

Working Set C#

Merged features should be in the bottom portion of the table (in descending order from earliest to latest merged), while in-progress features should be in the top portion of the table.
When a feature is merged to the main branch, its entry should be moved to the bottom of the table and its "State" value should be updated to record the relevant version number.

Feature	Branch	State	Developer	Reviewer	IDE Buddy	LDM Champ
Dictionary expressions	dictionary-expressions	In progress	333fred	CyrusNajmabadi, jcouv	CyrusNajmabadi	CyrusNajmabadi
Unions	Unions	In Progress	AlekseyTs	RikkiGibson, jjonescz	TBD	MadsTorgersen
Closed class hierarchies	closed-class	In progress	RikkiGibson	AlekseyTs, jjonescz	TBD	mattwar
Unsafe evolution	UnsafeEvolution	In progress	jjonescz	333fred, jcouv	TBD	agocke
Extension indexers	extensions	In progress	jcouv	AlekseyTs, CyrusNajmabadi	CyrusNajmabadi	jcouv
ExtendedLayoutAttribute	main	Merged into 18.3	jkoritzinsky	333fred, jcouv
Runtime Async	runtime-async-streams	Main feature merged into main in preview	333fred	jcouv, RikkiGibson
Collection expression arguments	collection-expression-arguments	Merged into .NET 11 p1 and VS 18.4	CyrusNajmabadi	333fred, jcouv	CyrusNajmabadi	CyrusNajmabadi

Working Set VB

C# 14.0

Feature	Branch	State	Developer	Reviewer	IDE Buddy	LDM Champ
field keyword in properties	field-keyword	Merged into 17.12p3	Youssef1313, cston	333fred, RikkiGibson	CyrusNajmabadi	CyrusNajmabadi
First-class Span Types	FirstClassSpan	Merged into 17.13p1	jjonescz	cston, 333fred		333fred, stephentoub
Unbound generic types in nameof	PR	Merged into 17.13p2	CyrusNajmabadi	jcouv, AlekseyTs	CyrusNajmabadi	CyrusNajmabadi
String literals in data section as UTF8	PR	Merged into 17.13p4	jjonescz	AlekseyTs, cston	N/A	N/A
Simple lambda parameters with modifiers	PR	Merged into 17.14p1	CyrusNajmabadi	jjonescz, cston	CyrusNajmabadi	CyrusNajmabadi
Partial Events and Constructors	PartialEventsCtors	Merged into 17.14p3	jjonescz	cston, RikkiGibson	CyrusNajmabadi	jaredpar
Extensions	extensions	Merged into 17.14p3	jcouv, AlekseyTs	jjonescz, TBD	CyrusNajmabadi	MadsTorgersen
Null-conditional assignment	null-conditional-assignment	Merged into 17.14p3	RikkiGibson	cston, jjonescz	CyrusNajmabadi	RikkiGibson
Ignored directives	PR	Merged into 17.14p3	jjonescz	RikkiGibson, jaredpar	CyrusNajmabadi	jaredpar
User Defined Compound Assignment Operators	UserDefinedCompoundAssignment	Merged to main	AlekseyTs	333fred, cston	CyrusNajmabadi	AlekseyTs
Optional and named arguments in Expression trees	PR	Merged to main(https://github.com/dotnet/roslyn/issues/76934)	cston	333fred, AlekseyTs	CyrusNajmabadi	cston

VB in .NET 10

Feature	Branch	State	Developer	Reviewer	IDE Buddy	LDM Champ
Recognizing 'unmanaged' constraint	main	Merged into 17.13 P2	AlekseyTs	cston, 333fred	(no IDE impact)	jaredpar
Overload Resolution Priority	main	Merged into 17.13 P3	AlekseyTs	333fred, cston	(no IDE impact)	333fred

C# 13.0

Feature	Branch	State	Developer	Reviewer	IDE Buddy	LDM Champ
Escape character	N/A	Merged into 17.9p1	CyrusNajmabadi	jcouv, RikkiGibson	(no IDE impact)	CyrusNajmabadi
Method group natural type improvements	main	Merged into 17.9p2	jcouv	AlekseyTs, cston	(no IDE impact)	jcouv
Lock object	LockObject	Merged into 17.10p2	jjonescz	cston, RikkiGibson	CyrusNajmabadi (needs IDE fixer)	stephentoub
Implicit indexer access in object initializers	main	Merged into 17.9p3	jcouv	AlekseyTs, cston	(no IDE impact)
Params-collections	main	Merged to 17.10p3	AlekseyTs	RikkiGibson, 333fred	akhera99 (needs IDE fixer)	MadsTorgersen, AlekseyTs
Ref/unsafe in iterators/async	RefInAsync	Merged into 17.11p2	jjonescz	AlekseyTs, cston	(no IDE impact)
Overload Resolution Priority	main	Merged to 17.12p1	333fred	jcouv, cston	Not yet assigned	333fred
Partial properties	partial-properties	Merged into 17.11p3	RikkiGibson	jcouv, 333fred	Cosifne	333fred, RikkiGibson
Ref Struct Interfaces/allows ref struct constraint	RefStructInterfaces	Merged into 17.11p2	AlekseyTs	cston, jjonescz	ToddGrun	agocke, jaredpar
Collection expression better conversion from expression	main	Merged into 17.12p3	333fred	cston, AlekseyTs	(no IDE impact)	333fred, CyrusNajmabadi

C# 12.0

Feature	Branch	State	Developer	Reviewer	LDM Champ
ref readonly parameters	RefReadonly	Merged into 17.8p2	jjonescz	jcouv, AlekseyTs	akhera99
Collection Expressions	CollectionLiterals	Merged into 17.7p5	cston	333fred, RikkiGibson	CyrusNajmabadi
Interceptors (experimental feature)	interceptors	Merged into 17.7p3	RikkiGibson	cston, jcouv	akhera99
Inline Arrays	InlineArrays	Merged into 17.7p3	AlekseyTs	cston, jjonescz	Cosifne
nameof accessing instance members	main	Merged into 17.7p1	YairHalberstadt, jjonescz	333fred, AlekseyTs	333fred
Using aliases for any type	main	Merged into 17.6.P3	CyrusNajmabadi	jcouv cston	CyrusNajmabadi
Primary Constructors	PrimaryConstructors	Merged into 17.6.P2	AlekseyTs	cston, jjonescz	akhera99
Lambda optional parameters	lambda-default-parameters	Merged into 17.5p2	adamperlin, jjonescz	333fred, cston	captainsafia
Experimental attribute	main	Merged into 17.8p2	jcouv	cston, jjonescz	jcouv

C# 11.0

Feature	Branch	State	Developer	Reviewer	LDM Champ
File-local types	file-types	Merged into 17.4p1	RikkiGibson	jcouv, cston	stephentoub
ref fields	ref-fields	Merged into 17.3p3	cston	RikkiGibson, AlekseyTs	jaredpar
Required members	main	Merged into 17.3p2	333fred	jcouv, RikkiGibson	333fred
DIM for Static Members	DefaultInterfaceImplementation	Merged into 17.3p2	AlekseyTs	333fred, jcouv	MadsTorgersen
Numeric IntPtr	numeric-intptr	Merged into 17.3p2	jcouv	cston, 333fred	jcouv
Unsigned Right Shift	UnsignedRightShift	Merged into 17.3p1	AlekseyTs	333fred, jcouv	AlekseyTs
Utf8 String Literals	main	Merged into 17.3p1	AlekseyTs	cston, RikkiGibson	MadsTorgersen
Pattern matching on ReadOnlySpan<char>	patterns-span-char	Merged into 17.3p1	YairHalberstadt	cston, RikkiGibson	jcouv
Checked Operators	CheckedUserDefinedOperators	Merged into 17.3p1	AlekseyTs	333fred, chsienki	AlekseyTs
auto-default structs	main	Merged into 17.3p1	RikkiGibson	cston, jcouv
Newlines in interpolations	main	Merged in 17.1p1	CyrusNajmabadi	jcouv, chsienki	CyrusNajmabadi
List patterns	main	Merged in 17.1p2	alrz	jcouv, 333fred	333fred
Raw string literals	main	Merged into 17.2	CyrusNajmabadi	jcouv	CyrusNajmabadi
Cache delegates for static method group	main	Merged into 17.2	pawchen	AlekseyTs, jcouv	AlekseyTs
nameof(parameter)	main	Merged into 17.3p2	jcouv	AlekseyTs, RikkiGibson	jcouv
Relaxing Shift Operator	main	Merged into 17.3p2	AlekseyTs	333fred, jcouv	MadsTorgersen
Generic attributes	main	Merged into 17.0p4	AviAvni	RikkiGibson, jcouv	mattwar

C# 10.0

Feature	Branch	State	Developer	Reviewer	LDM Champ
Record structs	main	Merged into 16.11	jcouv	AlekseyTs, RikkiGibson	jcouv
Global Using Directive	main	Merged into 16.11	AlekseyTs	333fred, cston	AlekseyTs
Improved Definite Assignment	main	Merged into 17.0	RikkiGibson	jcouv	jaredpar
Constant Interpolated Strings	main	Merged into 16.9p3	kevinsun-dev	333fred	jaredar, agocke
Extended property patterns	main	Merged into 17.0	alrz	jcouv, 333fred	333fred
Sealed record ToString	main	Merged	thomaslevesque	jcouv	333fred
Source Generator V2 APIs	main	Merged into 17.0p2	chsienki	rikkigibson, jaredpar, cston	N/A
Mix declarations and variables in deconstruction	main	Merged into 16.10	YairHalberstadt	jcouv	MadsTorgersen
Async method builder override	main	Merged into 17.0p2	jcouv	cston, RikkiGibson	stephentoub
Enhanced #line directive	main	Merged into 17.0p2	cston	jcouv, RikkiGibson	MadsTorgersen
Lambda improvements	main	Merged into 17.0p2	cston	333fred, jcouv	jaredpar
Static Abstract Members In Interfaces C# 10 Preview	main	Merged into 17.0p2	AlekseyTs	333fred, RikkiGibson	MadsTorgersen
Interpolated string improvements	main	Merged into 17.0p3	333fred	AlekseyTs, chsienki	jaredpar
File-scoped namespace	main	Merged into 17.0p3	RikkiGibson	jcouv, chsienki	CyrusNajmabadi
Parameterless struct constructors	main	Merged into 17.0p3	cston	jcouv, 333fred	jcouv
Caller expression attribute	main	Merged into 17.0p3	Youssef1313	333fred,AlekseyTs	jcouv

VB 17.0

Feature	Branch	State	Developer	Reviewer	LDM Champ
Caller expression attribute	main	Merged into 17.0p3	Youssef1313	333fred,AlekseyTs	jcouv

VB 16.9

Feature	Branch	State	Developer	Reviewer	LDM Champ
Enable consumption of init-only properties	main	Merged (16.9p3)	AlekseyTs	jcouv	N/A

C# 9

Feature	Branch	State	Developer	Reviewer	LDM Champ
Target-typed new	target-typed-new	Merged into 16.7p1	alrz	jcouv	jcouv
Skip locals init	localsinit	Merged	t-camaia, agocke	jaredpar	agocke
Lambda discard parameters	main	Merged	jcouv	AlekseyTs, chsienki	jcouv
Native ints	main	Merged into 16.7p1	cston	333fred, gafter	jaredpar
Attributes on local functions	local-function-attributes	Merged	RikkiGibson	agocke	agocke
Function pointers	main	Merged into 16.7p3	333fred	AlekseyTs	jaredpar
Pattern matching improvements	main	Merged into 16.7p1	gafter	RikkiGibson,agocke	gafter
Static lambdas	main	Merged in 16.7p4	CyrusNajmabadi	jcouv	jcouv
Records	main	Merged into 16.7p3	agocke	gafter, 333fred	agocke
Target-typed conditional	target-typing	Merged into 16.7p4	gafter	agocke, RikkiGibson	gafter
Covariant Returns	covariant-returns	Merged into 16.8p2	gafter	AlekseyTs, agocke	gafter
Extension GetEnumerator	main	Merged into 16.8p2	YairHalberstadt	333fred	333fred
Module initializers	main	Merged in 16.7p4	RikkiGibson jnm2	AlekseyTs	gafter
Extending Partial	main	Merged into 16.7p2	RikkiGibson	chsienki	jaredpar
Top-level statements	SimplePrograms	Merged into 16.7p3	AlekseyTs	cston, RikkiGibson	MadsTorgersen

C# 8.0

Feature	Branch	State	Developer	Reviewer	LDM Champ
Default Interface Methods	main	Merged to dev16.1 preview2	AlekseyTs	gafter	gafter
Nullable reference type	main	Merged to dev16.0 preview1	cston, jcouv	AlekseyTs, 333fred	mattwar
Recursive patterns	main	Merged to dev16.0 preview2	gafter	agocke, cston	gafter
Async streams	main	Merged to dev16.0 preview1	jcouv	agocke	stephentoub
Enhanced using	main	Merged to dev16.0 preview2	chsienki	agocke	jaredpar
Ranges	main	Merged to dev16.0 preview1	agocke	cston	jaredpar
Null-coalescing Assignment	main	Merged to dev16.0 preview1	333fred	cston	gafter
Alternative interpolated verbatim strings	main	Merged to dev16.0 preview1	jcouv	cston	jcouv
stackalloc in nested contexts	main	Merged to dev16.2 preview1	gafter	-	gafter
Unmanaged generic structs	main	Merged to dev16.1 preview1	RikkiGibson	-	jaredpar
Static local functions	main	Merged in dev16.0 preview2	cston	jaredpar	jcouv
Readonly members	main	Merged to dev16.1 preview2	RikkiGibson	TBD	jaredpar

VB 16.0

Feature	Branch	State	Developer	Reviewer	LDM Champ
Line continuation comments	main	Merged in 16.1 (preview2)	paul1956	AlekseyTs	gafter
Relax null-coalescing operator requirements	main	Merged in 16.0	333fred	cston	gafter

C# 7.3

Feature	Branch	State	Developer	Reviewer	LDM Champ
blittable	None	Merged	None	-	jaredpar
Support == and != for tuples	main	Merged	jcouv	AlekseyTs	jcouv
strongname	main	Merged	tyoverby	agocke	jaredpar
Attribute on backing field	features/compiler	Merged	jcouv	AlekseyTs	jcouv
Ref Reassignment	main	Merged	agocke	vsadov	gafter
Constraints	main	Merged	OmarTawfik	vsadov	gafter
Stackalloc initializers	main	Merged	alrz	vsadov	jcouv
Custom fixed	main	Merged	vsadov	jcouv	jarepdar
Indexing movable fixed buffers	-	Merged	vsadov	jcouv	jarepdar
Improved overload candidates	features/compiler	Merged	gafter	cston	mattwar
Expression variables	main	Merged	AlekseyTs	gafter	AlekseyTs

C# 7.2 fixes

Feature	Branch	State	Developer	Reviewer	LDM Champ
ref and this ordering in ref extension	-	Merged	alrz	-	-
Tiebreaker for by-val and in overloads	main	Merged	OmarTawfik	-	-

C# 7.2

Feature	Branch	State	Developer	Reviewer	LDM Champ
ref readonly	main	Merged	vsadov, OmarTawfik	cston,gafter	jaredpar
interior pointer/Span<T>/ref struct	main	Merged	vsadov	gafter, jaredpar	jaredpar
non-trailing named arguments	main	Merged	jcouv	gafter	jcouv
private protected	main	Merged	gafter	jcouv	gafter
conditional ref operator	main	Merged	vsadov	cston	jaredpar
Digit separator after base specifier	main	Merged	alrz	-	gafter

C# 7.1

Feature	Branch	State	Developer	Reviewer	LDM Champ
Async Main	main	Merged	tyoverby	vsadov	stephentoub
Default Expressions	main	Merged	jcouv	cston	jcouv
Ref Assemblies	main	Merged (IDE and project-system integrations ongoing)	jcouv	gafter	N/A
Infer tuple names	main	Merged	jcouv	gafter	jcouv
Pattern-matching with generics	main	Merged	gafter	agocke	gafter

FAQ

• Is target version a guarantee?: No. It's explicitly not a guarantee. This is just the planned and ongoing work to the best of our knowledge at this time.
• Where are these State values defined?: Take a look at the Developing a Language Feature document.