Current language feature status of the master branch is detailed in #829. The following list shows all completed language versions.

• Language features that are checked are implemented in the current master branch of ILSpy and have a minimal test suite at least.
• Language features that are crossed out will likely never be implemented in the decompiler, either because
  • they are not reproducible from compiled binaries (e.g. constant interpolated strings, Caller info attributes),
  • or they are of limited use and would require too much work to implement in the decompiler (e.g. static and global using directives, expression bodied members).

C# 1

• XmlDoc (see also #163)
• switch(string) (see Switch tag as well)
• goto case -> #316
• params
• unsafe -> #924

C# 2 (VS 2005)

• Generics
• Partial types: These are not applicable in decompiled code, as the code is decompiled into exactly one part.
• Anonymous methods
• Iterators
• Nullable types -> Nullable<T>
• Getter/setter separate accessibility
• Method group conversions (delegates)
• Co- and Contra-variance for delegates and interfaces
• Static classes
• Delegate inference

C# 3 (VS 2008)

• Implicitly typed local variables
• Object and collection initializers
• Auto-Implemented properties
• Anonymous types
• Extension methods
• Query expressions
• Lambda expression
• Expression trees
• Partial methods: These are not applicable in decompiled code, as the code is decompiled into exactly one part.

C# 4 (VS 2010)

• Dynamic binding -> #154
• Named arguments -> #950
• Optional arguments -> #1083
• Generic co- and contravariance
• Embedded interop types ("NoPIA"): TODO

C# 5 (VS 2012)

• Asynchronous methods
• Caller info attributes: In general it's not possible to remove the compiler-generated values, because that would require us to produce the exact original source code.

C# 6 (VS 2015)

• Compiler-as-a-service (Roslyn)
• Import of static type members into namespace: Currently, there are no plans to emit using static declarations.
• Exception filters (see #761)
• Await in catch/finally blocks
• Auto property initializers
• Default values for getter-only properties
• Expression-bodied members
• Null propagator (null-conditional operator, succinct null checking)
• String interpolation (see #1012)
• nameof operator: Similar to caller info attributes, this would require us to reproduce the exact source code. We could emit nameof expressions in certain situations, e.g. throw new ArgumentException(nameof(parameter));, but currently there are no plans to add this.
• Dictionary initializer
• Allow 'Add' extension methods in collection initializers