ILSpy 9.x is based on .NET 8.0. All artifacts except the self-contained distribution are built framework-dependent, which means .NET 8.0.x or later must be installed prior to starting ILSpy.

Generic themes of this release were refactoring the old WPF code base and moving away from platform-dependent implementations to make reuse easier via our ILSpyX package.

A few notable picks from the "What's new" department for you to check out: WebCIL and standalone ECMA-335 metadata support, as well as diagramming (either via ilspycmd or assembly context menu). And in general quality-of-life improvements like the ability to disable automatic assembly loading, performance improvements via DATAS and future-proofing for .NET 10.

New Language Features

Add support for C# 12 primary constructors.
Add support for C# 12 'ref readonly' parameters
Added support for switch on (ReadOnly)Span<char> using a compiler-generated hash function.
Added new a.GetValueOrDefault(b) -> a ?? b transform for side-effect-free default values.
Support types that provide DisposeAsync without implementing IAsyncDisposable.
Updated pattern detection to Roslyn 4.12

Enhancements

Added support for reading WebCIL assemblies (IL embedded in WASM) (see #3184)
Added support for reading standalone ECMA-335 metadata (portable PDB and other metadata blobs) (see #3149)
#3118: Add "Clear assembly list" menu item.
#2893: Add option to disable automatic assembly loading.
Allow implicit conversions in switch
IL output: Add indentation level to make it easier to see custom attributes belonging to interface implementations.
IL output: Print metadata token of custom attribute.
Replace native interop CommandLineToArgvW with parsing in Process.Unix.cs from System.Diagnostics.Process #3201
Natural Sort without interop #3196
AOT and x-plat changes #3203
Allow running tests on ARM64 (see #3231)
Alow collecting analyzers annotated with ExportAnalyzerAttribute (see #3239)
Fix #3237: Use ref readonly locals for readonly.ldelema
Fix #3001: Support new resources format in ResourcesFile/ResXResourceWriter
Fix #3134: Include newobj, initobj and call instructions in TypeInstantiatedByAnalyzer
Fix #3089: Add comment regarding .constraint prefix expressed as cast in C#
Fix #3372: Fix loading a DLL that contains byte sequences matching ZIP central directory
Use Microsoft.Sbom.Targets in NuGets #3346

Contributions

Diagramming feature by @h0lg (see #3324)
Various WPF-related refactorings by @tom-englert (see #3257, #3266, #3274, #3283, #3285, #3291, #3292, #3294, #3295, #3297, #3298, #3299, #3302, #3308, #3314, #3325 and #3335)
High DPI fixes by @CreateAndInject (see #3348 and #3350)
TreeView: Add referenced types, members and exported types under references (#3092, @fowl2)
Adjust colors of AvalonEdit built-in highlightings for dark themes (#3138, @ltrzesniewski)
Add support for Mono C# compiler 2.6.4 pinned region with array variable (#3110, @ElektroKill)
Add smooth scrolling to settings panels and DecompilerTextView (see #3244 by @tom-englert)
Ignore empty version directories of dotnet (#3265 by @Herrmel)
Missing DecompilerSettings by @naratteu (see #3356)
Fix metadata display of DynamicLocalVariable and DefaultNamespace custom debug information (#3111, @ElektroKill)
Read and use tuple element names and dynamic type information from PDBs (#3114, @ElektroKill)
Bugfix: infinite loop in DetermineEffectiveAccessibility (#3164, @yzdeveloper)
Decompiler Settings: Checkbox in group header does not reflect state of the group (see #3252 by @tom-englert)
Fix Derived Types Node always being empty (#3280 by @Applesauce314)

Performance

Activate Dynamic Adaptation To Application Sizes (DATAS) (#3122).
RDP hardware acceleration (#3122): Enabling hardware acceleration for Remote Desktop Protocol (RDP) to boost performance.
Performance: Initialize ToolPanes in DockWorkspace.InitializeLayout() instead of the property getter to avoid WPF seeing them in InitializeComponent() and rendering all panes docked at the right before the layout is properly initialized.

Breaking Changes

ICSharpCode.Decompiler: Added MetadataFile base class for PEFile
ICSharpCode.Decompiler: IModule.PEFile is now named IModule.MetadataFile
ICSharpCode.Decompiler/ILSpyX: Added IFileLoader API to allow for easier extensibility of supported file formats (see #3191)
ILSpy: Split BAML decompiler into library and add-in (see #3178)
ILSpy/ILSpyX: Moved non-UI analyzer API to ILSpyX (see #3186)
ICSharpCode.Decompiler: IProjectFileWriter and IProjectInfoProvider APIs are now public (see #3151 and #3191)
@file support with breaking changes to command line options #3205
New single instance handling #3212
Remove IsRef, IsOut and IsIn flags from IParameter
Replace ParameterModifiers with ReferenceKind.

Bug fixes

Fix #3072: Ignoring resources with the same name as a namespace.
Fix bug in UnknownType: Ensuring that the FullName of nested unknown types contains the outer type name(s), not just the namespace and nested type name.
Fix #3153: Always using SHA1 for public key tokens.
Fix ILSpy for ZIP files/VSIX with bundle signatures: Enabling ILSpy to open ZIP files and VSIX packages containing bundle signatures.
Omit package entries from the treeview that denote the directory.
Fix #3142: Exception when analyzing source of library with global assembly attributes
Fix #3113: Remove GetAlternativeName and instead reuse existing names, if there are no conflicts.
Fix #3197: Bug when trying to read a bundle/archive file
Fix #3189: Support primitive types in Expression.Constant(object) pattern in Expression Trees
Fix #3209: Ensure using directives are added for extension methods in higher level patterns such as: foreach -> GetEnumerator(), collection initializer -> Add() and deconstruction -> Deconstruct().
Fix #3255: Ignore exceptions while decoding sequence point blobs.
Fix #2166: Unnecessary uint casts/conversions for certain bitwise operations
Fix #3310: Filter out copy-constructor only if it's an actual record type.
Fix #3319: KeyDownEvent field reference was replaced with KeyDown event reference.
Fix #3349: Make ILSpy ready for .NET 10
Fix #3361: switch-value conversion was losing its target type.

And many other fixes, for a full list click here.

New Language Features

Add support for C# 12 primary constructors.

Add support for C# 12 'ref readonly' parameters

Added support for switch on (ReadOnly)Span<char> using a compiler-generated hash function.

Added new a.GetValueOrDefault(b) -> a ?? b transform for side-effect-free default values.

Support types that provide DisposeAsync without implementing IAsyncDisposable.

Updated pattern detection to Roslyn 4.12

Enhancements

Added support for reading WebCIL assemblies (IL embedded in WASM) (see #3184)

Added support for reading standalone ECMA-335 metadata (portable PDB and other metadata blobs) (see #3149)

#3118: Add "Clear assembly list" menu item.

#2893: Add option to disable automatic assembly loading.

Allow implicit conversions in switch

IL output: Add indentation level to make it easier to see custom attributes belonging to interface implementations.

IL output: Print metadata token of custom attribute.

Replace native interop CommandLineToArgvW with parsing in Process.Unix.cs from System.Diagnostics.Process #3201

Natural Sort without interop #3196

AOT and x-plat changes #3203

Allow running tests on ARM64 (see #3231)

Alow collecting analyzers annotated with ExportAnalyzerAttribute (see #3239)

Fix #3237: Use ref readonly locals for readonly.ldelema

Fix #3001: Support new resources format in ResourcesFile/ResXResourceWriter

Fix #3134: Include newobj, initobj and call instructions in TypeInstantiatedByAnalyzer

Fix #3089: Add comment regarding .constraint prefix expressed as cast in C#

Fix #3372: Fix loading a DLL that contains byte sequences matching ZIP central directory

Use Microsoft.Sbom.Targets in NuGets #3346

Contributions

Diagramming feature by @h0lg (see #3324)

Various WPF-related refactorings by @tom-englert (see #3257, #3266, #3274, #3283, #3285, #3291, #3292, #3294, #3295, #3297, #3298, #3299, #3302, #3308, #3314, #3325 and #3335)

High DPI fixes by @CreateAndInject (see #3348 and #3350)

TreeView: Add referenced types, members and exported types under references (#3092, @fowl2)

Adjust colors of AvalonEdit built-in highlightings for dark themes (#3138, @ltrzesniewski)

Add support for Mono C# compiler 2.6.4 pinned region with array variable (#3110, @ElektroKill)

Add smooth scrolling to settings panels and DecompilerTextView (see #3244 by @tom-englert)

Ignore empty version directories of dotnet (#3265 by @Herrmel)

Missing DecompilerSettings by @naratteu (see #3356)

Fix metadata display of DynamicLocalVariable and DefaultNamespace custom debug information (#3111, @ElektroKill)

Read and use tuple element names and dynamic type information from PDBs (#3114, @ElektroKill)

Bugfix: infinite loop in DetermineEffectiveAccessibility (#3164, @yzdeveloper)

Decompiler Settings: Checkbox in group header does not reflect state of the group (see #3252 by @tom-englert)

Fix Derived Types Node always being empty (#3280 by @Applesauce314)

Performance

Activate Dynamic Adaptation To Application Sizes (DATAS) (#3122).

RDP hardware acceleration (#3122): Enabling hardware acceleration for Remote Desktop Protocol (RDP) to boost performance.

Performance: Initialize ToolPanes in DockWorkspace.InitializeLayout() instead of the property getter to avoid WPF seeing them in InitializeComponent() and rendering all panes docked at the right before the layout is properly initialized.

Breaking Changes

ICSharpCode.Decompiler: Added MetadataFile base class for PEFile

ICSharpCode.Decompiler: IModule.PEFile is now named IModule.MetadataFile

ICSharpCode.Decompiler/ILSpyX: Added IFileLoader API to allow for easier extensibility of supported file formats (see #3191)

ILSpy: Split BAML decompiler into library and add-in (see #3178)

ILSpy/ILSpyX: Moved non-UI analyzer API to ILSpyX (see #3186)

ICSharpCode.Decompiler: IProjectFileWriter and IProjectInfoProvider APIs are now public (see #3151 and #3191)

@file support with breaking changes to command line options #3205

New single instance handling #3212

Remove IsRef, IsOut and IsIn flags from IParameter

Replace ParameterModifiers with ReferenceKind.

Bug fixes

Fix #3072: Ignoring resources with the same name as a namespace.

Fix bug in UnknownType: Ensuring that the FullName of nested unknown types contains the outer type name(s), not just the namespace and nested type name.

Fix #3153: Always using SHA1 for public key tokens.

Fix ILSpy for ZIP files/VSIX with bundle signatures: Enabling ILSpy to open ZIP files and VSIX packages containing bundle signatures.

Omit package entries from the treeview that denote the directory.

Fix #3142: Exception when analyzing source of library with global assembly attributes

Fix #3113: Remove GetAlternativeName and instead reuse existing names, if there are no conflicts.

Fix #3197: Bug when trying to read a bundle/archive file

Fix #3189: Support primitive types in Expression.Constant(object) pattern in Expression Trees

Fix #3209: Ensure using directives are added for extension methods in higher level patterns such as: foreach -> GetEnumerator(), collection initializer -> Add() and deconstruction -> Deconstruct().

Fix #3255: Ignore exceptions while decoding sequence point blobs.

Fix #2166: Unnecessary uint casts/conversions for certain bitwise operations

Fix #3310: Filter out copy-constructor only if it's an actual record type.

Fix #3319: KeyDownEvent field reference was replaced with KeyDown event reference.

Fix #3349: Make ILSpy ready for .NET 10

Fix #3361: switch-value conversion was losing its target type.

And many other fixes, for a full list click here.

ILSpy

ILSpy 9.0

New Language Features

Enhancements

Contributions

Performance

Breaking Changes

Bug fixes

More C# Projects

v2rayN

jellyfin

PowerShell

Files

ILSpy 9.0

New Language Features

Enhancements

Contributions

Performance

Breaking Changes

Bug fixes

More C# Projects

v2rayN

jellyfin

PowerShell

Files