mirror of
https://github.com/icsharpcode/ILSpy.git
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Siegfried Pammer
a7f2a98f8b
Emitting a member reference starts from its shortest spelling, which in the output's name-lookup context may bind to a different member than the one the IL referenced. Six places re-resolved what they were about to write and, while it did not bind back, escalated to a more explicit spelling and tried again: field accesses, calls, constructor calls, accessors, and the two method group forms. Each kept its own retry state, and each held targetResolveResult in sync with requireTarget by hand. Disambiguator owns that loop. A For* factory per form of reference builds one, escalates and hands it back finished, naming the steps that form prefers and whether it is written with invocation syntax - the one thing an IMethod does not say, since a method group is not, a property access is not even though it is a call in IL, and a parameterized property's accessor is despite being an accessor. Everything that answers "does this spelling still reach the member" moves with the loop, including the two checks that are asked standalone, and the decision to write type arguments up front for a method whose arguments cannot infer them, which belongs next to the step that takes that guess back. What is left in CallBuilder builds call syntax. CheckSimpleCall now takes its compilation from the resolver rather than the type system; they are the same one. The escalations are already named by ReferenceTransformation, which is also the record of what has been applied, so the allowed-set gating becomes one test and clearing a bit to stop a step repeating becomes unnecessary: one use spends a step, which is also what ends the loop. Spent is tracked apart from what is in effect for the single escalation that is not monotone, where a protected member of a base type cannot be reached through a cast target and the qualifier has to be dropped again. Assisted-by: Claude:claude-opus-5[1m]:Claude Code
ILSpy 
ILSpy is the open-source, cross-platform .NET assembly browser and decompiler. The desktop UI runs on Windows, Linux, and macOS (built on Avalonia).
Download: latest release | latest CI build (master) | Microsoft Store (RTM versions only)
Decompiler Frontends
Aside from the cross-platform desktop UI ILSpy (downloadable via Releases, see also plugins), the following other frontends are available:
- Visual Studio 2022/2026 ship with decompilation support for F12 enabled by default (using our engines v8.2 and v9.1 respectively).
- Our Visual Studio 2022/2026 extension marketplace
- Our Visual Studio Code Extension repository | marketplace | open-vsx
- Our dotnet tool for Linux/Mac/Windows - check out ILSpyCmd in this repository | dotnet tool install
- C# for Visual Studio Code ships with decompilation support as well. To enable, activate the setting "Enable Decompilation Support".
- Our ICSharpCode.Decompiler and ILSpyX NuGet packages for your own projects
- Our Linux/Mac/Windows PowerShell cmdlets in this repository
Features
- Decompilation to C# (check out the language support status)
- Whole-project decompilation
- Open from NuGet feed, open from running process in addition to disk and GAC (Windows-only)
- Search for types/methods/properties (learn about the options)
- Hyperlink-based type/method/property navigation, bookmarks
- Base/Derived types navigation, history
- Assembly metadata explorer (feature walkthrough)
- BAML to XAML decompiler, !AvaloniaResources support
- ReadyToRun binary support for .NET Core (see the tutorial)
- Extensible via plugins
- Additional features in DEBUG builds (for the devs)
License
ILSpy is distributed under the MIT License. Please see the About doc for details, as well as third party notices for included open-source libraries.
How to build
Windows:
- Make sure PowerShell 7+ is installed (Windows PowerShell at least version 5.0 works as well)
- Clone the ILSpy repository using git.
- Execute
git submodule update --init --recursiveto download the ILSpy-Tests submodule (used by some test cases). - Install Visual Studio (documented version: 18.0/2026). You need the following workload components:
- Workload ".NET Desktop Development". This workload includes the .NET Framework 4.8 SDK and the .NET Framework 4.7.2 targeting pack, as well as the .NET 10.0 SDK (ILSpy.csproj targets .NET 10.0, but we have net472 projects too). Our unit tests require .NET 11.0 SDK.
- Workload "Visual Studio extension development" (Note: ILSpy.VSExtensions.slnx is separate from ILSpy.sln and thus this workload is optional)
- Individual Component "MSVC v143 - VS 2022 C++ x64/x86 build tools" (or similar)
- The VC++ toolset is optional; if present it is used for
editbin.exeto modify the stack size used by ILSpy.exe from 1MB to 16MB, because the decompiler makes heavy use of recursion, where small stack sizes lead to problems in very complex methods.
- The VC++ toolset is optional; if present it is used for
- Open ILSpy.sln in Visual Studio.
- NuGet package restore will automatically download further dependencies
- Run project "ILSpy" for the ILSpy UI
- Use the Visual Studio "Test Explorer" to see/run the tests
- If you are only interested in a specific subset of ILSpy, you can also use
- ILSpy.Desktop.slnf: for the cross-platform Avalonia UI and its tests
- ILSpy.XPlat.slnf: for the cross-platform CLI (ilspycmd) or PowerShell cmdlets
- ILSpy.VSExtensions.slnx: for the Visual Studio extensions
Note: Visual Studio includes a version of the .NET SDK that is managed by the Visual Studio installer - once you update, it may get upgraded too. Please note that ILSpy is only compatible with the .NET 11.0 SDK and Visual Studio will refuse to load some projects in the solution (and unit tests will fail). If this problem occurs, please manually install the .NET 11.0 SDK from here.
Unix / Mac:
- Make sure .NET 10.0 SDK (for run) and .NET 11.0 SDK (for tests) is installed. Better yet, use dotnetup with SDK channel preview.
- Make sure PowerShell is installed (formerly known as PowerShell Core)
- Clone the repository using git.
- Execute
git submodule update --init --recursiveto download the ILSpy-Tests submodule (used by some test cases). - Use
dotnet build ILSpy.Desktop.slnfto build the cross-platform Avalonia desktop UI; run it withdotnet run --project ILSpy. - Use
dotnet build ILSpy.XPlat.slnfto build only the CLI tool (ilspycmd) and PowerShell cmdlets.
We recommend Visual Studio Code or derivatives together with DotRush, which is also available for derivatives of VS Code.
How to contribute
- Report bugs
- If you want to contribute a pull request, please add https://github.com/icsharpcode/ILSpy/blob/master/BuildTools/pre-commit to your
.git/hooksto prevent checking in code with wrong formatting. We use tabs and not spaces. The build server runs the same script, so any pull requests using wrong formatting will fail.
Current and past contributors.
Privacy Policy for ILSpy
ILSpy does not collect any personally identifiable information, nor does it send user files to 3rd party services. ILSpy does not use any APM (Application Performance Management) service to collect telemetry or metrics.