This document details more advanced options for developing in this codebase. It is not quite necessary to follow it, but it is likely that you'll find something you'll need from here.
We recommend the following overall workflow when developing for this repository:
- Fork this repository
- Always work in your fork
- Always keep your fork up to date
Before updating your fork, run this command:
git remote add upstream https://github.com/dotnet/fsharp.git
This will make management of multiple forks and your own work easier over time.
We recommend the following commands to update your fork:
git checkout main
git clean -xdf
git fetch upstream
git rebase upstream/main
git push
Or more succinctly:
git checkout main && git clean -xdf && git fetch upstream && git rebase upstream/main && git push
This will update your fork with the latest from dotnet/fsharp on your machine and push those updates to your remote fork.
Install the latest released Visual Studio, as that is what the main branch's tools are synced with. Select the following workloads:
- .NET desktop development (also check F# desktop support, as this will install some legacy templates)
- Visual Studio extension development
You will also need the latest .NET 5 SDK installed from here.
Building is simple:
build.cmd
Desktop tests can be run with:
build.cmd -test -c Release
After you build the first time you can open and use this solution in Visual Studio:
.\VisualFSharp.sln
If you don't have everything installed yet, you'll get prompted by Visual Studio to install a few more things. This is because we use a .vsconfig file that specifies all our dependencies.
If you are just developing the core compiler and library then building FSharp.sln will be enough.
We recommend installing the latest released Visual Studio and using that if you are on Windows. However, if you prefer not to do that, you will need to install the following:
You'll need to pass an additional flag to the build script:
build.cmd -noVisualStudio
You can open FSharp.sln in your editor of choice.
For Linux/Mac:
./build.sh
Running tests:
./build.sh --test
You can then open FSharp.sln in your editor of choice.
You can find all test options as separate flags. For example build -testAll:
-testAll Run all tests
-testCambridge Run Cambridge tests
-testCompiler Run FSharpCompiler unit tests
-testCompilerService Run FSharpCompilerService unit tests
-testDesktop Run tests against full .NET Framework
-testCoreClr Run tests against CoreCLR
-testFSharpCore Run FSharpCore unit tests
-testFSharpQA Run F# Cambridge tests
-testScripting Run Scripting tests
-testVs Run F# editor unit tests
Running any of the above will build the latest changes and run tests against them.
If your changes involve modifying the list of language keywords in any way, (e.g. when implementing a new keyword), the XLF localization files need to be synced with the corresponding resx files. This can be done automatically by running
pushd src\fsharp\FSharp.Compiler.Service
msbuild FSharp.Compiler.Service.fsproj /t:UpdateXlf
popd
This only works on Windows/.NETStandard framework, so changing this from any other platform requires editing and syncing all of the XLF files manually.
As you would expect, doing this requires both Windows and Visual Studio are installed.
See (DEVGUIDE.md#Developing on Windows) for instructions to install what is needed; it's the same prerequisites.
First, ensure that VisualFSharpDebug is the startup project.
Then, use the f5 or ctrl+f5 keyboard shortcuts to test your tooling changes. The former will debug a new instance of Visual Studio. The latter will launch a new instance of Visual Studio, but with your changes installed.
Alternatively, you can do this entirely via the command line if you prefer that:
devenv.exe /rootsuffix RoslynDev
If you'd like to "run with your changes", you can produce a VSIX and install it into your current Visual Studio instance:
VSIXInstaller.exe /u:"VisualFSharp"
VSIXInstaller.exe artifacts\VSSetup\Release\VisualFSharpDebug.vsix
It's important to use Release if you want to see if your changes have had a noticeable performance impact.
Use the Debug configuration to test your changes locally. It is the default. Do not use the Release configuration! Local development and testing of Visual Studio tooling is not designed for the Release configuration.
You may run into an issue with a somewhat difficult or cryptic error message, like:
error VSSDK1077: Unable to locate the extensions directory. "ExternalSettingsManager::GetScopePaths failed to initialize PkgDefManager for C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\devenv.exe".
Or hard crash on launch ("Unknown Error").
To fix this, delete these folders:
%localappdata%\Microsoft\VisualStudio\<version>_(some number here)RoslynDev%localappdata%\Microsoft\VisualStudio\<version>_(some number here)
Where <version> corresponds to the latest Visual Studio version on your machine.
The primary technical guide to the core compiler code is The F# Compiler Technical Guide. Please read and contribute to that guide.
See the "Debugging The Compiler" section of this article for some examples.
If you are behind a proxy server, NuGet client tool must be configured to use it:
See the Nuget config file documention for use with a proxy server https://docs.microsoft.com/en-us/nuget/reference/nuget-config-file