├── .gitignore
├── ConsoleApp
    ├── Program.cs
    └── ConsoleApp.csproj
├── StandaloneLibrary
    ├── Calculator.cs
    └── StandaloneLibrary.csproj
├── nuget.config
├── MinimalDotNetWasmNativeAOT.sln
├── README.md
└── Directory.Build.targets


/.gitignore:
--------------------------------------------------------------------------------
1 | .vs/
2 | bin/
3 | obj/
4 | 


--------------------------------------------------------------------------------
/ConsoleApp/Program.cs:
--------------------------------------------------------------------------------
1 | // See https://aka.ms/new-console-template for more information
2 | Console.WriteLine("Hello, World!");
3 | 


--------------------------------------------------------------------------------
/StandaloneLibrary/Calculator.cs:
--------------------------------------------------------------------------------
 1 | using System.Runtime.InteropServices;
 2 | 
 3 | namespace MyApp;
 4 | 
 5 | public static class Calculator
 6 | {
 7 |     [UnmanagedCallersOnly(EntryPoint = "add")]
 8 |     public static int Add(int a, int b) => a + b;
 9 |     
10 |     [UnmanagedCallersOnly(EntryPoint = "subtract")]
11 |     public static int Subtract(int a, int b) => a - b;
12 | }
13 | 


--------------------------------------------------------------------------------
/nuget.config:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="utf-8"?>
 2 | <configuration>
 3 |   <packageSources>
 4 |     <!--To inherit the global NuGet package sources remove the <clear/> line below -->
 5 |     <clear />
 6 |     <add key="dotnet8" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet8/nuget/v3/index.json" />
 7 |     <add key="dotnet-experimental" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-experimental/nuget/v3/index.json" />
 8 |     <add key="nuget" value="https://api.nuget.org/v3/index.json" />
 9 |   </packageSources>
10 | </configuration>
11 | 


--------------------------------------------------------------------------------
/ConsoleApp/ConsoleApp.csproj:
--------------------------------------------------------------------------------
 1 | <Project Sdk="Microsoft.NET.Sdk">
 2 | 
 3 |   <PropertyGroup>
 4 |     <OutputType>exe</OutputType>
 5 |     <TargetFramework>net8.0</TargetFramework>
 6 |     <ImplicitUsings>enable</ImplicitUsings>
 7 |     <Nullable>enable</Nullable>
 8 |     <PublishTrimmed>true</PublishTrimmed>
 9 |     <InvariantGlobalization>true</InvariantGlobalization>
10 |     <UseAppHost>false</UseAppHost>
11 |     <SelfContained>true</SelfContained>
12 |     <RuntimeIdentifier>wasi-wasm</RuntimeIdentifier>
13 |     <MSBuildEnableWorkloadResolver>false</MSBuildEnableWorkloadResolver>
14 |   </PropertyGroup>
15 | 
16 |   <ItemGroup>
17 |     <PackageReference Include="Microsoft.DotNet.ILCompiler.LLVM" Version="8.0.0-preview.7.23503.1" />
18 |     <PackageReference Include="runtime.win-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="8.0.0-preview.7.23503.1" />
19 |   </ItemGroup>
20 | 
21 |   <!-- For simplicity, publish on build -->
22 |   <Target Name="RunAotBuild" AfterTargets="Build" DependsOnTargets="Publish" />
23 | 
24 | </Project>
25 | 


--------------------------------------------------------------------------------
/StandaloneLibrary/StandaloneLibrary.csproj:
--------------------------------------------------------------------------------
 1 | <Project Sdk="Microsoft.NET.Sdk">
 2 | 
 3 |   <PropertyGroup>
 4 |     <OutputType>Library</OutputType>
 5 |     <TargetFramework>net8.0</TargetFramework>
 6 |     <ImplicitUsings>enable</ImplicitUsings>
 7 |     <Nullable>enable</Nullable>
 8 |     <PublishTrimmed>true</PublishTrimmed>
 9 |     <InvariantGlobalization>true</InvariantGlobalization>
10 |     <UseAppHost>false</UseAppHost>
11 |     <SelfContained>true</SelfContained>
12 |     <RuntimeIdentifier>wasi-wasm</RuntimeIdentifier>
13 |     <MSBuildEnableWorkloadResolver>false</MSBuildEnableWorkloadResolver>
14 |   </PropertyGroup>
15 | 
16 |   <ItemGroup>
17 |     <PackageReference Include="Microsoft.DotNet.ILCompiler.LLVM" Version="8.0.0-preview.7.23503.1" />
18 |     <PackageReference Include="runtime.win-x64.Microsoft.DotNet.ILCompiler.LLVM" Version="8.0.0-preview.7.23503.1" />
19 |   </ItemGroup>
20 | 
21 |   <!-- For simplicity, publish on build -->
22 |   <Target Name="RunAotBuild" AfterTargets="Build" DependsOnTargets="Publish" />
23 | 
24 | </Project>
25 | 


--------------------------------------------------------------------------------
/MinimalDotNetWasmNativeAOT.sln:
--------------------------------------------------------------------------------
 1 | 
 2 | Microsoft Visual Studio Solution File, Format Version 12.00
 3 | # Visual Studio Version 17
 4 | VisualStudioVersion = 17.5.002.0
 5 | MinimumVisualStudioVersion = 10.0.40219.1
 6 | Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ConsoleApp", "ConsoleApp\ConsoleApp.csproj", "{5A9121E0-8590-4D2F-98FB-A2DBB2B7260A}"
 7 | EndProject
 8 | Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "StandaloneLibrary", "StandaloneLibrary\StandaloneLibrary.csproj", "{441CB253-0F77-44F2-81F4-C24864CCE521}"
 9 | EndProject
10 | Global
11 | 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
12 | 		Debug|Any CPU = Debug|Any CPU
13 | 		Release|Any CPU = Release|Any CPU
14 | 	EndGlobalSection
15 | 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
16 | 		{5A9121E0-8590-4D2F-98FB-A2DBB2B7260A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
17 | 		{5A9121E0-8590-4D2F-98FB-A2DBB2B7260A}.Debug|Any CPU.Build.0 = Debug|Any CPU
18 | 		{5A9121E0-8590-4D2F-98FB-A2DBB2B7260A}.Release|Any CPU.ActiveCfg = Release|Any CPU
19 | 		{5A9121E0-8590-4D2F-98FB-A2DBB2B7260A}.Release|Any CPU.Build.0 = Release|Any CPU
20 | 		{441CB253-0F77-44F2-81F4-C24864CCE521}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
21 | 		{441CB253-0F77-44F2-81F4-C24864CCE521}.Debug|Any CPU.Build.0 = Debug|Any CPU
22 | 		{441CB253-0F77-44F2-81F4-C24864CCE521}.Release|Any CPU.ActiveCfg = Release|Any CPU
23 | 		{441CB253-0F77-44F2-81F4-C24864CCE521}.Release|Any CPU.Build.0 = Release|Any CPU
24 | 	EndGlobalSection
25 | 	GlobalSection(SolutionProperties) = preSolution
26 | 		HideSolutionNode = FALSE
27 | 	EndGlobalSection
28 | 	GlobalSection(ExtensibilityGlobals) = postSolution
29 | 		SolutionGuid = {BA44930B-C0E3-41DC-B0F6-3CCFE423B3DC}
30 | 	EndGlobalSection
31 | EndGlobal
32 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | # Minimal .NET -> WebAssembly via NativeAOT-LLVM
 2 | 
 3 | This repo contains two examples.
 4 | 
 5 | They are minimal in the sense of doing the smallest amount of stuff in the source code. However they are **not** minimal in terms of size - various things could be done to reduce the output size dramatically, such as stripping debug info or running `wasm-opt`.
 6 | 
 7 | ## Prerequisites
 8 | 
 9 |  * .NET 8 SDK
10 |  * To run the output on the command line, get [wasmtime](https://wasmtime.dev/) and put it on your PATH
11 | 
12 | ## ConsoleApp
13 | 
14 | The default "Hello World" app
15 | 
16 | To build:
17 | 
18 |  * `cd ConsoleApp`
19 |  * `dotnet build` (note: takes a few mins on the first run to acquire the SDKs, but is fast after)
20 |  * You now have `bin/Debug/net8.0/wasi-wasm/publish/ConsoleApp.wasm`
21 | 
22 | To run:
23 | 
24 |  * `wasmtime bin/Debug/net8.0/wasi-wasm/publish/ConsoleApp.wasm`
25 | 
26 | ## StandaloneLibrary
27 | 
28 | This produces a wasm module with an export called `add` you can invoke from some host environment.
29 | 
30 | To build:
31 | 
32 |  * `cd StandaloneLibrary`
33 |  * `dotnet build`
34 |  * You now have `bin/Debug/net8.0/wasi-wasm/publish/StandaloneLibrary.wasm`
35 |  
36 | Note that this is a "reactor" module, i.e., one with imports and exports but no entrypoint. So to run code from it, you have to call a named export and pass whatever parameters it wants, e.g., to run on the CLI:
37 | 
38 |  * `wasmtime bin/Debug/net8.0/wasi-wasm/publish/StandaloneLibrary.wasm --invoke add 123 456`
39 |  * `wasmtime bin/Debug/net8.0/wasi-wasm/publish/StandaloneLibrary.wasm --invoke subtract 123 456`
40 | 
41 | ... but more commonly, reactor modules are consumed by some hosting environment such as a web server that makes calls to your module's exports.
42 | 


--------------------------------------------------------------------------------
/Directory.Build.targets:
--------------------------------------------------------------------------------
 1 | <Project>
 2 | 
 3 |     <!--
 4 |     MSBuild stuff to acquire the necessary SDKs (WASI SDK and Emscripten) automatically. It will take a few mins on the
 5 |     first build on a given machine, but after that should no-op.
 6 |     -->
 7 | 
 8 |     <PropertyGroup>
 9 |         <!-- Keep this block all in sync manually, since URLs can be arbitrary -->
10 |         <WasiSdkVersion>20.0</WasiSdkVersion>
11 |         <WasiSdkUrl Condition="$([MSBuild]::IsOSPlatform('Windows'))">https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-20/wasi-sdk-20.0.m-mingw.tar.gz</WasiSdkUrl>
12 |         <WasiSdkUrl Condition="$([MSBuild]::IsOSPlatform('Linux'))">https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-20/wasi-sdk-20.0-linux.tar.gz</WasiSdkUrl>
13 |         <WasiSdkUrl Condition="$([MSBuild]::IsOSPlatform('OSX'))">https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-20/wasi-sdk-20.0-macos.tar.gz</WasiSdkUrl>		
14 |         <WasiSdkRoot>$([System.IO.Path]::Combine("$([System.Environment]::GetFolderPath(SpecialFolder.UserProfile))", ".wasi-sdk", "wasi-sdk-$(WasiSdkVersion)"))</WasiSdkRoot>
15 | 
16 |         <EmSdkVersion>3.1.23</EmSdkVersion>
17 |         <EmSdkUrl>https://github.com/emscripten-core/emsdk/archive/refs/tags/$(EmSdkVersion).zip</EmSdkUrl>
18 |         <EmscriptenRoot>$([System.IO.Path]::Combine("$([System.Environment]::GetFolderPath(SpecialFolder.UserProfile))", ".emsdk", "emsdk-$(EmSdkVersion)"))</EmscriptenRoot>
19 | 
20 |         <CopyWasmToOutputDependsOn>
21 |             $(CopyWasmToOutputDependsOn);
22 |             ObtainWasiSdk;
23 |             PrepareBuildWasmInputs;
24 |             BuildWasm;
25 |         </CopyWasmToOutputDependsOn>
26 |     </PropertyGroup>
27 | 
28 |     <Target Name="PrepareWasmSdks" BeforeTargets="CheckWasmSdks" DependsOnTargets="ObtainWasiSdk; ObtainEmscripten">
29 |         <PropertyGroup>
30 |             <EmSdk>$(EmscriptenRoot)</EmSdk>
31 |             <WASI_SDK_PATH>$(WasiSdkRoot)</WASI_SDK_PATH>
32 |         </PropertyGroup>
33 |     </Target>
34 | 
35 |     <Target Name="ObtainEmscripten" Condition="'$(EMSDK)' == '' AND !(Exists($(EmscriptenRoot)))">
36 |         <PropertyGroup>
37 |             <EmSdkDownloadTempDir>$(IntermediateOutputPath)\emsdk-temp</EmSdkDownloadTempDir>
38 |         </PropertyGroup>
39 | 
40 |         <MakeDir Directories="$(EmSdkDownloadTempDir)" />
41 |         <DownloadFile
42 |             SourceUrl="$(EmSdkUrl)"
43 |             DestinationFolder="$(EmSdkDownloadTempDir)">
44 |             <Output TaskParameter="DownloadedFile" ItemName="EmSdkDownloadTempFile" />
45 |         </DownloadFile>
46 | 
47 |         <!-- Windows 10+ has tar built in, so this should work cross-platform -->
48 |         <Message Importance="high" Text="Extracting @(EmSdkDownloadTempFile) to $(EmscriptenRoot)..." />
49 |         <MakeDir Directories="$(EmscriptenRoot)" />
50 |         <Exec Command="tar -xf &quot;@(EmSdkDownloadTempFile)&quot; -C . --strip-components=1" WorkingDirectory="$(EmscriptenRoot)" />
51 |         <RemoveDir Directories="$(EmSdkDownloadTempDir)" />
52 | 
53 |         <Exec Command="emsdk install $(EmSdkVersion)" WorkingDirectory="$(EmscriptenRoot)" />
54 |         <Exec Command="emsdk activate $(EmSdkVersion)" WorkingDirectory="$(EmscriptenRoot)" />
55 |     </Target>
56 | 
57 |     <Target Name="ObtainWasiSdk" Condition="!(Exists($(WasiSdkRoot)))">
58 |         <PropertyGroup>
59 |             <WasiSdkDownloadTempDir>$(IntermediateOutputPath)\wasi-sdk-temp</WasiSdkDownloadTempDir>
60 |         </PropertyGroup>
61 | 
62 |         <MakeDir Directories="$(WasiSdkDownloadTempDir)" />
63 |         <DownloadFile
64 |             SourceUrl="$(WasiSdkUrl)"
65 |             DestinationFolder="$(WasiSdkDownloadTempDir)">
66 |             <Output TaskParameter="DownloadedFile" ItemName="WasiSdkDownloadTempFile" />
67 |         </DownloadFile>
68 | 
69 |         <!-- Windows 10+ has tar built in, so this should work cross-platform -->
70 |         <Message Importance="high" Text="Extracting @(WasiSdkDownloadTempFile) to $(WasiSdkRoot)..." />
71 |         <MakeDir Directories="$(WasiSdkRoot)" />
72 |         <Exec Command="tar -xf &quot;@(WasiSdkDownloadTempFile)&quot; -C . --strip-components=1" WorkingDirectory="$(WasiSdkRoot)" />
73 |         <RemoveDir Directories="$(WasiSdkDownloadTempDir)" />
74 |     </Target>
75 | </Project>
76 | 


--------------------------------------------------------------------------------