msbuild custom task and runtime reflection

- 1 minutes read - 186 words

Most information about custom task of msbuild are quite basic, it will get complicated when it is involved reflection. I tried several ways according searching results and answers from chatgpt: reflection, assemblyLoadContext and mono cecil. The most promising one is mono.cecil.

I tried directly loading assemblies and via AssemblyLoadContext. They all failed to load some microsoft assemblies. It looks awkward even I can change my build scripts to copy those assemblies. Thought of several discussion threads and several open source libraries mentioned in the thread, They all adopt other ways to do that. I only found mono.cecil has a business friendly license term (MIT).

During testing my custom task, the following two commands are helpful to get the logs.

dotnet build -v:n
dotnet build -v:d

Message task is helpful to show properties in logs.

  <Target Name="Test" Outputs="$(RootFolder)\$(OutputFolder)\metadata\*.json" AfterTargets="Build">
    <Message Importance="High" Text="+++ Justin Dearing +++" />
    <!--Calling our custom task-->
    <ExportConformanceResource
			InputAssembly="$(TargetPath)"
			OutputPath="$(RootFolder)\$(OutputFolder)" />
  </Target>

Another way to develop and debug fastly:

  1. Add System.Diagnostics.Debugger.Launch() in code.

  2. Build debug version, pack, add to local feed, and use that package

  3. Copy any changes (ddl, props, targets) to %userprofile%/packages/[your package]/[versionid]

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