ConfigurationBinder.Bind and ConfigurationBinder.Get trimming warning

[eduherminio]

Given a project with :

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <PublishTrimmed>true</PublishTrimmed>
    <TrimMode>link</TrimMode>
  </PropertyGroup>

public class GeneralSettings {}

var settingsInstance = new GeneralSettings();
var config = new ConfigurationBuilder().Build();

When I use ConfigurationBinder.Bind

config.GetRequiredSection(nameof(EngineSettings)).Bind(settingsInstance);

I get the following warning:

warning IL2026:
Using method 'Microsoft.Extensions.Configuration.ConfigurationBinder.Bind(Microsoft.Extensions.Configuration.IConfiguration, object)' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Cannot statically analyze the type of instance so its members may be trimmed.

If I use ConfigurationBuilder.Get I also get a the same one:

settingsInstance = config.GetRequiredSection(nameof(GeneralSettings)).Get<GeneralSettings>();

Using method 'Microsoft.Extensions.Configuration.ConfigurationBinder.Get<Lynx.GameParameters>(Microsoft.Extensions.Configuration.IConfiguration)' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. In case the type is non-primitive, the trimmer cannot statically analyze the object's type so its members may be trimmed.

In both cases the code works after the trimming.

Should I suppress the warning?
Should I 'customize' the trimming?

I've read Customizing Trimming in .NET 5, but I'm unsure what's the best way to proceed for these specific methods.

[davidfowl]

These methods aren't trimming friendly. The linker can't tell what properties it should keep when you use these methods. Your options are:

• Bind the value manually (don't use these methods)
• The containing methods can declare what properties of GeneralSettings are used (using the dynamic dependency annotation)
• You can use the xml file to customize the linking process to preserve GeneralSettings properties.

[johnwc]

We're working on a source generator for configuration binding. Until then, manually binding really means manually binding each property by hand.

Or we can safely suppress the warning for now?

[colejohnson66]

@johnwc It is generally not safe to silence trim warnings.

[johnwc]

@colejohnson66 yes, I am aware of that and follow that rule. But, @davidfowl stated previously to silence it and I wanted to validate from him that it is ok to do such a thing.

[ThaDaVos]

Any update on the source generators?

[jasper-d]

Any update on the source generators?

It is part of .NET 8 but you'll need to enable it explicitly.

https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-8/runtime#configuration-binding-source-generator