Failure to preserve types enhancements #34734

guardrex · 2025-02-13T17:47:53Z

Pavel ... Could you take a look at this one?

Two of the approaches work as I describe.

One approach, the Root Descriptor approach, I can't get to work using several permutations of assembly, type, and method ... assembly only ... assembly and method only ... or all three. If it won't be easy to figure out why this approach isn't working, should we merge with just the [DynamicDependency] attribute approach and the custom type approach? If so, I'll clip the Root Descriptor approach out of this, and I'll make a tracking item entry to try again to cover it some other time.

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pavelsavara · 2025-02-17T10:10:04Z

You can find many examples of ILLink.Descriptors.xml in the runtime repo.
It may make sense to have full path via $(MSBuildThisFileDirectory) in the <TrimmerRootDescriptor Include="$(MSBuildThisFileDirectory)ILLink.Descriptors.xml" />

To see if your file was noticed or not, you can make it invalid xml and you should get fail. If nothing happened, somehow your TrimmerRootDescriptor didn' work.

I don't know if TrimmerRootDescriptor in MSbuild also works well for library projects and transitive dependencies of the trimmed app. Worth exploring.

Trimmer team prefers attributes over XML, because they don't have those problems.

The last option of using custom type instead is probably poor workaround, do we know why we say that ?
It would only work if the type was in assembly which doesn't have trimming enabled, which I guess is a (bad) default for app assemblies.
If we really want to propose that, I would treat it as very last resort.

guardrex · 2025-02-18T13:16:11Z

@pavelsavara ... No luck here this morning.

Let's take these one at a time ...

Breaking the XML

The first thing is breaking the XML to get an error to know if the file is being found. I took the opening <linker> tag out of the file; and either with or without $(MSBuildThisFileDirectory), I don't see an error anywhere at compile time or runtime. The app publishes normally AFAICT. Where would the error appear?

Method signature

I'm not sure what it should be. Nothing I've tried has worked. I'll leave it on the PR for now as ...

<method signature="System.Void .ctor(System.String,System.String)" />

... and that might be incorrect. However, we don't even know if my descriptor file is being picked up yet. If not, then all of my testing on method sigs was a waste of time.

Custom type

The last option of using custom type instead is probably poor workaround, do we know why we say that ?

It came from Javier here ...

dotnet/aspnetcore#52947 (comment)

I'm going to update that section to say that it will work but that we don't recommend the approach.

pavelsavara · 2025-02-18T14:19:30Z

I don't see an error anywhere at compile time

It means it's not being noticed by the msbuild scripts.

Do you have it in <ItemGroup> </ItemGroup> ?

guardrex · 2025-02-18T14:20:48Z

I do ...

<ItemGroup>
  <TrimmerRootDescriptor Include="$(MSBuildThisFileDirectory)ILLink.Descriptors.xml" />
</ItemGroup>

guardrex · 2025-02-18T14:21:21Z

... with a broken file ...

  <assembly fullname="System.Runtime">
    <type fullname="System.Collections.Generic.KeyValuePair">
      <method signature="System.Void .ctor(System.String,System.String)" />
    </type>
  </assembly>
</linker>

... and when I publish, I have my publish profile set up to delete all files before publishing ...

If you want, I can put the project up in a GH repo.

pavelsavara · 2025-02-18T14:36:27Z

If you want, I can put the project up in a GH repo.

yes

guardrex · 2025-02-18T14:57:23Z

🐀🍔 Roasted Rat Burgers! 🐀🍔

Ok ... I just made a major discovery here. The project that I'm using is a per-component BWA. I had the descriptor file set up in the server project 🙈 and just discovered that it has to be in the .Client project.

Let me try again now that I know what I was doing wrong. I'll get back to you in a bit .....................

guardrex · 2025-02-18T14:59:15Z

Yeah ... that seems ok now. I did get the broken XML file warning, fixed the file, and now it seems to be picking it up.

Next quesiton tho ... what is the correct method signature for the KeyValuePair example to make it work?

It isn't ...

<method signature="System.Void .ctor(System.String,System.String)" />

💥

crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: ConstructorContainsNullParameterNames, System.Collections.Generic.KeyValuePair2[System.String,System.String]
System.NotSupportedException: ConstructorContainsNullParameterNames, System.Collections.Generic.KeyValuePair2[System.String,System.String]

... and not ...

<method signature="System.Void .ctor(TKey,TValue)" />

I can keep trying with brute force, but I'll wait for you to advise me the format of the signature for this.

pavelsavara · 2025-02-18T15:07:49Z

    <type fullname="System.Collections.Generic.KeyValuePair`2">
        <method signature="System.Void .ctor()" />
        <method signature="System.Void .ctor(System.String,System.String)" />
    </type>

Try which of them works, with or without params.

guardrex · 2025-02-18T15:11:42Z

They both fail with ...

ILLink.Descriptors.xml(4,8): Warning IL2009: Could not find method 'System.Void .ctor()' on type 'System.Collections.Generic.KeyValuePair<TKey,TValue>'.

ILLink.Descriptors.xml(5,8): Warning IL2009: Could not find method 'System.Void .ctor(System.String,System.String)' on type 'System.Collections.Generic.KeyValuePair<TKey,TValue>'.

pavelsavara · 2025-02-18T15:14:59Z

<method signature="System.Void .ctor(TKey,TValue)" /> ?

guardrex · 2025-02-18T15:17:47Z

The error during build went away, but the component is still throwing ......

crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: ConstructorContainsNullParameterNames, System.Collections.Generic.KeyValuePair2[System.String,System.String] System.NotSupportedException: ConstructorContainsNullParameterNames, System.Collections.Generic.KeyValuePair2[System.String,System.String]

pavelsavara · 2025-02-18T15:32:57Z

ConstructorContainsNullParameterNames

Why this is not working for you dotnet/runtime#102850
You are testing Net9 right ?

Maybe for Net8 and older @javiercn 's advice to use custom type is necessary fallback.

guardrex · 2025-02-18T15:35:37Z

Correct ... 9.0 app.

Do you want me to place the custom type back for <=8.0, or should this only have the [DynamicDependency] attribute approach for <=8.0?

guardrex · 2025-02-18T15:38:27Z

... so the fix is really going to be for .NET 10? ... I say so because the original issue is still open at ...

dotnet/aspnetcore#52947

... marked for .NET 10 and apparently covered by ...

dotnet/runtime#112216

If so, then we only have the [DynamicDependency] attribute approach and the custom type approach, and those two are valid for all versions. Then, we'll add this file descriptor approach at .NET 10's release (but it will work back to 8.0)?

This is very confusing! 😆

pavelsavara · 2025-02-18T15:44:26Z

Now I understand more: There are 2 levels to this problem

trimming the class/constructor
trimming the parameter names

In dotnet/runtime#112216 Larry suggest to make trimming much less aggressive, which will probably solve both issues. This is only for Net 8

I believe that after dotnet/runtime#102850 rooting the ctor 1) will also keep names 2)
This was merged in May, so I assume it landed in Net9.
If it's still broken, we need to open issue and provide clear steps to reproduce.

guardrex · 2025-02-18T15:47:59Z

I see.

~~Should I put my test app up just so that you can check and make sure I have everything correct?~~

I just put it up here ....

https://github.com/guardrex/BlazorTrimmerTesting

You say a new issue, but dotnet/aspnetcore#52947 is still open. Seems like they just wouldn't close that one and keep working on it.

UPDATE: I added a comment to the open issue.

guardrex · 2025-02-18T16:11:54Z

I've noted in the article text using my tracking moniker ("UPDATE 10.0") to circle back around later for more work to bring back the file descriptor approach and drop the custom types approach.

pavelsavara · 2025-02-18T16:44:23Z

Does the DynamicDependency solve the ConstructorContainsNullParameterNames issue ?

guardrex · 2025-02-18T16:45:01Z

Yes, it does.

aspnetcore/blazor/host-and-deploy/configure-trimmer.md

guardrex added 2 commits February 13, 2025 12:45

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guardrex mentioned this pull request Feb 18, 2025

A published blazor wasm app throws a serialization error "Unhandled exception rendering component: ConstructorContainsNullParameterNames" dotnet/aspnetcore#52947

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Failure to preserve types enhancements #34734

Failure to preserve types enhancements #34734

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