Add better assembly resolve for PublishTrimmed build option for AspNet Core

[jeremielec]

Is your feature request related to a problem? Please describe.

A major feature of .Net core is now to allow project to be publish trimmed (Aka removing unused assembly) and self-contained.
This does not work fine with AspNet Core, as stated here, use reflexion.
Therefore used type in controllers are mostly stripped out (Like smtpclient). Occur if the type is created directly in controllers or injected via dependencies injection.

Describe the solution you'd like

Improve PublishTrimmed option for not remove directly used assembly by controllers.

Additional context

Attached sample project with a simple route /test

TrimProblemExample.zip

This work fine when lauched with visual studio.
This not work with bellow error when lauched with standalone publish with

dotnet publish WebApplication5.csproj --output out

(note that publish option are in the csproj)

Unhandled exception. System.TypeLoadException: Could not load type 'System.Net.Mail.SmtpClient' from assembly 'Microsoft.AspNetCore.Mvc.ViewFeatures, Version=3.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.

[mmarinchenko]

+1

dotnet publish generates .deps.json file wich contains dependencies section. In my case System.Resources.ResourceManager assembly was trimmed out from output directory while existing in dependencies section of .deps.json file.

I had to add the following to project configuration to solve this:

  <ItemGroup>
    <TrimmerRootAssembly Include="System.Resources.ResourceManager" />
  </ItemGroup>

Two different dependency resolvers in one command?

[romanryasne2]

Any updates?

[wtgodbe]

@javiercn @Pilchie thoughts on who should take a look at this?

[davidfowl]

Closing as part of #27384