commandlineparser / commandlineparser/commandline

.NET 7 (RC1) trimming results in error

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#848 16 comments 7 reactions 0 assignees View on GitHub
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C#
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Description

I've just upgraded my project to .NET 7 and seen that it results in an error (when running):

```
Error setting value to option 'u, url': Check if Option or Value attribute values are set properly for the given type.
Error setting value to option 't, threads': Check if Option or Value attribute values are set properly for the given type.
etc..
```

https://github.com/KoalaBear84/OpenDirectoryDownloader/

If I build it with the following it fails (when running):
```
dotnet publish OpenDirectoryDownloader --configuration Release --framework net7.0 --runtime win-x64 -p:PublishTrimmed=true
```

If I remove the `-p:PublishTrimmed=true` it works. This tells me it could be because of the trimming that will trim something that is important for this library.

Also tried with `-p:TrimMode=Link` and `-p:TrimMode=CopyUsed`, but it doesn't make a difference, but found out that `-p:TrimMode=partial` (Only worked with a lowercase p here) does, as it restores the behaviour of .NET 6.

https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/trimming-options?pivots=dotnet-7-0#trimming-granularity

Maybe this can be resolved at the library side, but I don't have experience with that.
https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/prepare-libraries-for-trimming

It would be nice if it can be solved, as more users will try/upgrade to .NET 7. Until then this issue will be helpful for everyone looking for a quick workaround.

Contributor guide

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Research direction

Reproduce the failure with the provided dotnet publish command using .NET 7, then compare it with trimming disabled and TrimMode=partial. Read the linked trimming guidance and inspect how the library handles the options that produce errors. Done means trimmed publishing runs without the reported option-setting errors while preserving normal command-line behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp
Domain
cli
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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