`add package` command doesn't properly retain XML comments

[brettfo]

NuGet Product Used

dotnet.exe

Product Version

.NET SDK 9.0.204

Worked before?

No

Impact

It bothers me. A fix would be nice

Repro Steps & Context

Create a .csproj with the following contents:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" /><!-- some comment -->
  </ItemGroup>
</Project>

Run the following command:

dotnet add package Serilog --version 4.3.0

Result:

The trailing comment on the Newtonsoft.Json line is moved to the newly added package.

<ItemGroup>
  <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
  <PackageReference Include="Serilog" Version="4.3.0" /><!-- some comment -->
</ItemGroup>

Expected:

The trailing comment on the Newtonsoft.Json line should have stayed put.

<ItemGroup>
  <PackageReference Include="Newtonsoft.Json" Version="13.0.1" /><!-- some comment -->
  <PackageReference Include="Serilog" Version="4.3.0" />
</ItemGroup>

Verbose Logs

[zivkan]

I've been working on relevant code recently, so I'm fairly confident that NuGet's code that adds the package reference is here: https://github.com/NuGet/NuGet.Client/blob/a046e80d8df305f2b5ade060032fe0f5a1042256/src/NuGet.Core/NuGet.CommandLine.XPlat/Utility/MSBuildAPIUtility.cs#L426-L434

However, NuGet is just calling MSBuild APIs, in particular ProjectItemGroupElement.AddItem. So, unless NuGet stops and does our own XML parsing & writing just for this issue, I don't think it can be fixed without dotnet/msbuild making the change.

[jebriede]

I was able to repro the issue as described. The comment gets moved to the newly added package if the newly added package is inserted after the package reference with the inline comment.

[nkolev92]

Team Triage: As @zivkan suggested, this is an MSBuild API that we're calling.

We'll move the issue there.