dotnet build doesn't write runtime properties to .runtimeconfig.json on .NET 2.1

Using .NET Core 2.1

mkdir repro
cd repro
dotnet new console

Edit repro.csproj to add ServerGarbageCollection property:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.1</TargetFramework>
    <ServerGarbageCollection>true</ServerGarbageCollection>
  </PropertyGroup>
</Project>

dotnet build

Open the repro.runtimeconfig.json:

{
  "runtimeOptions": {
    "tfm": "netcoreapp2.1",
    "framework": {
      "name": "Microsoft.NETCore.App",
      "version": "2.1.0"
    }
  }
}

It should have the System.GC.Server property:

    "configProperties": {
      "System.GC.Server": true
    }

Running:

dotnet publish

Will produce the correct .runtimeconfig.json into the publish folder.

[vitek-karas]

Sorry - I can’t repro it either now. I know I tried it several times yesterday, but now on the same machine it works just fine. I guess I must have run into the incremental build issue without realizing it…

Sorry again for the confusion.

[vitek-karas]

There are two separate issues here:

The one tracked by this bug, which is about the fact that runtime properties are not written to .runtimeconfig.json on .NET Core 2.1 (and probably 2.2). It works on 3.0. This is true even for clean/build. Basically this issue is about the discussion whether we can fix it for 2.* apps in some way.

The other problem is that changing settings which affect .runtimeconfig.json are not triggering rebuild of that file during incremental dotnet build. That issue is tracked by #2787 - or it seems so.