Support building for multiple RIDs, similar to how TargetFrameworks works

Steps to reproduce

Have project file

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFrameworks>netcoreapp2.1;netcoreapp2.0</TargetFrameworks>
    <RuntimeIdentifiers>win;linux-x64</RuntimeIdentifiers>
  </PropertyGroup>
</Project>

run dotnet build

Expected behavior

Builds .dlls, that is the cross join between the RuntimeIdentifiers and TargetFrameworks

Actual behavior

Tries to build the any rid for each framework in TargetFrameworks but can’t because the any rid is unbuildable on this project.

Environment data

dotnet --info output:

.NET Core SDK (reflecting any global.json): Version: 2.1.302 Commit: 9048955601

Runtime Environment: OS Name: debian OS Version: 9 OS Platform: Linux RID: debian.9-x64 Base Path: /usr/share/dotnet/sdk/2.1.302/

Host (useful for support): Version: 2.1.2 Commit: 811c3ce6c0

.NET Core SDKs installed: 2.1.302 [/usr/share/dotnet/sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.All 2.1.2 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.1.2 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.1.2 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

@onovotny: I tried your MSBuild.Sdk.Extras version 1.6.30-preview and 1.7.1-preview; however while it can make a reference assembly just fine it doesn’t seem to convince dotnet build or dotnet pack to do the right thing with RuntimeIdentifiers. 1.6.40 seems to be brain-damaged and the builds bomb.

dotnet /usr/share/dotnet/sdk/2.1.302/MSBuild.dll doesn’t work either.

[caizixian]

The scenario could be interesting for how things will change in “.NET 5”…

No idea how/if TFMs are going to evolve but I could also easily see a world where we could do

<PropertyGroup>
  <TargetFramework>net5.0</TargetFramework>
  <RuntimeIdentifiers>iOS12.0-arm64;iOS12.0-x64;android-arm;android-arm64;android-x64</RuntimeIdentifiers>
</PropertyGroup>

or something similar instead of monoandroid60 and friends. (though I don’t think this would be RIDs)

This is a valid scenario.

I’d argue that on desktop platforms, it also makes sense to have, e.g. <RuntimeIdentifiers>osx-x64;linux-x64</RuntimeIdentifiers>, so that I can get multiple executables, one for each RID, with a single dotnet publish. Of course, I can run dotnet publish -r multiple times, but it’s more desirable to have it built into the build system.

[dasMulli]

The scenario could be interesting for how things will change in “.NET 5”…

No idea how/if TFMs are going to evolve but I could also easily see a world where we could do

<PropertyGroup>
  <TargetFramework>net5.0</TargetFramework>
  <RuntimeIdentifiers>iOS12.0-arm64;iOS12.0-x64;android-arm;android-arm64;android-x64</RuntimeIdentifiers>
</PropertyGroup>

or something similar instead of monoandroid60 and friends. (though I don’t think this would be RIDs)