In 2.2 tools packages, multitarget 2.2 and 2.1 so latest version is usable with LTS SDK

[dagood]

Problem

Summary from dotnet/source-build#926:

The source-build SDK product used by Red Hat doesn't include ASP.NET Core cli tools (e.g. dotnet-dev-certs). When the user tries to use the tool, they're prompted to run dotnet tool install --global dotnet-dev-certs. That works when the SDK they're using is the latest stable SDK available, like 2.2.101. However, it doesn't work in the 2.1.500 SDK with 2.1.6 Runtime anymore:

$ dotnet tool install -g dotnet-dev-certs
error NU1202:
Package dotnet-dev-certs 2.2.0 is not compatible with netcoreapp2.1 (.NETCoreApp,Version=v2.1) / any.
Package dotnet-dev-certs 2.2.0 supports: netcoreapp2.2 (.NETCoreApp,Version=v2.2) / any

The existence of the 2.2.0 tool package on the NuGet gallery prevents the desired, compatible dotnet-dev-certs 2.1.1 package from being found.

The workaround is to add --version '2.1.*' or a specific version to the dotnet tool install command.

Solution

If the 2.2.0 package also supported netcoreapp2.1, then the user would install 2.2.0 successfully and be on their way. The way to do this is through multitargeting:

-<TargetFramework>netcoreapp2.2<TargetFramework>
+<TargetFrameworks>netcoreapp2.1;netcoreapp2.2<TargetFrameworks>

Reasons this might not work well:

• To work effectively in the future, every tool package version train (2.2, 3.0, 3.1?, ...) needs to multitarget all previous frameworks. That way, 2.1 SDK will still be able to find a compatible tool when, say, 3.0.0 is the latest.
• If there are actual functional differences between the 2.1.* and 2.2.* tool packages, I can imagine that being difficult to maintain. I think 2.1 changes would need to be maintained in both the 2.1 ASP.NET branch as well as the 2.2 branch so 2.2 can target netcoreapp2.1.

Alternatives

There are other solutions described in dotnet/source-build#926 that are more palatable and wouldn't need any changes on your part. Multi-targeting is just one approach I think is worth asking about in case I've misjudged it. 😄

/cc @natemcmaster @omajid @wli3

[mkArtakMSFT]

Thanks for contacting us. We're closing this issue as there was no community involvement here for quite a while now.