Update target framework version in toolsetinfo for NET 8.

[nagilson]

It would be ideal if this could be done automatically, though per Marc it could make the migration to 9 harder so probably not.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[marcpopMSFT]

You may want nexttargetframework to stay as 8.0. Jason added that for the transition from 7 to 8.0 as we had some tests that required 7 still and some that required 8 already. I don't think those tests will work targeting 9. The alternative is to move all tests that use next target framework currently back to current with this PR.

I like that alternative better.

[nagilson]

@marcpopMSFT Pretty sure that's already been done, there are no references to either of the nextTFM properties.

[dsplaisted]

I don't think that "Find all references" search is working. I see references still here:

sdk/src/Tests/Microsoft.NET.Build.Tests/GivenThatWeWantToControlGeneratedAssemblyInfo.cs

Lines 373 to 375 in 5a5e336

	[InlineData(true, true, ToolsetInfo.NextTargetFramework)]
	[InlineData(true, false, ToolsetInfo.NextTargetFramework)]
	[InlineData(false, false, ToolsetInfo.NextTargetFramework)]

sdk/src/Tests/Microsoft.NET.Publish.Tests/PublishTestUtils.cs

Line 20 in 5a5e336

new object[] { ToolsetInfo.NextTargetFramework }

[v-wuzhai]

The NextTargetFramework constant is also used in #29158.

[nagilson]

~~ @dotnet/templating-engine-maintainers PTAL at the failure:
Microsoft.DotNet.Cli.New.IntegrationTests.CommonTemplatesTests.FeaturesSupport(name: \"console\", buildPass: True, framework: \"net7.0\", langVersion: null, langVersionUnsupported: False, language: null, supportsNullable: True, supportsTopLevel: True, forceDisableTopLevel: False, supportsImplicitUsings: True, supportsFileScopedNs: True) with the new ToolsetInfo.CurrentTargetFramework.

https://dev.azure.com/dnceng-public/public/_build/results?buildId=110027&view=ms.vss-test-web.build-test-results-tab
~~

JK it's been fixed.

[nagilson]

@dotnet/dotnet-cli PTAL

[baronfel]

I'm glad that we caught some build-logic updates (warning levels) with this bump :) How concerned should I be that it looks like we're losing a lot of coverage on net7.0 TFMs on tests?

[nagilson]

I am not too concerned since they are still running in the 7x branches and theoretically any gap in 8 and 7 should be specifically tested with 7 and 8. (I'm not saying they are, but stylistically it would be the correct thing to do and it's what I've been doing for 8.0 breaking changes.)

[baronfel]

@nagilson impeccable response, you are of course correct on all counts. Thank you :)

[nagilson]

Lol! I have gotten better at covering my bases.

[marcpopMSFT]

+1 to what Noah said. We should probably identify a specific set of tests that target all supported runtimes as a baseline but everything else we should roll forward each release.