GenerateToolsSettingsFile causes incremental build issues

[alexrp]

The GenerateToolsSettingsFile task unconditionally writes DotnetToolSettings.xml on every build. This causes issues with incremental builds; specifically, dotnet pack will always generate a fresh package because the GenerateNuspec target considers this file as one of its inputs.

I'm not sure what the proper fix is here. Maybe GenerateToolsSettingsFile should compare the generated document with the existing file and only write the document if it's different?

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

[martincostello]

I'm running into this quite frequently now since updating to the .NET 9.0.200 SDK but only on Windows (this build is up to 16 attempts now).

[baronfel]

As of #32798 this target should be properly incremental - however as @martincostello is finding it's generating the tool command xml file per-TFM, while that file is generated to a TFM-oblivious location. We either need to do the safe thing and generate separate, per-TFM XML files or figure out another mechanism to ensure that the Target's only called once (or at least called with enough staggering so that projects building on different nodes can see that the cache has been populated.

[baronfel]

@martincostello consider instead of multi-targeting your tool, setting RollFoward of Major or LatestMajor so that your tool can run on 9.x runtimes without requiring you to multitarget.

[martincostello]

For now I've just done this: <BuildInParallel Condition="$([MSBuild]::IsOSPlatform('Windows'))">false</BuildInParallel>