NuGet friendly names -> framework names should be statically calculated

[davkean]

We want to use NuGet friendly names as part of the user-visible TFMs of the project file. Original proposal was to use a target to convert from them -> TFMs, however, that will cause no end of trouble for things that already expect TFMs to be static (common targets) and VS which will require a (slow) design-time build just to figure out what the real TFM is.

Instead we should see if we can come up with a mechanism where we can declare this statically use a series of properties + conditions and have it statically available.

[srivatsn]

@nguerrera - you'll need this for supporting cross-targeting

[nguerrera]

Perhaps we can generate the static logic rather than hand-authoring a copy of the mapping in msbuild xml.

[nguerrera]

Where is the source of truth for these mappings?

[eerhardt]

Where is the source of truth for these mappings?

The best thing I know of is in NuGet. See the following PR that added 'netcoreapp1.0'.

https://github.com/NuGet/NuGet.Client/pull/361/files

[nguerrera]

I have a strategy that can work for short TFMs of the form <name><version>, but not for PLIB profiles of the form <name1><version1>+...+<nameN><versionN>. To what extent do we need to support targeting these profiles with our sdk? Would it be acceptable if I assigned one canonical spelling to each PLIB profile and only recognized that exact spelling? i.e. no reordering of platforms or various other equivalences?

@davkean

[davkean]

I think project.json just pointed to the profiles themselves to build these, ie I don't think we need to support it - as long as there's a way to target just using the full name.

[abpiskunov]

sdk already references nuget assemblies, why not use Nuget API for all framework names manipulations?

[nguerrera]

Hmm, supporting both full names and short names complicates things, but I think I can manage it.

So, we support either "net45" or ".NETFramework,Version=v4.5", etc. for "netstandard" and a bunch more.

but if you want to target a portable profile you have to use the long form ".NETFramework,Version=v4.5,Profile=Profile1"?

[nguerrera]

@abpiskunov Because the goal here is to be able to get the target frameworks during static evaluation.

[nguerrera]

Does anyone have a pointer to a project.json using a PLIB profile?