[Vcxproj] Improve NuGet handling in packages.config mode & add necessary logic for package reference mode

[zyzyz]

1. Improve .targets import logic when using NuGet packages.config mode

Old Behaviour: /build/native/*.targets and /build/*.targets are both imported.

Problem: in common, /build/native/*.targets for C++ project is firstly chosen if presented, old logic will make /build/*.targets also be imported, and in before of /build/native/*.targets, causing troubles.
e.g. Microsoft.WindowsAppSDK

Current Behaviour: /build/native/*.targets import is made before /build/*.targets , it will check if /build/native/*.targets
is not presented, then do the /build/*.targets import.

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2. Add support codes for NuGet package reference mode in .vcxproj

The current NuGet support for C++ project is incomplete.

• .props file import is not supported.
• lack methods to determine if .targets and .props files are initially presented in order to generate correct error check.
• Irregular path to .targets and .props files are not supported.
  • Like the problem discussed below (yet providing a configurable custom path is not a good solution)
    [Vcxproj] Support explicit path to NuGet .targets, and clean up existing packages.config if no longer needed #390
• All other downsides of packages.config mode (cannot restore dependencies, etc.)

here and NuGet/NuGet.Client#3145 have shown the way to force package reference mode for .vcxproj.
To achieve this in Sharpmake, it requires

1. A custom configuration of Directory.Build.props
2. <PackageReference> element generation support inside Sharpmake

This PR contains the 2. part.

I haven't figure out the best way to automatically handle 1., but since Directory.Build.props is originally a thing that users manually add to their projects, so it should be no harm to let them also add that custom configuration manually (for now?)

P.S. the default NuGet mode for C++ project still keeps as packages.config.

[jspelletier]

Hi
We've started to check this PR. We ran regression tests on our big engines and it doesn't change anything(we don't use the features that this PR changes).

The next step is we need some samples using this if you ever want this to land eventually.

Thanks.

[jspelletier]

It looks like you need to update some samples reference files(see CI failure)

[zyzyz]

Hi,
I have updated the reference files in sample PackageReferences, and add a new sample CPPForcePackageReference.

Run .\RunSample.ps1 CPPForcePackageReference -framework "net6.0" -VsVersionSuffix "vs2022" -configuration "debug" -os "windows-2022" in local environment emit expected output for me.

Yet the doc about what needs to be done in order to add a new sample is fairly unclear to me. There is a Samples.md but it is not enough, many other things are not mentioned like how to properly make reference files, how to update launchSettings.json, etc.

Currently the new sample involves a copy action of Directory.Build.props file from codebase folder to project file location. I don't know if it is necessary to also include that copied one into reference folder for your CI to work in this specific case.

P.S. there is one thing needs to be beware of: in SamplesDef.json the target of ./RunProcess.ps1 -exeToRun is msbuild not nuget, because Microsoft deliberately prevents nuget.exe from working with such case, msbuild must be used.

[jspelletier]

you need to edit UpdateSamplesOutput.bat and run it. this will generate new references files.

[jspelletier]

the changes looks fine but the CI fails possibly due to the fact that you need to regenerate references(execute updatesamplesoutput.bat after edit)