ProjectGuid is obsolete and cannot guarantee a unique project instance

[3F]

MS drops support of the ProjectGuid in their projects files.
Means that some project files may not provide this at all. And as a result, it cannot guarantee a uniqueness on this basis anymore.

3F/DllExport#36 (comment)
3F/vsSolutionBuildEvent#40

MvsSln still can provide a unique ProjectGuid because it uses data from .sln file and its project files.

However, it still will not guarantee a normal work with project instances through MBE.

Alternative is

Full path to project file is a unique identifier for today. Therefore, we need to review some parts of our code that was based on ProjectGuid when working with projects (some filters, collections, and so on).

[DynConcepts]

Any citation for the removal by Microsoft.... In the general sense, absolute path does not identify a unique project (i.e. the same project could be cloned into multiple repositories).

[3F]

Any citation for the removal by Microsoft....

Ask Claire Novotny (Microsoft employee; .NET Foundation Executive Director, and PM on the .NET Team)
with whom I had a discussion in mentioned issue above.

In the general sense, absolute path does not identify a unique project (i.e. the same project could be cloned into multiple repositories).

What do you mean for "cloned into multiple repositories"? Please some example.

[DynConcepts]

Thanks. I will reach out to Claire (whom I already know) to see if the information has been published and available so I can easily refer people to authorized source...I know of much tooling that depends on these Guids...

As for Repos and Clones....

I could....
a) go to my C:\foo\A directory and do a "git clone https://github.com/3F/MvsSln" resulting in C:\foo\A\MvsSln...
b) go to my C:\foo\B directory and do a "git clone https://github.com/3F/MvsSln" resulting in C:\foo\B\MvsSln...

Now there are two clones of the repository (this is the simplest, but there are many more realistic yet complex examples -- perhaps a .csproj file that is published as part of two different repositories - perhaps one on GitHub and also on Azure Devops)..

In any case, "C:\foo" will now contain 2 of every unique .csproj.... but they "couples" will not have the same full path...

[3F]

I see. But in fact your case represents exactly a unique project instances that we really need as a feature.

In any case, "C:\foo" will now contain 2 of every unique .csproj.... but they "couples" will not have the same full path...

This case, however, is slightly different (as I see it) from initial ProjectGuid feature (I will keep naming an original property as a feature) and completely identical to DllExport problem in the past. And this is how it was resolved https://github.com/3F/DllExport/blob/e9b20af53dc84814f1bb94d4ef52c9605b94122e/Wizard/Project.cs#L83
(this is your case too)

ProjectGuid (again in my opinion) just adds unnecessary complexity leading to possible errors (copy-paste etc.).
But of course VS and MSBuild worlds are too different, here's example #25 (comment)