If this isn't fixed, it should at least be documented.

Let me get some tests written to reproduce this, then I'll try to take a look.

To keep you in the loop, what it appears is happening is that it's searching for a configuration named Release and not Release, which are completely legal as currently specified. While for configurations, this may not be what is desired, we use the same mechanism for things like file filters, and most file systems allow for leading or trailing spaces on the file name (though it's likely not best practice for your filesystem). I am currently leaning towards a document the behavior explicitly and no code changes here. There are too many edge cases for this type of sanitization, leaving open a pretty large surface area for bugs.

Thanks for the update.

I would say documentation is the bare minimum here. It's an easy enough problem to work around - once you know what the problem is.

Would it be valid/make sense to print an error message if a filter refers to something it can't find?

I definitely agree that a documentation update for an immediate resolution is needed, and a future internal work task for the team to investigate input sanitization and normalization.

As for error messages, I don't think this would be appropriate. It's perfectly legal for it to match nothing, and that could be the expected behavior depending on the build set up. Perhaps a verbose log at the most would be useful here.

Yeah, I guess it's quite feasible to have filterable values only available on some platforms, etc. I do that myself, thinking about it.

Is it true to say not Release is a valid configuration? I can see that not Release (with two spaces) could be, but surely you have control over the not, no? (What happens if someone names something with a prefix of not ? Do you generate not not as the inverse? Or is not a reserved word at least?)

and a future internal work task for the team to investigate input sanitization and normalization.

As it currently stands, yes not Release would be a valid configuration name.