provided that does it conform to the standard behaviour on the given OS.

Perl's glob is platform independent. It behaves the same on all platforms

I personally believe that it is case sensitive under unices and case insensitive under Windows, for one thing. While I had naively and erroneously assumed this (along with other details!) was implemented with a selective loading of system specific modules, much like File::Spec does, or more simply by inserting the suitable sub out of a set into *CORE::GLOBAL::glob while it is much more simply and reasonably controlled by means of a single variable, I would definitely call that a different behavious across platforms.

It's done that way to allow glob('*.h *.c'), but I called it broken since patterns are usually already separated into multiple calls to glob

Actually, I see your point now, but I wouldn't go as far as calling it broken.

under Windows, it's not defined at all, being left to each individual application

They usually delegate to the FindFirstFile system call. Perl has File::DosGlob which resembles FindFirstFile

Thank you for sharing this, I didn't know.