Should these restrictions be aligned with <input type=file accept>?

I don't see any reason why we couldn't align these restrictions, but it also matters less for <input type=file accept>. The security concerns are mostly about writing to files with dangerous extensions, so for security purposes I don't think we need to align them, but I don't see a reason why aligning would hurt either.

@kenchris and I looked at this today.

First of all, neither of us think we have ever seen a main.c++ file in the wild. Is that particular bit really needed, aside from this really weird case? (Unless this was a brown M&M, in which case well done!)

Otherwise, this looks like a sensible change.

I think that restriction to ASCII + "." makes a lot of sense - thought you can actually use emoji and control chars and the like in file extensions on Windows

Does any OS actually associate .c++ with an IDE? I have never in my life as a C++ developer seen ".c++" extension and maybe we can avoid whitelisting "+"

I don't think we should support "+" because then you could argue that we should also support "#" as some people and tools support for that C#

There is of course also ".c--":

Maybe we should just add "+", "-" and "#". @cynthia found another example of # used in the wild

And "$" and "!" :-)

Luckily I don't find anything else weird here:

https://en.wikipedia.org/wiki/List_of_filename_extensions_(A%E2%80%93E) (and other sections)

Almost forgot that ~ is also used in Linux for temporary files and also seen elsewhere:

So ["+", "-", "#", "$", "!", "~"] - I am fine with adding those, but just adding "+" and not the others seems strange

Hi @mkruisselbrink any feedback you can share based on Ken's comments above?

Sorry for the slow reply. The current list of characters is indeed fairly arbitrary. I think I originally did include most of what you're asking about (going of the wikipedia list), but got some push back that without clear use cases it was better to be as minimal as possible (because who knows what characters might have special meaning on particular file systems/operating systems). I agree that + is a bit of an odd one out in that regard. I believe I mostly went by what was in the freedesktop.org shared-mime-info database, which does include .c++, but none of the other characters (so yes, most linux installations will treat .c++ files as the same mime type as .cpp and .cc, and thus have the same applications associated with them).

I'd be fine with adding the rest, although so far nobody has asked for them yet.

Ok sounds good, we are good to close this then. Thanks for consulting the TAG.