using should check case of file name

[eschnett]

I accidentally typed using hDF5, and Julia accepted this. This should not have worked; the proper module name is HDF5 (with all upper case letters).

I am using OS X with a case-insensitive file system. That is, while the case of the file name is ignored when looking for a file, the file name still has a particular case that can be checked.

I would have expected Julia to reject the command using hDF5 by noting that yes, there is a file that can be opened under the name hDF5.jl, but this file's name is actually HDF5.jl, so it doesn't match.

[StefanKarpinski]

Yes, this would be a very good thing to change. When searching for filenames with using, we should additionally check that that the canonical name of the found file matches the expected case of it and not consider it to be a match if it doesn't, and thus continue to search. We may want to do the same for include, although that's less clear since that's more of a "load this file and eval it".

[ScottPJones]

This would be very good, I think it should also be done for include, to help prevent case typos from silently working on Windows and OS X case-insensitive file systems, and then code failing when moved to Unix/Linux or an OS X case-sensitive file system (like I normally use now).

[stevengj]

See also #9007 and Python PEP 235. (Python just implemented its own directory walking to solve this.)

[Sisyphuss]

I don't think that worth the work. Making it case sensitive is only a burden to the brain: 'TimeIt', "Timeit", or "timeit"? In addition, it will encourage people to use the same name with different cases to name different packages.

[stevengj]

@Sisyphuss, even if we wanted to allow case insensitivity (which would be inconsistent with the rest of Julia), the problem is that the behavior is inconsistent between platforms.

[malmaud]

Dup of #5789. Would be nice to get this fixed.