RE: Bug Report: Regression in Cygwin 2.11.0-1

[David Allsopp <David.Allsopp@cl.cam.ac.uk>]

cyg Simple wrote:
> On 9/1/2018 5:52 PM, Andrey Repin wrote:
> > Greetings, David Allsopp!
> >
> >>> In terms of this OCAML build system problem:
> >>>
> >>> Please fix your build system.  Do not mix POSIX and Win32 paths, use
> >>> POSIX paths only.  Backslashes are *no* drop-in replacement for slashes.
> >
> >> The "problem" for us is more subtle than this. The program which is
> >> generating that path is not a Cygwin executable, so it is correctly
> >> combining a path it has been supplied (the ../stdlib which has been
> >> supplied via Cygwin's make) with a filename, so it uses a backslash.
> >> It's been on my TODO for years to enhance to understand that the
> >> program it's supplying the path back to is a Cygwin executable and so
> >> sort it out properly but, well, we're a small number of maintainers! That
> said, WSL is forcing us to address it properly...
> >
> > You CAN just send back forward slashes. Windows don't care.

That's not strictly true, as mkdir foo/bar will demonstrate in a command prompt (it is almost true when dealing with the Windows API). However, IMO, one looks like a Unix programmer who doesn't really understand Windows when your programs visibly use forward slashes everywhere. 

> > If any program would choke, it would be that program's problem after all.
> 
> Certainly not "that program's problem". The problem becomes mine and yours
> as we've not followed the design of the program.  While Windows at the
> moment doesn't care there is always the possibility that some fix could break
> that since the documentation states to use \ in paths and not /.  So while we
> "CAN just send back forward slashes" we need to be prepared for the outcome
> if something changes in an update to the OS and breaks the assumptions based
> on observed behavior rather than the documented behavior.

Just as an aside, the use of slashes is documented: see Kuhne's compulsory reading on the subject at https://blogs.msdn.microsoft.com/jeremykuhne/2016/04/21/path-normalization/ and also the notes in MSDN (https://docs.microsoft.com/en-gb/windows/desktop/FileIO/naming-a-file#maximum-path-length-limitation) which do mention that normalisation of / to \ in the API is not an accident.


David


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