ghc/cygwin filename resolution issue.

[Claus Reinke]

> Using ghc-5.04.2 under cygwin, and cygwin (v. 1.3.10-1), I'm having some
> horrible problems with inconistent treatment of filenames, especially
> when using (gnu, cygwin) make.  In a nutshell, make seems to be passing
> paths such as "/usr/local/hmake" (etc) to ghc, which is, as I understand
> it, interpretting these in a manner consistent with windows, but not with
> cygwin.  (i.e., it'd expect the above to be something like:
> /cygwin/usr/local/hmake, where the root of the cygwin installation is in
> c:\cygwin.  Experimenting with similar arguments to ghc by hand seems to
> confirm this.
> 
> Is there a work-around for this, or is using cygwin and ghc together just
> an out and out bad idea?

{another candidate for the ghc faq?-}

I'd say using absolute paths is a bad idea. cygwin/ghc is my main development
environment, and mostly problem-free. The pure-windows-ghc did cause the 
occasional headache with third-party tools, but the problem has so far not been 
on the cygwin or ghc side, but always in unwarranted assumptions in the 
construction of build processes.

In the examples I've seen of this conflict, the makefiles in question explicitly 
forced the use of absolute paths at some point or other. If you absolutely have 
to do this, 'cygpath' is your friend, ideally used at the places where those makefiles 
insist on doing ROOT=`pwd` or the like.. (if you can't catch the problem there at 
the root, you can still try to convert the paths before passing them to ghc proper,
but that might become messy).

The one occasion where this wasn't sufficient to resolve the issue was in the
case of nhc, compiled by ghc, but that was because ghc-compiled executables
also don't know about cygwin paths, and the nhc make system relies on feeding
the generated tools with absolute paths during the make process in a variety of
ways (AFAIR) - not impossible to resolve, but would be a lot of work..

[fiddling with the mount points may lead to other problems - I never saw
 a reason to try that]

Cheers,
Claus

$ cygpath --help
Usage: cygpath [-p|--path] (-u|--unix)|(-w|--windows [-s|--short-name]) filename

  -a|--absolute         output absolute path
  -c|--close handle     close handle (for use in captured process)
  -f|--file file        read file for input path information
  -i|--ignore           ignore missing argument
  -p|--path             filename argument is a path
  -s|--short-name       print Windows short form of filename
  -u|--unix             print Unix form of filename
  -v|--version          output version information and exit
  -w|--windows          print Windows form of filename
  -A|--allusers         use `All Users' instead of current user for -D, -P
  -D|--desktop          output `Desktop' directory and exit
  -P|--smprograms       output Start Menu `Programs' directory and exit
  -S|--sysdir           output system directory and exit
  -W|--windir           output `Windows' directory and exit