RE: Patch for Build under MSW + MSYS2

On Thu Feb 8 2018 Vincent Belaïche wrote:
> The CYGPATH_W variable is provided by autotools whathever the platform,
> but on all *nixy system that just does an echo.
> On MSWindows it converts the abolute path from the MSYS/Cygwin mount to
> the real MSWindows file system, for instance /usr/local/bin can be
> converted to C:\Programmes\msys64\usr\local\bin --- well actually you
> cannot guess without calling the cygpath command, it depends how
> Cygwin/Msys2 was installed.
> Concerning the second comment I can send another patch with the
> simplified as much as possible way:
> 
>  abs_target=`$(CYGPATH_W) $(abs_builddir)/$@ | sed 's/\\([\\]\\)/\\\\\\1/g'`; \
> 
> Please note that it cannot be simplified further : I still need the pipe
> to sed command because cygwin -w use the \ filename separator, so that
> needs to be elisp-string escaped.

Thanks, I see.  Can you please include comments in your patch
explaining briefly these two things (in the context of your patch)?

- Why is it necessary in a cygwin environment to call cygpath at
  this place?

- Why is cygpath not enough for generating lisp code?