Re: Reverting from 1.7.0-45 [was Re: [1.7]: For the love of god, don't update!]

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Apr  6 10:08, Dave Korn wrote:
> Charles Wilson wrote:
> > Dave Korn wrote:
> > 
> >>   Forgot to say... can I see your "cygcheck -cd"?  I would have said "just m4
> >> and cygwin", but maybe it's related to something else.
> > 
> > Attached.  FWIW, I had no problems building other things, like
> > yesterday's p7zip packages or today's alternatives packages.
> 
>   Argh.  As one door opens, another slams viciously shut in my face.  For some
> reason autoconf has gone over to the dark side:
> 
> configure:1616: checking for i686-pc-cygwin-gcc
> configure:1642: result: cl
> configure:1926: checking for C compiler version
> configure:1929: cl --version </dev/null >&5
> Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8168 for 80x86
> Copyright (C) Microsoft Corp 1984-1998. All rights reserved.
> 
>   LOLWUT?  It turns out something has gone horribly wrong in the alternatives
> department now:
> 
> $ gcc
> bash: gcc: command not found
> 
> $ gcc.exe
> bash: gcc.exe: command not found
> 
> $ file /bin/gcc.exe
> /bin/gcc.exe: broken symbolic link to `/etc/alternatives/gcc'
> 
> $ ls /etc/alternatives/gcc -la
> lrwxrwxrwx 1 DKAdmin None 3 Apr  6 04:29 /etc/alternatives/gcc -> ??/

This happens if the symlink has been created with Cygwin 1.7.0-45
and you revert back to 1.7.0-44 or earlier.

I explained what I did to new symlinks in
http://cygwin.com/1.7/cygwin-ug-net/highlights.html#ov-hi-files,
9th paragraph:

  Starting with Cygwin 1.7, symbolic links are using UTF-16 to encode
  the filename of the target file, to better support
  internationalization. Symlinks created by older Cygwin releases can be
  read just fine. However, you could run into problems with them if
  you're now using another character set than the one you used when
  creating these symlinks (see the section called "Potential Problems".
  Please note that this new UTF-16 style of symlinks is not compatible
  with older Cygwin release, which can't read the target filename
  correctly.

I hope it's clear what the advantage is.  The disadvantage is also
clear, as you just found out.

Of course, what we could do is to store symlinks in UTF-8.  This would
have the advantage that these symlinks are compatible with old symlinks
as long as you only used ASCII characters.  The disadvantages are that
they are not backward compatible in a subtil way if they contain
non-ASCII characters, and their evaluation would be slower since you
would have one additional character set conversion per symlink read/write.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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