Re: ensure a VPATH build

[Ralf Wildenhues]

Hi Keith,

* Keith Marshall wrote on Sat, Feb 18, 2006 at 11:26:30AM CET:
> On Friday 17 February 2006 1:12 pm, Ralf Wildenhues wrote:
> > >   pwd_curdir="`$1`"
> > >   pwd_srcdir="`cd $srcdir && $1`"
> >
> > The double quotes are not necessary here.
> 
> Not just unnecessary, but positively harmful.  Several shells will fail 
> to parse this correctly, *including* the MSYS version of bash.

Ouch.  I was referring to the fact that, on the right hand side of shell
assignments, no word splitting is done.  So
  foo=`echo bar baz`

will assign `bar baz' to `foo', not try to execute the command `baz'.

> See:
> https://sourceforge.net/mailarchive/message.php?msg_id=14306922
> https://sourceforge.net/mailarchive/message.php?msg_id=14354463

This is slightly different, and very bad: the MSYS sh wrongly expands
backquoted parts inside double-quoted parts.  But it is necessary to do
this sometimes, and I believe there are places in autotools that rely on
this.  Seems we need to work around them by using variable assignments
as intermediates.

Could you confirm that the bug also exists with assignments?

Have you filed a bug with bash or is this in a MSYS-specific issue only
so that the bug should be filed with MSYS?  Could you name other shells
which expose this bug?  We should probably add a warning to the Autoconf
shell portability section.

Cheers,
Ralf