Re: config.cache considered harmful

[Paul Eggert]

I very much like the bug report quoted below, and I suggest that
it be put into the autoconf source code somewhere, either next to
the code that generates config.cache, or perhaps into a new section
of documentation that discusses autoconf portability issues.

It would also be helpful to put the Ultrix version number into the bug
report.

   Date: 25 Feb 2000 12:49:06 -0500
   From: Ian Lance Taylor <[EMAIL PROTECTED]>

   I can replicate this bug on Ultrix with this shell script:

   rm -f foo.cache
   ac_cv_path_M4=/usr/bin/m4
   (set) 2>&1 |
     sed -n "s/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/: \${\1='\2'}/p" \
     >> foo.cache
   /bin/sh -c '
     . foo.cache
     echo $ac_cv_path_M4
     (set) 2>&1 |
       sed -n "s/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/: \${\1='"'"'\2'"'"'}/p" \
       >> foo.cache
     echo $ac_cv_path_M4
     cat -v foo.cache'

   On Ultrix, the output is this:

   /usr/bin/m4
   /usr/bin/m4
   : ${ac_cv_path_M4='/usr/bin/m4'}
   : ${ac_cv_path_M4='M-/M-uM-sM-rM-/M-bM-iM-nM-/M-mM-4'}

   This bug does not happen if I change the use of /bin/sh in the script
   to /bin/sh5, and invoke the script with /bin/sh5.