Re: [configure bus while building] flex beta version 2.5.15

[Bruce Lilly]

W. L. Estes wrote:
> On Wednesday, 21 August 2002,15:11 -0400, Bruce Lilly wrote:
>
>
> > are almost certainly configure issues on some platforms (I'll test
> > later today).
>
>
> Please let me know about any issues with configuration.
>
> Thanks,
>
> --Will


More configure/autoconf bugs:

1. configure frequently tests $?, which is usually unnecessary and
   always error-prone in a non-interactive shell.  It is far better
   to use the shell's if operator to test for command exit status, e.g.

if foo ; then
  : blah blah blah
else
  : yadda yadda yadda
fi

  Additionally, configure should
export PS1=""
  to ensure that there are no executable commands embedded in the
  prompt (which is a source of error when testing $?).

2. configure uses the following in a failed attempt to determine the
   default compiler output file name:

# Be careful to initialize this variable, since it used to be cached.
# Otherwise an old cache value of `no' led to `EXEEXT = no' in a Makefile.
ac_cv_exeext=
for ac_file in `ls a_out.exe a.exe conftest.exe 2>/dev/null;
                ls a.out conftest 2>/dev/null;
                ls a.* conftest.* 2>/dev/null`; do
  case $ac_file in
    *.$ac_ext | *.o | *.obj | *.xcoff | *.tds | *.d | *.pdb | *.xSYM ) ;;
    a.out ) # We found the default executable, but exeext='' is most
            # certainly right.
            break;;
    *.* ) ac_cv_exeext=`expr "$ac_file" : '[^.]*\(\..*\)'`
          # FIXME: I believe we export ac_cv_exeext for Libtool --akim.
          export ac_cv_exeext
          break;;
    * ) break;;
  esac
done

That's:
a: non-portable (in some cases, ls reports something like
   a_out.exe not found
   on stdout, which configure misinterprets as an indication that
   a_out.exe exists...)
and
b: inefficient

It should be something like:

# Be careful to initialize this variable, since it used to be cached.
# Otherwise an old cache value of `no' led to `EXEEXT = no' in a Makefile.
ac_cv_exeext=
for ac_file in a_out.exe a.exe conftest.exe a.out conftest a.* conftest.* ; do
  if test -x $ac_file ; then
    case $ac_file in
      *.$ac_ext | *.o | *.obj | *.xcoff | *.tds | *.d | *.pdb | *.xSYM ) ;;
      a.out ) # We found the default executable, but exeext='' is most
              # certainly right.
              break;;
      *.* ) ac_cv_exeext=`expr "$ac_file" : '[^.]*\(\..*\)'`
            # FIXME: I believe we export ac_cv_exeext for Libtool --akim.
            export ac_cv_exeext
            break;;
      * ) break;;
    esac
    break
  fi
done

There are similar tests throughout the configure script.

Best regards,
  Bruce Lilly