Re: [pygnulib] simplify cache configure.ac parsing

[Bruno Haible]

Hi Dmitry,

> BTW, the version from the pygnulib differs a bit already from the
> gnulib-tool shell script

The shell script contains this code (unchanged since 2009):

    guessed_auxdir="."
    guessed_libtool=false
    my_sed_traces='
      s,#.*$,,
      s,^dnl .*$,,
      s, dnl .*$,,
      /AC_CONFIG_AUX_DIR/ {
        s,^.*AC_CONFIG_AUX_DIR([[ ]*\([^]"$`\\)]*\).*$,guessed_auxdir="\1",p
      }
      /A[CM]_PROG_LIBTOOL/ {
        s,^.*$,guessed_libtool=true,p
      }'
    eval `sed -n -e "$my_sed_traces" < "$configure_ac"`

The first 3 lines of the sed script remove comments; I guess gnulib-tool.py
ought to do the same, because we really don't be fooled by invocations that
have been commented out.

>     "hello([AC_PREREQ([2.67])])"
>     "    AC_PREREQ([2.67])"
>     "helloAC_PREREQ([2.67])world"

You can reasonably assume that a configure.ac will not contain the first
or third of these lines, because AC_PREREQ (and likewise A[CM]_PROG_LIBTOOL)
are usually used at the top-level only. The second line can occur, though,
as there is no pressure on the programmers to use no indentation.

Bruno