Re: debbugs, and a FAQ, for Autotools

[Russell Shaw]

On 20/02/11 06:10, Ralf Wildenhues wrote:
> Hi Russell,
>
> * Russell Shaw wrote on Mon, Feb 14, 2011 at 12:00:14AM CET:
> > I'd ask more about how the internals of ./configure and autoconf works.
>
> Can you formulate more specific questions?
>
> > And questions on how to make bison get handled without being forced to
> > mimic standard yacc.
>
> I've added that question there now (without answer so far).
>
> Thanks,
> Ralf

Hi,
I'm not in autoconf debugging mode atm, so i'll have to ask more detailed
things some other time.

Looking through a ./configure script, i see lots of things being done
with file descriptors >&5 and >&6. What is going on here? eg:


## ------------------------ ##
## Autoconf initialization. ##
## ------------------------ ##

# ac_fn_c_try_compile LINENO
# --------------------------
# Try to compile conftest.$ac_ext, and return whether this succeeded.
ac_fn_c_try_compile ()
{
  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
  rm -f conftest.$ac_objext
  if { { ac_try="$ac_compile"
case "(($ac_try" in
  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
  *) ac_try_echo=$ac_try;;
esac
eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
$as_echo "$ac_try_echo"; } >&5
  (eval "$ac_compile") 2>conftest.err
  ac_status=$?
  if test -s conftest.err; then
    grep -v '^ *+' conftest.err >conftest.er1
    cat conftest.er1 >&5
    mv -f conftest.er1 conftest.err
  fi
  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
  test $ac_status = 0; } && {
         test -z "$ac_c_werror_flag" ||
         test ! -s conftest.err
       } && test -s conftest.$ac_objext; then :
  ac_retval=0
else
  $as_echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5

        ac_retval=1
fi
  eval $as_lineno_stack; test "x$as_lineno_stack" = x && { as_lineno=; unset 
as_lineno;}
  as_fn_set_status $ac_retval

} # ac_fn_c_try_compile