Re: [RFH] zsh shell function portability issue

[Ralf Wildenhues]

* Paolo Bonzini wrote on Mon, Oct 13, 2008 at 11:59:22AM CEST:
> You will remember the shell function portability issue in zsh...

Yes; sigh.
 
> Do you think that these functions:

reindented to:

ac_func_c_try_compile()
{
  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:$LINENO: $ac_try_echo\""
      $as_echo "$ac_try_echo") >&5
      (eval "$ac_compile") 2>conftest.er1
      ac_status=$?
      grep -v '^ *+' conftest.er1 >conftest.err
      rm -f conftest.er1
      cat conftest.err >&5
      $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
      (exit $ac_status);
    } &&
    {
      test -z "$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.$ac_ext >&5
    ac_retval=1
  fi
  rm -f core conftest.err conftest.$ac_objext
  return $ac_retval
}

> 
> 
> and

ac_func_c_try_run()
{
  if
    { (ac_try="$ac_link"
      case "(($ac_try" in
        *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
        *) ac_try_echo=$ac_try;;
      esac
      eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
      $as_echo "$ac_try_echo") >&5
      (eval "$ac_link") 2>&5
      ac_status=$?
      $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
      (exit $ac_status);
    } &&
    { ac_try='./conftest$ac_exeext'
      {
        (case "(($ac_try" in
        *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
        *) ac_try_echo=$ac_try;;
        esac
        eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
        $as_echo "$ac_try_echo") >&5
        (eval "$ac_try") 2>&5
        ac_status=$?
        $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
        (exit $ac_status);
      };
    };
  then
    ac_retval=0
  else
    $as_echo "$as_me: program exited with status $ac_status" >&5
    $as_echo "$as_me: failed program was:" >&5
    sed 's/^/| /' conftest.$ac_ext >&5

    ac_retval=$ac_status
  fi

  rm -rf conftest.dSYM
  rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext
  conftest.$ac_objext conftest$ac_exeext
  return $ac_retval
}

> are portable?  (Yeah, the code is totally unreadable).

Pretty likely not:

$ zsh --version
zsh 4.2.3 (powerpc-apple-darwin8.0)
$ zsh
$ f () { ( exit 1); echo $?; }; f
0
$ f () { ( exit 1) && echo bad; }; f
bad
$ f () { { ( exit 1); } && echo bad; }; f
bad

> IMO the first should be okay because it only uses (exit ...) to drive an
> && construct.  In the second instead, I am worried about this:
> 
>   (eval "$ac_try") 2>&5
>   ac_status=$?
> 
> but do we need that eval at all?  Maybe it can be replaced with a {...}
> instead?

I'm pretty sure that application code relies on that eval, even if
lib/autoconf/*.m4 doesn't.  I don't think this can be changed without
much friction.

Cheers,
Ralf