AS_ECHO calls finding their way into calls

[BJ Terry]

Hello,

I'm relatively new to autoconf, and I'm having trouble getting the  
configure file to generate properly on another person's computer. It  
appears that when he uses the AC_ERLANG_CHECK_LIB macro, the configure  
file that's generated has an AC_ECHO still embedded in one of the  
strings to be called. To recreate the problem, we made a skeleton  
configure.ac containing only:

AC_INIT

AC_ERLANG_CHECK_LIB(erl_interface)


When my friend runs autoconf on the file, the relevant section (at  
least, I think this is where the problem lies) reads:

{ $as_echo "$as_me:$LINENO: checking for Erlang/OTP 'erl_interface'  
library subdirectory" >&5
$as_echo_n "checking for Erlang/OTP 'erl_interface' library  
subdirectory... " >&6; }
if test "${erlang_cv_lib_dir_erl_interface+set}" = set; then
   $as_echo_n "(cached) " >&6
else
   ac_ext=erl
ac_compile='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&5'
ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&5 ; echo "#!/bin/
sh" > conftest$ac_exeext ; AS_ECHO(["\"$ERL\" -run conftest start -run  
init stop -noshell"]) >> conftest$ac_exeext ; chmod +x conftest
$ac_exeext'
      if test "$cross_compiling" = yes; then
   { { $as_echo "$as_me:$LINENO: error: cannot run test program while  
cross compiling
See \`config.log' for more details." >&5
$as_echo "$as_me: error: cannot run test program while cross compiling
See \`config.log' for more details." >&2;}
    { (exit 1); exit 1; }; }
else

And when I run it, it reads:

{ echo "$as_me:$LINENO: checking for Erlang/OTP 'erl_interface'  
library subdirectory" >&5
echo $ECHO_N "checking for Erlang/OTP 'erl_interface' library  
subdirectory... $ECHO_C" >&6; }
if test "${erlang_cv_lib_dir_erl_interface+set}" = set; then
   echo $ECHO_N "(cached) $ECHO_C" >&6
else
   ac_ext=erl
ac_compile='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&5'
ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&5 ; echo "#!/bin/
sh" > conftest$ac_exeext ; echo "\"$ERL\" -run conftest start -run  
init stop -noshell" >> conftest$ac_exeext ; chmod +x conftest$ac_exeext'
      if test "$cross_compiling" = yes; then
   { { echo "$as_me:$LINENO: error: cannot run test program while  
cross compiling
See \`config.log' for more details." >&5
echo "$as_me: error: cannot run test program while cross compiling
See \`config.log' for more details." >&2;}
    { (exit 1); exit 1; }; }
else

Now, I did note that his has $as_echo wherever mine had just echo, and  
I don't know why that is, and don't know why google couldn't provide  
any useful links on the matter. The real problem appears to be that  
his "ac_link" variable has AS_ECHO in it instead of echo, which seems  
like it would cause problems to me. This is where he gets an error  
when running ./configure:

./configure: eval: line 1: syntax error near unexpected token `["\"$ERL
\" -run conftest start -run init stop -noshell"]'
./configure: eval: line 1: `$ERLC $ERLCFLAGS -b beam conftest.$ac_ext  
 >&5 ; echo "#!/bin/sh" > conftest$ac_exeext ; AS_ECHO(["\"$ERL\" -run  
conftest start -run init stop -noshell"]) >> conftest$ac_exeext ;  
chmod +x conftest$ac_exeext'


For the record, I am using autoconf 2.60 and M4 version 1.4.5, and he  
is using autoconf 2.62 and M4 version 1.4.11. My platform is Mac OS X  
10.5 running fink versions of these tools and he is using Mac OS X  
10.4 running the darwinports version, if that makes any difference.

Do any of you know what might be happening here, and what my next  
troubleshooting steps should be?

Thanks.


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[Eric Blake]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

According to BJ Terry on 9/15/2008 12:28 AM:
>
> AC_INIT
>
> AC_ERLANG_CHECK_LIB(erl_interface)

I'm not as familiar with Erlang, so it very well could be that you've
discovered a bug in autoconf.

>
> Now, I did note that his has $as_echo wherever mine had just echo, and I
> don't know why that is, and don't know why google couldn't provide any
> useful links on the matter.

Because the use of 'echo' is not always portable, so newer autoconf
guarantees a safe fallback (such as printf) in case it has detected that
your shell's echo does not fit autoconf's needs.

> The real problem appears to be that his
> "ac_link" variable has AS_ECHO in it instead of echo, which seems like
> it would cause problems to me.
>
> For the record, I am using autoconf 2.60 and M4 version 1.4.5, and he is
> using autoconf 2.62 and M4 version 1.4.11. My platform is Mac OS X 10.5
> running fink versions of these tools and he is using Mac OS X 10.4
> running the darwinports version, if that makes any difference.

It looks like you are reporting a regression that occurred sometime
between 2.60 and 2.62.  Could you please check whether 2.63 also has the
bug, so we can fix it?

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9@...
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[BJ Terry]

Eric,

It appears that you are right, and thanks for your help. When I  
upgraded to 2.63 on my machine it now exhibits the same problem.  
Digging around through all of the m4 files it looks like the offending  
function is

In 2.63 (erlang.m4):

# AC_LANG(Erlang)
# ---------------
m4_define([AC_LANG(Erlang)],
[ac_ext=erl
ac_compile='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext  
 >&AS_MESSAGE_LOG_FD'
ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext  
 >&AS_MESSAGE_LOG_FD ; echo "#!/bin/sh" > conftest$ac_exeext ;  
AS_ECHO(["\"$ERL\" -run conftest start -run init stop -noshell"]) >>  
conftest$ac_exeext ; chmod +x conftest$ac_exeext'
])

In 2.60 (erlang.m4):

# AC_LANG(Erlang)
# ---------------
m4_define([AC_LANG(Erlang)],
[ac_ext=erl
ac_compile='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext  
 >&AS_MESSAGE_LOG_FD'
ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext  
 >&AS_MESSAGE_LOG_FD ; echo "#!/bin/sh" > conftest$ac_exeext ; echo  
"\"$ERL\" -run conftest start -run init stop -noshell" >> conftest
$ac_exeext ; chmod +x conftest$ac_exeext'
])

I guess to fix this you would change it to read

# AC_LANG(Erlang)
# ---------------
m4_define([AC_LANG(Erlang)],
[ac_ext=erl
ac_compile='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext  
 >&AS_MESSAGE_LOG_FD'
ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext  
 >&AS_MESSAGE_LOG_FD ; echo "#!/bin/sh" > conftest$ac_exeext ;  
$as_echo $ERL -run conftest start -run init stop -noshell >> conftest
$ac_exeext ; chmod +x conftest$ac_exeext'
])

But why is there another echo statement in there? Do they each do  
something different?


On Sep 15, 2008, at 4:17 AM, Eric Blake wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> According to BJ Terry on 9/15/2008 12:28 AM:
>>
>> AC_INIT
>>
>> AC_ERLANG_CHECK_LIB(erl_interface)
>
> I'm not as familiar with Erlang, so it very well could be that you've
> discovered a bug in autoconf.
>
>>
>> Now, I did note that his has $as_echo wherever mine had just echo,  
>> and I
>> don't know why that is, and don't know why google couldn't provide  
>> any
>> useful links on the matter.
>
> Because the use of 'echo' is not always portable, so newer autoconf
> guarantees a safe fallback (such as printf) in case it has detected  
> that
> your shell's echo does not fit autoconf's needs.
>
>> The real problem appears to be that his
>> "ac_link" variable has AS_ECHO in it instead of echo, which seems  
>> like
>> it would cause problems to me.
>>
>> For the record, I am using autoconf 2.60 and M4 version 1.4.5, and  
>> he is
>> using autoconf 2.62 and M4 version 1.4.11. My platform is Mac OS X  
>> 10.5
>> running fink versions of these tools and he is using Mac OS X 10.4
>> running the darwinports version, if that makes any difference.
>
> It looks like you are reporting a regression that occurred sometime
> between 2.60 and 2.62.  Could you please check whether 2.63 also has  
> the
> bug, so we can fix it?
>
> - --
> Don't work too hard, make some time for fun as well!
>
> Eric Blake             ebb9@...
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.9 (Cygwin)
> Comment: Public key at home.comcast.net/~ericblake/eblake.gpg
> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org
>
> iEYEARECAAYFAkjORF4ACgkQ84KuGfSFAYCsfgCgsyKxi1ACHnSfN0iLYJhTZm7S
> gvUAnj96rSbrFWWeFe923PqukR2sFiie
> =oxP8
> -----END PGP SIGNATURE-----

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[Eric Blake]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

According to BJ Terry on 9/15/2008 11:36 PM:
> Eric,
>
> It appears that you are right, and thanks for your help. When I upgraded
> to 2.63 on my machine it now exhibits the same problem.

Thanks for the investigation.  And sadly, this means that both 2.62 and
2.63 are completely unusable with Erlang (maybe this warrants a 2.64
release soon?)

>
> I guess to fix this you would change it to read
>
> # AC_LANG(Erlang)
> # ---------------
> m4_define([AC_LANG(Erlang)],
> [ac_ext=erl
> ac_compile='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&AS_MESSAGE_LOG_FD'
> ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&AS_MESSAGE_LOG_FD ;
> echo "#!/bin/sh" > conftest$ac_exeext ; $as_echo $ERL -run conftest
> start -run init stop -noshell >> conftest$ac_exeext ; chmod +x
> conftest$ac_exeext'
> ])
>
> But why is there another echo statement in there? Do they each do
> something different?

Yes.  'echo "#!/bin/sh"' is safe (# cannot be confused with an option, and
the entire string contains no \).  'echo $ERL' is NOT safe ($ERL might
begin with a -, and be confused with an option, or might contain \, which
is not portable).  Hence the use of AS_ECHO, which guarantees the output
of an echo statement that will do the right thing.  The problem is that
AS_ECHO was overquoted (and the testsuite does not adequately test Erlang,
or this would have been caught more than a year ago).

Your proposed patch is insufficient (AS_ECHO does other things, such as
ensure that $as_echo is defined prior to this point in the script).  But
it is along the right lines; the AS_ECHO must be expanded (the bug was
that the # was underquoted, thus the AS_ECHO was intepreted as part of an
m4 comment; worse yet, this meant that the normal m4_pattern_forbid that
is supposed to catch unexpanded macros did not see it, because it does not
look in comments).  I'm committing this:

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9@...
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From c0215a0bb65ba266a1192b2cf32b64cfa4ef0275 Mon Sep 17 00:00:00 2001
From: Eric Blake <ebb9@...>
Date: Tue, 16 Sep 2008 06:37:51 -0600
Subject: [PATCH] Fix Erlang regression, introduced 2006-11-17.

* lib/autoconf/erlang.m4 (AC_LANG(Erlang)): Avoid overquoting.
* NEWS: Mention this fix.
* THANKS: Update.
Reported by BJ Terry.

Signed-off-by: Eric Blake <ebb9@...>
---
 ChangeLog              |    8 ++++++++
 NEWS                   |    5 +++++
 THANKS                 |    1 +
 lib/autoconf/erlang.m4 |    4 ++--
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index f01284d..448ae92 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
[phone]  Eric Blake  <ebb9@...>
+
+ Fix Erlang regression, introduced 2006-11-17.
+ * lib/autoconf/erlang.m4 (AC_LANG(Erlang)): Avoid overquoting.
+ * NEWS: Mention this fix.
+ * THANKS: Update.
+ Reported by BJ Terry.
+
 2008-09-13  Ralf Wildenhues  <Ralf.Wildenhues@...>
 
  * lib/autoconf/general.m4 (AC_CONFIG_AUX_DIRS): Improve a bit.
diff --git a/NEWS b/NEWS
index 4c997ad..0b027a1 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,10 @@
 GNU Autoconf NEWS - User visible changes.
 
+* Major changes in Autoconf 2.64 (????-??-??) [stable]
+  Released by Eric Blake, based on git versions 2.63.*.
+
+** AC_LANG_ERLANG works once again (regression introduced in 2.61a).
+
 * Major changes in Autoconf 2.63 (2008-09-09) [stable]
   Released by Eric Blake, based on git versions 2.62.*.
 
diff --git a/THANKS b/THANKS
index f1e2b04..f39e949 100644
diff --git a/lib/autoconf/erlang.m4 b/lib/autoconf/erlang.m4
index 7c2859c..9bed007 100644
--- a/lib/autoconf/erlang.m4
+++ b/lib/autoconf/erlang.m4
@@ -1,6 +1,6 @@
 # This file is part of Autoconf.                       -*- Autoconf -*-
 # Erlang/OTP language support.
-# Copyright (C) 2006 Free Software Foundation, Inc.
+# Copyright (C) 2006, 2008 Free Software Foundation, Inc.
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -124,7 +124,7 @@ fi
 m4_define([AC_LANG(Erlang)],
 [ac_ext=erl
 ac_compile='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&AS_MESSAGE_LOG_FD'
-ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&AS_MESSAGE_LOG_FD ; echo "#!/bin/sh" > conftest$ac_exeext ; AS_ECHO(["\"$ERL\" -run conftest start -run init stop -noshell"]) >> conftest$ac_exeext ; chmod +x conftest$ac_exeext'
+ac_link='$ERLC $ERLCFLAGS -b beam conftest.$ac_ext >&AS_MESSAGE_LOG_FD ; echo "[#]!/bin/sh" > conftest$ac_exeext ; AS_ECHO(["\"$ERL\" -run conftest start -run init stop -noshell"]) >> conftest$ac_exeext ; chmod +x conftest$ac_exeext'
 ])
 
 
--
1.6.0


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