Re: AS_ECHO calls finding their way into calls

[Eric Blake]

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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             address@hidden
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>From c0215a0bb65ba266a1192b2cf32b64cfa4ef0275 Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
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 <address@hidden>
---
 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 @@
+2008-09-16  Eric Blake  <address@hidden>
+
+       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  <address@hidden>
 
        * 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