[SCM] GNU Autoconf source repository branch, master, updated. v2.69-14-g45737f0

[Eric Blake]

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- Log -----------------------------------------------------------------
commit 45737f00b02eb455bc754e9b359fa192b9979786
Author: Eric Blake <address@hidden>
Date:   Wed Jul 18 14:53:24 2012 -0600

    doc: mention trap pitfalls
    
    Document why the previous patch was useful.
    
    * doc/autoconf.texi (Limitations of Builtins) <trap>: Mention the
    need to be defensive in trap handlers.

commit 2738235a0ce6ad225621474ef0d0c21c5095c177
Author: Andreas Schwab <address@hidden>
Date:   Wed Jul 18 22:23:14 2012 +0200

    general: Sanitize IFS in EXIT trap
    
    IFS may be modified temporarily when the configure script receives a
    signal.  Make sure the EXIT trap uses the standard value.
    
    * lib/autoconf/general.m4: Sanitize IFS in trap.
    * THANKS: Update.
    
    Copyright-paperwork-exempt: Yes

-----------------------------------------------------------------------

Summary of changes:
 THANKS                  |    2 +-
 doc/autoconf.texi       |   12 ++++++++++++
 lib/autoconf/general.m4 |    2 ++
 3 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/THANKS b/THANKS
index 8682c87..d90237d 100644
--- a/THANKS
+++ b/THANKS
@@ -33,7 +33,7 @@ Anders Kaseorg              address@hidden
 Andreas Buening             address@hidden
 Andreas Jaeger              address@hidden
 Andreas Schott              address@hidden
-Andreas Schwab              address@hidden
+Andreas Schwab              address@hidden
 Andreas Waechter            address@hidden
 Andrej Borsenkow            address@hidden
 Andrew Belov                ?
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 506d966..927921c 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -18346,6 +18346,18 @@ $ @kbd{bash-2.05b -c 'trap ":; /bin/true" 0; exit 2'; 
echo $?}
 2
 @end example
 
+Be aware that a trap can be called from any number of places in your
+script, and therefore the trap handler should not make assumptions about
+shell state.  For some examples, if your script temporarily modifies
address@hidden, then the trap should include an initialization back to its
+typical value of space-tab-newline (autoconf does this for generated
address@hidden files).  Likewise, if your script changes the current
+working directory at some point after the trap is installed, then your
+trap cannot assume which directory it is in, and should begin by
+changing directories to an absolute path if that is important to the
+cleanup efforts (autotest does this for generated @file{testsuite}
+files).
+
 @item @command{true}
 @c -----------------
 @prindex @command{true}
diff --git a/lib/autoconf/general.m4 b/lib/autoconf/general.m4
index adfae1d..d06fdf5 100644
--- a/lib/autoconf/general.m4
+++ b/lib/autoconf/general.m4
@@ -1266,6 +1266,8 @@ AS_UNSET(ac_configure_args1)
 # WARNING: Use '\'' to represent an apostrophe within the trap.
 # WARNING: Do not start the trap code with a newline, due to a FreeBSD 4.0 bug.
 trap 'exit_status=$?
+  # Sanitize IFS.
+  IFS=" ""     $as_nl"
   # Save into config.log some information that might help in debugging.
   {
     echo


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