Document that Autoconf relies on IFS.

* doc/autoconf.texi (Special Shell Variables) <IFS>: Add details
about use of IFS within configure script.
* THANKS: Update.
Reported by Arkadiusz Miskiewicz.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/ChangeLog b/ChangeLog
index 609d3afa9c17ec96c13b71e7f4ae166c13769f1b..6afb90ecdebe23d010243e274b8cb9f0dbe44288 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2010-02-26  Eric Blake  <eblake@redhat.com>
 
+       Document that Autoconf relies on IFS.
+       * doc/autoconf.texi (Special Shell Variables) <IFS>: Add details
+       about use of IFS within configure script.
+       * THANKS: Update.
+       Reported by Arkadiusz Miskiewicz.
+
        Recommend latest m4 release.
        * README: Bump recommendation to m4 1.4.14 (minimum remains
        1.4.6).

diff --git a/THANKS b/THANKS
index 8f90e90e8488c7fb92929774c754f5b44cdf7dd1..16dd8a317d84b525039bc4b1c3597364b56cda4c 100644 (file)
--- a/THANKS
+++ b/THANKS
@@ -38,6 +38,7 @@ Andrew Church               achurch@achurch.org
 Andrey Simonenko            simon@comsys.ntu-kpi.kiev.ua
 Andris Pavenis              andris.pavenis@iki.fi
 Anthony N. Frasso           afrasso@yahoo.com
+Arkadiusz Miskiewicz        arekm@maven.pl
 Art Haas                    ahaas@neosoft.com
 Arto C. Nirkko              ?
 Artur Frysiak               wiget@pld.org.pl

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 3709b0274312c8d081ace9b1e1de427867191c35..a669d06a18bb13e80bb31f794c286dcc1489a60d 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -15715,18 +15715,24 @@ Long ago, shell scripts inherited @env{IFS} from the environment,
 but this caused many problems so modern shells ignore any environment
 settings for @env{IFS}.
 
-Don't set the first character of @code{IFS} to backslash.  Indeed,
+Don't set the first character of @env{IFS} to backslash.  Indeed,
 Bourne shells use the first character (backslash) when joining the
 components in @samp{"$@@"} and some shells then reinterpret (!)@: the
 backslash escapes, so you can end up with backspace and other strange
 characters.
 
-The proper value for @code{IFS} (in regular code, not when performing
+The proper value for @env{IFS} (in regular code, not when performing
 splits) is @samp{@key{SPC}@key{TAB}@key{RET}}.  The first character is
 especially important, as it is used to join the arguments in @samp{$*};
 however, note that traditional shells, but also bash-2.04, fail to adhere
 to this and join with a space anyway.
 
+M4sh guarantees that @env{IFS} will have the default value at the
+beginning of a script, and many macros within autoconf rely on this
+setting.  It is okay to use blocks of shell code that temporarily change
+the value of @env{IFS} in order to split on another character, but
+remember to restore it before expanding further macros.
+
 @item LANG
 @itemx LC_ALL
 @itemx LC_COLLATE