X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fonceonly.m4;h=4a3cd84d296a2d48854dfb4cc739a7c1ef4d23fc;hb=16b34ac99b135d6cd6c8c2cf1e277ee3b867d9ac;hp=2bf1590d59c99d962c65c1d4f5dbff21fda3abdc;hpb=b58955569f2b087e26d5182ff01827c65691c748;p=gnulib.git

diff --git a/m4/onceonly.m4 b/m4/onceonly.m4
index 2bf1590d5..4a3cd84d2 100644
--- a/m4/onceonly.m4
+++ b/m4/onceonly.m4
@@ -1,5 +1,6 @@
-# onceonly.m4 serial 5
-dnl Copyright (C) 2002-2003, 2005-2006, 2008 Free Software Foundation, Inc.
+# onceonly.m4 serial 6
+dnl Copyright (C) 2002-2003, 2005-2006, 2008-2010 Free Software Foundation,
+dnl Inc.
 dnl This file is free software, distributed under the terms of the GNU
 dnl General Public License.  As a special exception to the GNU General
 dnl Public License, this file may be distributed as part of a program
@@ -21,13 +22,16 @@ dnl inside an AC_DEFUNed function, the gl_CHECK_HEADERS macro call expands to
 dnl empty, and the check will be inserted before the body of the AC_DEFUNed
 dnl function.
 
-dnl This is like onceonly.m4, except that it uses diversions to named sections
-dnl DEFAULTS and INIT_PREPARE in order to check all requested headers at once,
-dnl thus reducing the size of 'configure'. Works with autoconf-2.57. The
-dnl size reduction is ca. 9%.
+dnl The original code implemented AC_CHECK_HEADERS_ONCE and AC_CHECK_FUNCS_ONCE
+dnl in terms of AC_DEFUN and AC_REQUIRE. This implementation uses diversions to
+dnl named sections DEFAULTS and INIT_PREPARE in order to check all requested
+dnl headers at once, thus reducing the size of 'configure'. It is known to work
+dnl with autoconf 2.57..2.62 at least . The size reduction is ca. 9%.
 
 dnl Autoconf version 2.59 plus gnulib is required; this file is not needed
-dnl with Autoconf 2.60 or greater.
+dnl with Autoconf 2.60 or greater. But note that autoconf's implementation of
+dnl AC_CHECK_DECLS_ONCE expects a comma-separated list of symbols as first
+dnl argument!
 AC_PREREQ([2.59])
 
 # AC_CHECK_HEADERS_ONCE(HEADER1 HEADER2 ...) is a once-only variant of