2007-01-08 Bruno Haible <bruno@clisp.org>

[gnulib.git] / m4 / flexmember.m4

diff --git a/m4/flexmember.m4 b/m4/flexmember.m4
index 2a6ae47..eb5f2b1 100644 (file)
--- a/m4/flexmember.m4
+++ b/m4/flexmember.m4
@@ -1,21 +1,10 @@
+# serial 1
 # Check for flexible array member support.
 
 # Copyright (C) 2006 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
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
-
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-# 02110-1301, USA.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
 
 # Written by Paul Eggert.
 
@@ -41,7 +30,11 @@ AC_DEFUN([AC_C_FLEXIBLE_ARRAY_MEMBER],
       [Define to nothing if C supports flexible array members, and to
        1 if it does not.  That way, with a declaration like `struct s
        { int n; double d@<:@FLEXIBLE_ARRAY_MEMBER@:>@; };', the struct hack
-       can be used with pre-C99 compilers.])
+       can be used with pre-C99 compilers.
+       When computing the size of such an object, don't use 'sizeof (struct s)'
+       as it overestimates the size.  Use 'offsetof (struct s, d)' instead.
+       Don't use 'offsetof (struct s, d@<:@0@:>@)', as this doesn't work with
+       MSVC and with C++ compilers.])
   else
     AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], 1)
   fi