Doc tweak.

[gnulib.git] / m4 / absolute-header.m4

diff --git a/m4/absolute-header.m4 b/m4/absolute-header.m4
index c649df0..99f15ec 100644 (file)
--- a/m4/absolute-header.m4
+++ b/m4/absolute-header.m4
@@ -1,5 +1,5 @@
-# absolute-header.m4 serial 6
-dnl Copyright (C) 2006 Free Software Foundation, Inc.
+# absolute-header.m4 serial 9
+dnl Copyright (C) 2006-2008 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -16,9 +16,12 @@ dnl From Derek Price.
 # The three "///" are to pacify Sun C 5.8, which otherwise would say
 # "warning: #include of /usr/include/... may be non-portable".
 # Use `""', not `<>', so that the /// cannot be confused with a C99 comment.
+# Note: This macro assumes that the header file is not empty after
+# preprocessing, i.e. it does not only define preprocessor macros but also
+# provides some type/enum definitions or function/variable declarations.
 AC_DEFUN([gl_ABSOLUTE_HEADER],
 [AC_LANG_PREPROC_REQUIRE()dnl
-AC_FOREACH([gl_HEADER_NAME], [$1],
+m4_foreach_w([gl_HEADER_NAME], [$1],
   [AS_VAR_PUSHDEF([gl_absolute_header],
                   [gl_cv_absolute_]m4_quote(m4_defn([gl_HEADER_NAME])))dnl
   AC_CACHE_CHECK([absolute name of <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
@@ -32,7 +35,12 @@ dnl eval is necessary to expand ac_cpp.
 dnl Ultrix and Pyramid sh refuse to redirect output of eval, so use subshell.
       AS_VAR_SET(gl_absolute_header,
 [`(eval "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
-sed -n '\#/]m4_quote(m4_defn([gl_HEADER_NAME]))[#{s#.*"\(.*/]m4_quote(m4_defn([gl_HEADER_NAME]))[\)".*#\1#;s#^/[^/]#//&#;p;q;}'`])
+sed -n '\#/]m4_quote(m4_defn([gl_HEADER_NAME]))[#{
+       s#.*"\(.*/]m4_quote(m4_defn([gl_HEADER_NAME]))[\)".*#\1#
+       s#^/[^/]#//&#
+       p
+       q
+}'`])
     fi
     AS_VAR_POPDEF([ac_header_exists])dnl
     ])dnl