1 files changed, 83 insertions, 20 deletions

diff --git a/gl/m4/include_next.m4 b/gl/m4/include_next.m4
index 7ce472bc..062753c5 100644
--- a/gl/m4/include_next.m4
+++ b/gl/m4/include_next.m4
@@ -1,19 +1,46 @@
-# include_next.m4 serial 4
-dnl Copyright (C) 2006, 2007 Free Software Foundation, Inc.
+# include_next.m4 serial 10
+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.
 
 dnl From Paul Eggert and Derek Price.
 
+dnl Sets INCLUDE_NEXT and PRAGMA_SYSTEM_HEADER.
+dnl
+dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to
+dnl 'include' otherwise.
+dnl
+dnl INCLUDE_NEXT_AS_FIRST_DIRECTIVE expands to 'include_next' if the compiler
+dnl supports it in the special case that it is the first include directive in
+dnl the given file, or to 'include' otherwise.
+dnl
+dnl PRAGMA_SYSTEM_HEADER can be used in files that contain #include_next,
+dnl so as to avoid GCC warnings when the gcc option -pedantic is used.
+dnl '#pragma GCC system_header' has the same effect as if the file was found
+dnl through the include search path specified with '-isystem' options (as
+dnl opposed to the search path specified with '-I' options). Namely, gcc
+dnl does not warn about some things, and on some systems (Solaris and Interix)
+dnl __STDC__ evaluates to 0 instead of to 1. The latter is an undesired side
+dnl effect; we are therefore careful to use 'defined __STDC__' or '1' instead
+dnl of plain '__STDC__'.
+
 AC_DEFUN([gl_INCLUDE_NEXT],
 [
   AC_LANG_PREPROC_REQUIRE()
   AC_CACHE_CHECK([whether the preprocessor supports include_next],
     [gl_cv_have_include_next],
-    [rm -rf conftestd1 conftestd2
-     mkdir conftestd1 conftestd2
-     cat <<EOF > conftestd1/conftest.h
+    [rm -rf conftestd1a conftestd1b conftestd2
+     mkdir conftestd1a conftestd1b conftestd2
+     dnl The include of <stdio.h> is because IBM C 9.0 on AIX 6.1 supports
+     dnl include_next when used as first preprocessor directive in a file,
+     dnl but not when preceded by another include directive. Additionally,
+     dnl with this same compiler, include_next is a no-op when used in a
+     dnl header file that was included by specifying its absolute file name.
+     dnl Despite these two bugs, include_next is used in the compiler's
+     dnl <math.h>. By virtue of the second bug, we need to use include_next
+     dnl as well in this case.
+     cat <<EOF > conftestd1a/conftest.h
 #define DEFINED_IN_CONFTESTD1
 #include_next <conftest.h>
 #ifdef DEFINED_IN_CONFTESTD2
@@ -22,32 +49,53 @@ int foo;
 #error "include_next doesn't work"
 #endif
 EOF
+     cat <<EOF > conftestd1b/conftest.h
+#define DEFINED_IN_CONFTESTD1
+#include <stdio.h>
+#include_next <conftest.h>
+#ifdef DEFINED_IN_CONFTESTD2
+int foo;
+#else
+#error "include_next doesn't work"
+#endif
+EOF
      cat <<EOF > conftestd2/conftest.h
 #ifndef DEFINED_IN_CONFTESTD1
 #error "include_next test doesn't work"
 #endif
 #define DEFINED_IN_CONFTESTD2
 EOF
-     save_CPPFLAGS="$CPPFLAGS"
-     CPPFLAGS="$CPPFLAGS -Iconftestd1 -Iconftestd2"
+     gl_save_CPPFLAGS="$CPPFLAGS"
+     CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2"
      AC_COMPILE_IFELSE([#include <conftest.h>],
        [gl_cv_have_include_next=yes],
-       [gl_cv_have_include_next=no])
-     CPPFLAGS="$save_CPPFLAGS"
-     rm -rf conftestd1 conftestd2
+       [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2"
+        AC_COMPILE_IFELSE([#include <conftest.h>],
+          [gl_cv_have_include_next=buggy],
+          [gl_cv_have_include_next=no])
+       ])
+     CPPFLAGS="$gl_save_CPPFLAGS"
+     rm -rf conftestd1a conftestd1b conftestd2
     ])
+  PRAGMA_SYSTEM_HEADER=
   if test $gl_cv_have_include_next = yes; then
-
-    dnl FIXME: Remove HAVE_INCLUDE_NEXT and update everything that uses it
-    dnl to use @INCLUDE_NEXT@ instead.
-    AC_DEFINE([HAVE_INCLUDE_NEXT], 1,
-              [Define if your compiler supports the #include_next directive.])
-
     INCLUDE_NEXT=include_next
+    INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
+    if test -n "$GCC"; then
+      PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
+    fi
   else
-    INCLUDE_NEXT=include
+    if test $gl_cv_have_include_next = buggy; then
+      INCLUDE_NEXT=include
+      INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
+    else
+      INCLUDE_NEXT=include
+      INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include
+    fi
   fi
   AC_SUBST([INCLUDE_NEXT])
+  AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE])
+  AC_SUBST([PRAGMA_SYSTEM_HEADER])
 ])
 
 # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...)
@@ -63,12 +111,16 @@ EOF
 # 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_CHECK_NEXT_HEADERS],
 [
   AC_REQUIRE([gl_INCLUDE_NEXT])
+  AC_REQUIRE([AC_CANONICAL_HOST])
   AC_CHECK_HEADERS_ONCE([$1])
 
-  AC_FOREACH([gl_HEADER_NAME], [$1],
+  m4_foreach_w([gl_HEADER_NAME], [$1],
     [AS_VAR_PUSHDEF([gl_next_header],
                     [gl_cv_next_]m4_quote(m4_defn([gl_HEADER_NAME])))
      if test $gl_cv_have_include_next = yes; then
@@ -84,11 +136,22 @@ AC_DEFUN([gl_CHECK_NEXT_HEADERS],
               [AC_LANG_SOURCE(
                  [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
                )])
-            dnl eval is necessary to expand ac_cpp.
+            dnl AIX "xlc -E" and "cc -E" omit #line directives for header files
+            dnl that contain only a #include of other header files and no
+            dnl non-comment tokens of their own. This leads to a failure to
+            dnl detect the absolute name of <dirent.h>, <signal.h>, <poll.h>
+            dnl and others. The workaround is to force preservation of comments
+            dnl through option -C. This ensures all necessary #line directives
+            dnl are present. GCC supports option -C as well.
+            case "$host_os" in
+              aix*) gl_absname_cpp="$ac_cpp -C" ;;
+              *)    gl_absname_cpp="$ac_cpp" ;;
+            esac
+            dnl eval is necessary to expand gl_absname_cpp.
             dnl Ultrix and Pyramid sh refuse to redirect output of eval,
             dnl so use subshell.
             AS_VAR_SET([gl_next_header],
-              ['"'`(eval "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
+              ['"'`(eval "$gl_absname_cpp conftest.$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#^/[^/]#//&#