1 # include_next.m4 serial 2
2 dnl Copyright (C) 2006, 2007 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 dnl From Paul Eggert and Derek Price.
9 AC_DEFUN([gl_INCLUDE_NEXT],
11 AC_LANG_PREPROC_REQUIRE()
12 AC_CACHE_CHECK([whether the preprocessor supports include_next],
13 [gl_cv_have_include_next],
14 [AC_PREPROC_IFELSE([#include_next <stddef.h>],
15 [gl_cv_have_include_next=yes],
16 [gl_cv_have_include_next=no])])
17 if test $gl_cv_have_include_next = yes; then
19 dnl FIXME: Remove HAVE_INCLUDE_NEXT and update everything that uses it
20 dnl to use @INCLUDE_NEXT@ instead.
21 AC_DEFINE([HAVE_INCLUDE_NEXT], 1,
22 [Define if your compiler supports the #include_next directive.])
24 INCLUDE_NEXT=include_next
28 AC_SUBST([INCLUDE_NEXT])
31 # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...)
32 # ------------------------------------------
33 # For each arg foo.h, if #include_next works, define NEXT_FOO_H to be
34 # '<foo.h>'; otherwise define it to be
35 # '"///usr/include/foo.h"', or whatever other absolute file name is suitable.
36 # That way, a header file with the following line:
37 # #@INCLUDE_NEXT@ @NEXT_FOO_H@
38 # behaves (after sed substitution) as if it contained
39 # #include_next <foo.h>
40 # even if the compiler does not support include_next.
41 # The three "///" are to pacify Sun C 5.8, which otherwise would say
42 # "warning: #include of /usr/include/... may be non-portable".
43 # Use `""', not `<>', so that the /// cannot be confused with a C99 comment.
44 AC_DEFUN([gl_CHECK_NEXT_HEADERS],
46 AC_REQUIRE([gl_INCLUDE_NEXT])
47 AC_CHECK_HEADERS_ONCE([$1])
49 AC_FOREACH([gl_HEADER_NAME], [$1],
50 [AS_VAR_PUSHDEF([gl_next_header],
51 [gl_cv_next_]m4_quote(m4_defn([gl_HEADER_NAME])))
52 AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
53 if test $gl_cv_have_include_next = no; then
55 [absolute name of <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
56 m4_quote(m4_defn([gl_next_header])),
57 [if test AS_VAR_GET([ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME]))) = yes; then
60 [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
62 dnl eval is necessary to expand ac_cpp.
63 dnl Ultrix and Pyramid sh refuse to redirect output of eval,
65 AS_VAR_SET([gl_next_header],
66 ['"'`(eval "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
67 sed -n '\#/]m4_quote(m4_defn([gl_HEADER_NAME]))[#{
68 s#.*"\(.*/]m4_quote(m4_defn([gl_HEADER_NAME]))[\)".*#\1#
76 AS_TR_CPP([NEXT_]m4_quote(m4_defn([gl_HEADER_NAME]))),
77 [AS_VAR_GET([gl_next_header])])
78 AS_VAR_POPDEF([gl_next_header])])