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date Sun, 16 Aug 2009 17:16:49 +0000
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271:3b793ba7a6c6 272:d5392bb5da3c
1 # include_next.m4 serial 10
2 dnl Copyright (C) 2006-2008 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.
6
7 dnl From Paul Eggert and Derek Price.
8
9 dnl Sets INCLUDE_NEXT and PRAGMA_SYSTEM_HEADER.
10 dnl
11 dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to
12 dnl 'include' otherwise.
13 dnl
14 dnl INCLUDE_NEXT_AS_FIRST_DIRECTIVE expands to 'include_next' if the compiler
15 dnl supports it in the special case that it is the first include directive in
16 dnl the given file, or to 'include' otherwise.
17 dnl
18 dnl PRAGMA_SYSTEM_HEADER can be used in files that contain #include_next,
19 dnl so as to avoid GCC warnings when the gcc option -pedantic is used.
20 dnl '#pragma GCC system_header' has the same effect as if the file was found
21 dnl through the include search path specified with '-isystem' options (as
22 dnl opposed to the search path specified with '-I' options). Namely, gcc
23 dnl does not warn about some things, and on some systems (Solaris and Interix)
24 dnl __STDC__ evaluates to 0 instead of to 1. The latter is an undesired side
25 dnl effect; we are therefore careful to use 'defined __STDC__' or '1' instead
26 dnl of plain '__STDC__'.
27
28 AC_DEFUN([gl_INCLUDE_NEXT],
29 [
30 AC_LANG_PREPROC_REQUIRE()
31 AC_CACHE_CHECK([whether the preprocessor supports include_next],
32 [gl_cv_have_include_next],
33 [rm -rf conftestd1a conftestd1b conftestd2
34 mkdir conftestd1a conftestd1b conftestd2
35 dnl The include of <stdio.h> is because IBM C 9.0 on AIX 6.1 supports
36 dnl include_next when used as first preprocessor directive in a file,
37 dnl but not when preceded by another include directive. Additionally,
38 dnl with this same compiler, include_next is a no-op when used in a
39 dnl header file that was included by specifying its absolute file name.
40 dnl Despite these two bugs, include_next is used in the compiler's
41 dnl <math.h>. By virtue of the second bug, we need to use include_next
42 dnl as well in this case.
43 cat <<EOF > conftestd1a/conftest.h
44 #define DEFINED_IN_CONFTESTD1
45 #include_next <conftest.h>
46 #ifdef DEFINED_IN_CONFTESTD2
47 int foo;
48 #else
49 #error "include_next doesn't work"
50 #endif
51 EOF
52 cat <<EOF > conftestd1b/conftest.h
53 #define DEFINED_IN_CONFTESTD1
54 #include <stdio.h>
55 #include_next <conftest.h>
56 #ifdef DEFINED_IN_CONFTESTD2
57 int foo;
58 #else
59 #error "include_next doesn't work"
60 #endif
61 EOF
62 cat <<EOF > conftestd2/conftest.h
63 #ifndef DEFINED_IN_CONFTESTD1
64 #error "include_next test doesn't work"
65 #endif
66 #define DEFINED_IN_CONFTESTD2
67 EOF
68 gl_save_CPPFLAGS="$CPPFLAGS"
69 CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2"
70 AC_COMPILE_IFELSE([#include <conftest.h>],
71 [gl_cv_have_include_next=yes],
72 [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2"
73 AC_COMPILE_IFELSE([#include <conftest.h>],
74 [gl_cv_have_include_next=buggy],
75 [gl_cv_have_include_next=no])
76 ])
77 CPPFLAGS="$gl_save_CPPFLAGS"
78 rm -rf conftestd1a conftestd1b conftestd2
79 ])
80 PRAGMA_SYSTEM_HEADER=
81 if test $gl_cv_have_include_next = yes; then
82 INCLUDE_NEXT=include_next
83 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
84 if test -n "$GCC"; then
85 PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
86 fi
87 else
88 if test $gl_cv_have_include_next = buggy; then
89 INCLUDE_NEXT=include
90 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
91 else
92 INCLUDE_NEXT=include
93 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include
94 fi
95 fi
96 AC_SUBST([INCLUDE_NEXT])
97 AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE])
98 AC_SUBST([PRAGMA_SYSTEM_HEADER])
99 ])
100
101 # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...)
102 # ------------------------------------------
103 # For each arg foo.h, if #include_next works, define NEXT_FOO_H to be
104 # '<foo.h>'; otherwise define it to be
105 # '"///usr/include/foo.h"', or whatever other absolute file name is suitable.
106 # That way, a header file with the following line:
107 # #@INCLUDE_NEXT@ @NEXT_FOO_H@
108 # behaves (after sed substitution) as if it contained
109 # #include_next <foo.h>
110 # even if the compiler does not support include_next.
111 # The three "///" are to pacify Sun C 5.8, which otherwise would say
112 # "warning: #include of /usr/include/... may be non-portable".
113 # Use `""', not `<>', so that the /// cannot be confused with a C99 comment.
114 # Note: This macro assumes that the header file is not empty after
115 # preprocessing, i.e. it does not only define preprocessor macros but also
116 # provides some type/enum definitions or function/variable declarations.
117 AC_DEFUN([gl_CHECK_NEXT_HEADERS],
118 [
119 AC_REQUIRE([gl_INCLUDE_NEXT])
120 AC_REQUIRE([AC_CANONICAL_HOST])
121 AC_CHECK_HEADERS_ONCE([$1])
122
123 m4_foreach_w([gl_HEADER_NAME], [$1],
124 [AS_VAR_PUSHDEF([gl_next_header],
125 [gl_cv_next_]m4_quote(m4_defn([gl_HEADER_NAME])))
126 if test $gl_cv_have_include_next = yes; then
127 AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
128 else
129 AC_CACHE_CHECK(
130 [absolute name of <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
131 m4_quote(m4_defn([gl_next_header])),
132 [AS_VAR_PUSHDEF([gl_header_exists],
133 [ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME])))
134 if test AS_VAR_GET(gl_header_exists) = yes; then
135 AC_LANG_CONFTEST(
136 [AC_LANG_SOURCE(
137 [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
138 )])
139 dnl AIX "xlc -E" and "cc -E" omit #line directives for header files
140 dnl that contain only a #include of other header files and no
141 dnl non-comment tokens of their own. This leads to a failure to
142 dnl detect the absolute name of <dirent.h>, <signal.h>, <poll.h>
143 dnl and others. The workaround is to force preservation of comments
144 dnl through option -C. This ensures all necessary #line directives
145 dnl are present. GCC supports option -C as well.
146 case "$host_os" in
147 aix*) gl_absname_cpp="$ac_cpp -C" ;;
148 *) gl_absname_cpp="$ac_cpp" ;;
149 esac
150 dnl eval is necessary to expand gl_absname_cpp.
151 dnl Ultrix and Pyramid sh refuse to redirect output of eval,
152 dnl so use subshell.
153 AS_VAR_SET([gl_next_header],
154 ['"'`(eval "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
155 sed -n '\#/]m4_quote(m4_defn([gl_HEADER_NAME]))[#{
156 s#.*"\(.*/]m4_quote(m4_defn([gl_HEADER_NAME]))[\)".*#\1#
157 s#^/[^/]#//&#
158 p
159 q
160 }'`'"'])
161 else
162 AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
163 fi
164 AS_VAR_POPDEF([gl_header_exists])])
165 fi
166 AC_SUBST(
167 AS_TR_CPP([NEXT_]m4_quote(m4_defn([gl_HEADER_NAME]))),
168 [AS_VAR_GET([gl_next_header])])
169 AS_VAR_POPDEF([gl_next_header])])
170 ])