1 # include_next.m4 serial 14 2 dnl Copyright (C) 2006-2009 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 IBM C 9.0, 10.1 (original versions, prior to the 2009-01 updates) on 36 dnl AIX 6.1 support include_next when used as first preprocessor directive 37 dnl in a file, but not when preceded by another include directive. Check 38 dnl for this bug by including <stdio.h>. 39 dnl Additionally, with this same compiler, include_next is a no-op when 40 dnl used in a header file that was included by specifying its absolute 41 dnl file name. Despite these two bugs, include_next is used in the 42 dnl compiler's <math.h>. By virtue of the second bug, we need to use 43 dnl include_next as well in this case. 44 cat <<EOF > conftestd1a/conftest.h 45 #define DEFINED_IN_CONFTESTD1 46 #include_next <conftest.h> 47 #ifdef DEFINED_IN_CONFTESTD2 48 int foo; 49 #else 50 #error "include_next doesn't work" 51 #endif 52 EOF 53 cat <<EOF > conftestd1b/conftest.h 54 #define DEFINED_IN_CONFTESTD1 55 #include <stdio.h> 56 #include_next <conftest.h> 57 #ifdef DEFINED_IN_CONFTESTD2 58 int foo; 59 #else 60 #error "include_next doesn't work" 61 #endif 62 EOF 63 cat <<EOF > conftestd2/conftest.h 64 #ifndef DEFINED_IN_CONFTESTD1 65 #error "include_next test doesn't work" 66 #endif 67 #define DEFINED_IN_CONFTESTD2 68 EOF 69 gl_save_CPPFLAGS="$CPPFLAGS" 70 CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2" 71 AC_COMPILE_IFELSE([#include <conftest.h>], 72 [gl_cv_have_include_next=yes], 73 [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2" 74 AC_COMPILE_IFELSE([#include <conftest.h>], 75 [gl_cv_have_include_next=buggy], 76 [gl_cv_have_include_next=no]) 77 ]) 78 CPPFLAGS="$gl_save_CPPFLAGS" 79 rm -rf conftestd1a conftestd1b conftestd2 80 ]) 81 PRAGMA_SYSTEM_HEADER= 82 if test $gl_cv_have_include_next = yes; then 83 INCLUDE_NEXT=include_next 84 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next 85 if test -n "$GCC"; then 86 PRAGMA_SYSTEM_HEADER='#pragma GCC system_header' 87 fi 88 else 89 if test $gl_cv_have_include_next = buggy; then 90 INCLUDE_NEXT=include 91 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next 92 else 93 INCLUDE_NEXT=include 94 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include 95 fi 96 fi 97 AC_SUBST([INCLUDE_NEXT]) 98 AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE]) 99 AC_SUBST([PRAGMA_SYSTEM_HEADER]) 100 ]) 101 102 # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...) 103 # ------------------------------------------ 104 # For each arg foo.h, if #include_next works, define NEXT_FOO_H to be 105 # '<foo.h>'; otherwise define it to be 106 # '"///usr/include/foo.h"', or whatever other absolute file name is suitable. 107 # Also, if #include_next works as first preprocessing directive in a file, 108 # define NEXT_AS_FIRST_DIRECTIVE_FOO_H to be '<foo.h>'; otherwise define it to 109 # be 110 # '"///usr/include/foo.h"', or whatever other absolute file name is suitable. 111 # That way, a header file with the following line: 112 # #@INCLUDE_NEXT@ @NEXT_FOO_H@ 113 # or 114 # #@INCLUDE_NEXT_AS_FIRST_DIRECTIVE@ @NEXT_AS_FIRST_DIRECTIVE_FOO_H@ 115 # behaves (after sed substitution) as if it contained 116 # #include_next <foo.h> 117 # even if the compiler does not support include_next. 118 # The three "///" are to pacify Sun C 5.8, which otherwise would say 119 # "warning: #include of /usr/include/... may be non-portable". 120 # Use `""', not `<>', so that the /// cannot be confused with a C99 comment. 121 # Note: This macro assumes that the header file is not empty after 122 # preprocessing, i.e. it does not only define preprocessor macros but also 123 # provides some type/enum definitions or function/variable declarations. 124 AC_DEFUN([gl_CHECK_NEXT_HEADERS], 125 [ 126 AC_REQUIRE([gl_INCLUDE_NEXT]) 127 AC_REQUIRE([AC_CANONICAL_HOST]) 128 AC_CHECK_HEADERS_ONCE([$1]) 129 130 m4_foreach_w([gl_HEADER_NAME], [$1], 131 [AS_VAR_PUSHDEF([gl_next_header], 132 [gl_cv_next_]m4_defn([gl_HEADER_NAME])) 133 if test $gl_cv_have_include_next = yes; then 134 AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>']) 135 else 136 AC_CACHE_CHECK( 137 [absolute name of <]m4_defn([gl_HEADER_NAME])[>], 138 m4_defn([gl_next_header]), 139 [AS_VAR_PUSHDEF([gl_header_exists], 140 [ac_cv_header_]m4_defn([gl_HEADER_NAME])) 141 if test AS_VAR_GET(gl_header_exists) = yes; then 142 AC_LANG_CONFTEST( 143 [AC_LANG_SOURCE( 144 [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]] 145 )]) 146 dnl AIX "xlc -E" and "cc -E" omit #line directives for header files 147 dnl that contain only a #include of other header files and no 148 dnl non-comment tokens of their own. This leads to a failure to 149 dnl detect the absolute name of <dirent.h>, <signal.h>, <poll.h> 150 dnl and others. The workaround is to force preservation of comments 151 dnl through option -C. This ensures all necessary #line directives 152 dnl are present. GCC supports option -C as well. 153 case "$host_os" in 154 aix*) gl_absname_cpp="$ac_cpp -C" ;; 155 *) gl_absname_cpp="$ac_cpp" ;; 156 esac 157 dnl eval is necessary to expand gl_absname_cpp. 158 dnl Ultrix and Pyramid sh refuse to redirect output of eval, 159 dnl so use subshell. 160 AS_VAR_SET([gl_next_header], 161 ['"'`(eval "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD | 162 sed -n '\#/]m4_defn([gl_HEADER_NAME])[#{ 163 s#.*"\(.*/]m4_defn([gl_HEADER_NAME])[\)".*#\1# 164 s#^/[^/]#//&# 165 p 166 q 167 }'`'"']) 168 else 169 AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>']) 170 fi 171 AS_VAR_POPDEF([gl_header_exists])]) 172 fi 173 AC_SUBST( 174 AS_TR_CPP([NEXT_]m4_defn([gl_HEADER_NAME])), 175 [AS_VAR_GET([gl_next_header])]) 176 if test $gl_cv_have_include_next = yes || test $gl_cv_have_include_next = buggy; then 177 # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include_next' 178 gl_next_as_first_directive='<'gl_HEADER_NAME'>' 179 else 180 # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include' 181 gl_next_as_first_directive=AS_VAR_GET([gl_next_header]) 182 fi 183 AC_SUBST( 184 AS_TR_CPP([NEXT_AS_FIRST_DIRECTIVE_]m4_defn([gl_HEADER_NAME])), 185 [$gl_next_as_first_directive]) 186 AS_VAR_POPDEF([gl_next_header])]) 187 ]) 188
