1 # include_next.m4 serial 23 2 dnl Copyright (C) 2006-2012 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 dnl 28 dnl PRAGMA_COLUMNS can be used in files that override system header files, so 29 dnl as to avoid compilation errors on HP NonStop systems when the gnulib file 30 dnl is included by a system header file that does a "#pragma COLUMNS 80" (which 31 dnl has the effect of truncating the lines of that file and all files that it 32 dnl includes to 80 columns) and the gnulib file has lines longer than 80 33 dnl columns. 34 35 AC_DEFUN([gl_INCLUDE_NEXT], 36 [ 37 AC_LANG_PREPROC_REQUIRE() 38 AC_CACHE_CHECK([whether the preprocessor supports include_next], 39 [gl_cv_have_include_next], 40 [rm -rf conftestd1a conftestd1b conftestd2 41 mkdir conftestd1a conftestd1b conftestd2 42 dnl IBM C 9.0, 10.1 (original versions, prior to the 2009-01 updates) on 43 dnl AIX 6.1 support include_next when used as first preprocessor directive 44 dnl in a file, but not when preceded by another include directive. Check 45 dnl for this bug by including <stdio.h>. 46 dnl Additionally, with this same compiler, include_next is a no-op when 47 dnl used in a header file that was included by specifying its absolute 48 dnl file name. Despite these two bugs, include_next is used in the 49 dnl compiler's <math.h>. By virtue of the second bug, we need to use 50 dnl include_next as well in this case. 51 cat <<EOF > conftestd1a/conftest.h 52 #define DEFINED_IN_CONFTESTD1 53 #include_next <conftest.h> 54 #ifdef DEFINED_IN_CONFTESTD2 55 int foo; 56 #else 57 #error "include_next doesn't work" 58 #endif 59 EOF 60 cat <<EOF > conftestd1b/conftest.h 61 #define DEFINED_IN_CONFTESTD1 62 #include <stdio.h> 63 #include_next <conftest.h> 64 #ifdef DEFINED_IN_CONFTESTD2 65 int foo; 66 #else 67 #error "include_next doesn't work" 68 #endif 69 EOF 70 cat <<EOF > conftestd2/conftest.h 71 #ifndef DEFINED_IN_CONFTESTD1 72 #error "include_next test doesn't work" 73 #endif 74 #define DEFINED_IN_CONFTESTD2 75 EOF 76 gl_save_CPPFLAGS="$CPPFLAGS" 77 CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2" 78 dnl We intentionally avoid using AC_LANG_SOURCE here. 79 AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]], 80 [gl_cv_have_include_next=yes], 81 [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2" 82 AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]], 83 [gl_cv_have_include_next=buggy], 84 [gl_cv_have_include_next=no]) 85 ]) 86 CPPFLAGS="$gl_save_CPPFLAGS" 87 rm -rf conftestd1a conftestd1b conftestd2 88 ]) 89 PRAGMA_SYSTEM_HEADER= 90 if test $gl_cv_have_include_next = yes; then 91 INCLUDE_NEXT=include_next 92 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next 93 if test -n "$GCC"; then 94 PRAGMA_SYSTEM_HEADER='#pragma GCC system_header' 95 fi 96 else 97 if test $gl_cv_have_include_next = buggy; then 98 INCLUDE_NEXT=include 99 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next 100 else 101 INCLUDE_NEXT=include 102 INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include 103 fi 104 fi 105 AC_SUBST([INCLUDE_NEXT]) 106 AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE]) 107 AC_SUBST([PRAGMA_SYSTEM_HEADER]) 108 AC_CACHE_CHECK([whether system header files limit the line length], 109 [gl_cv_pragma_columns], 110 [dnl HP NonStop systems, which define __TANDEM, have this misfeature. 111 AC_EGREP_CPP([choke me], 112 [ 113 #ifdef __TANDEM 114 choke me 115 #endif 116 ], 117 [gl_cv_pragma_columns=yes], 118 [gl_cv_pragma_columns=no]) 119 ]) 120 if test $gl_cv_pragma_columns = yes; then 121 PRAGMA_COLUMNS="#pragma COLUMNS 10000" 122 else 123 PRAGMA_COLUMNS= 124 fi 125 AC_SUBST([PRAGMA_COLUMNS]) 126 ]) 127 128 # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...) 129 # ------------------------------------------ 130 # For each arg foo.h, if #include_next works, define NEXT_FOO_H to be 131 # '<foo.h>'; otherwise define it to be 132 # '"///usr/include/foo.h"', or whatever other absolute file name is suitable. 133 # Also, if #include_next works as first preprocessing directive in a file, 134 # define NEXT_AS_FIRST_DIRECTIVE_FOO_H to be '<foo.h>'; otherwise define it to 135 # be 136 # '"///usr/include/foo.h"', or whatever other absolute file name is suitable. 137 # That way, a header file with the following line: 138 # #@INCLUDE_NEXT@ @NEXT_FOO_H@ 139 # or 140 # #@INCLUDE_NEXT_AS_FIRST_DIRECTIVE@ @NEXT_AS_FIRST_DIRECTIVE_FOO_H@ 141 # behaves (after sed substitution) as if it contained 142 # #include_next <foo.h> 143 # even if the compiler does not support include_next. 144 # The three "///" are to pacify Sun C 5.8, which otherwise would say 145 # "warning: #include of /usr/include/... may be non-portable". 146 # Use '""', not '<>', so that the /// cannot be confused with a C99 comment. 147 # Note: This macro assumes that the header file is not empty after 148 # preprocessing, i.e. it does not only define preprocessor macros but also 149 # provides some type/enum definitions or function/variable declarations. 150 # 151 # This macro also checks whether each header exists, by invoking 152 # AC_CHECK_HEADERS_ONCE or AC_CHECK_HEADERS on each argument. 153 AC_DEFUN([gl_CHECK_NEXT_HEADERS], 154 [ 155 gl_NEXT_HEADERS_INTERNAL([$1], [check]) 156 ]) 157 158 # gl_NEXT_HEADERS(HEADER1 HEADER2 ...) 159 # ------------------------------------ 160 # Like gl_CHECK_NEXT_HEADERS, except do not check whether the headers exist. 161 # This is suitable for headers like <stddef.h> that are standardized by C89 162 # and therefore can be assumed to exist. 163 AC_DEFUN([gl_NEXT_HEADERS], 164 [ 165 gl_NEXT_HEADERS_INTERNAL([$1], [assume]) 166 ]) 167 168 # The guts of gl_CHECK_NEXT_HEADERS and gl_NEXT_HEADERS. 169 AC_DEFUN([gl_NEXT_HEADERS_INTERNAL], 170 [ 171 AC_REQUIRE([gl_INCLUDE_NEXT]) 172 AC_REQUIRE([AC_CANONICAL_HOST]) 173 174 m4_if([$2], [check], 175 [AC_CHECK_HEADERS_ONCE([$1]) 176 ]) 177 178 dnl FIXME: gl_next_header and gl_header_exists must be used unquoted 179 dnl until we can assume autoconf 2.64 or newer. 180 m4_foreach_w([gl_HEADER_NAME], [$1], 181 [AS_VAR_PUSHDEF([gl_next_header], 182 [gl_cv_next_]m4_defn([gl_HEADER_NAME])) 183 if test $gl_cv_have_include_next = yes; then 184 AS_VAR_SET(gl_next_header, ['<'gl_HEADER_NAME'>']) 185 else 186 AC_CACHE_CHECK( 187 [absolute name of <]m4_defn([gl_HEADER_NAME])[>], 188 m4_defn([gl_next_header]), 189 [m4_if([$2], [check], 190 [AS_VAR_PUSHDEF([gl_header_exists], 191 [ac_cv_header_]m4_defn([gl_HEADER_NAME])) 192 if test AS_VAR_GET(gl_header_exists) = yes; then 193 AS_VAR_POPDEF([gl_header_exists]) 194 ]) 195 AC_LANG_CONFTEST( 196 [AC_LANG_SOURCE( 197 [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]] 198 )]) 199 dnl AIX "xlc -E" and "cc -E" omit #line directives for header 200 dnl files that contain only a #include of other header files and 201 dnl no non-comment tokens of their own. This leads to a failure 202 dnl to detect the absolute name of <dirent.h>, <signal.h>, 203 dnl <poll.h> and others. The workaround is to force preservation 204 dnl of comments through option -C. This ensures all necessary 205 dnl #line directives are present. GCC supports option -C as well. 206 case "$host_os" in 207 aix*) gl_absname_cpp="$ac_cpp -C" ;; 208 *) gl_absname_cpp="$ac_cpp" ;; 209 esac 210 changequote(,) 211 case "$host_os" in 212 mingw*) 213 dnl For the sake of native Windows compilers (excluding gcc), 214 dnl treat backslash as a directory separator, like /. 215 dnl Actually, these compilers use a double-backslash as 216 dnl directory separator, inside the 217 dnl # line "filename" 218 dnl directives. 219 gl_dirsep_regex='[/\\]' 220 ;; 221 *) 222 gl_dirsep_regex='\/' 223 ;; 224 esac 225 dnl A sed expression that turns a string into a basic regular 226 dnl expression, for use within "/.../". 227 gl_make_literal_regex_sed='s,[]$^\\.*/[],\\&,g' 228 changequote([,]) 229 gl_header_literal_regex=`echo ']m4_defn([gl_HEADER_NAME])[' \ 230 | sed -e "$gl_make_literal_regex_sed"` 231 gl_absolute_header_sed="/${gl_dirsep_regex}${gl_header_literal_regex}/"'{ 232 s/.*"\(.*'"${gl_dirsep_regex}${gl_header_literal_regex}"'\)".*/\1/ 233 changequote(,)dnl 234 s|^/[^/]|//&| 235 changequote([,])dnl 236 p 237 q 238 }' 239 dnl eval is necessary to expand gl_absname_cpp. 240 dnl Ultrix and Pyramid sh refuse to redirect output of eval, 241 dnl so use subshell. 242 AS_VAR_SET(gl_next_header, 243 ['"'`(eval "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD | 244 sed -n "$gl_absolute_header_sed"`'"']) 245 m4_if([$2], [check], 246 [else 247 AS_VAR_SET(gl_next_header, ['<'gl_HEADER_NAME'>']) 248 fi 249 ]) 250 ]) 251 fi 252 AC_SUBST( 253 AS_TR_CPP([NEXT_]m4_defn([gl_HEADER_NAME])), 254 [AS_VAR_GET(gl_next_header)]) 255 if test $gl_cv_have_include_next = yes || test $gl_cv_have_include_next = buggy; then 256 # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include_next' 257 gl_next_as_first_directive='<'gl_HEADER_NAME'>' 258 else 259 # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include' 260 gl_next_as_first_directive=AS_VAR_GET(gl_next_header) 261 fi 262 AC_SUBST( 263 AS_TR_CPP([NEXT_AS_FIRST_DIRECTIVE_]m4_defn([gl_HEADER_NAME])), 264 [$gl_next_as_first_directive]) 265 AS_VAR_POPDEF([gl_next_header])]) 266 ]) 267 268 # Autoconf 2.68 added warnings for our use of AC_COMPILE_IFELSE; 269 # this fallback is safe for all earlier autoconf versions. 270 m4_define_default([AC_LANG_DEFINES_PROVIDED]) 271
