# include_next.m4 serial 14 dnl Copyright (C) 2006-2009 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 conftestd1a conftestd1b conftestd2 mkdir conftestd1a conftestd1b conftestd2 dnl IBM C 9.0, 10.1 (original versions, prior to the 2009-01 updates) on dnl AIX 6.1 support include_next when used as first preprocessor directive dnl in a file, but not when preceded by another include directive. Check dnl for this bug by including . dnl Additionally, with this same compiler, include_next is a no-op when dnl used in a header file that was included by specifying its absolute dnl file name. Despite these two bugs, include_next is used in the dnl compiler's . By virtue of the second bug, we need to use dnl include_next as well in this case. cat < conftestd1a/conftest.h #define DEFINED_IN_CONFTESTD1 #include_next #ifdef DEFINED_IN_CONFTESTD2 int foo; #else #error "include_next doesn't work" #endif EOF cat < conftestd1b/conftest.h #define DEFINED_IN_CONFTESTD1 #include #include_next #ifdef DEFINED_IN_CONFTESTD2 int foo; #else #error "include_next doesn't work" #endif EOF cat < conftestd2/conftest.h #ifndef DEFINED_IN_CONFTESTD1 #error "include_next test doesn't work" #endif #define DEFINED_IN_CONFTESTD2 EOF gl_save_CPPFLAGS="$CPPFLAGS" CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2" AC_COMPILE_IFELSE([#include ], [gl_cv_have_include_next=yes], [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2" AC_COMPILE_IFELSE([#include ], [gl_cv_have_include_next=buggy], [gl_cv_have_include_next=no]) ]) CPPFLAGS="$gl_save_CPPFLAGS" rm -rf conftestd1a conftestd1b conftestd2 ]) PRAGMA_SYSTEM_HEADER= if test $gl_cv_have_include_next = yes; then INCLUDE_NEXT=include_next INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next if test -n "$GCC"; then PRAGMA_SYSTEM_HEADER='#pragma GCC system_header' fi else 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 ...) # ------------------------------------------ # For each arg foo.h, if #include_next works, define NEXT_FOO_H to be # ''; otherwise define it to be # '"///usr/include/foo.h"', or whatever other absolute file name is suitable. # Also, if #include_next works as first preprocessing directive in a file, # define NEXT_AS_FIRST_DIRECTIVE_FOO_H to be ''; otherwise define it to # be # '"///usr/include/foo.h"', or whatever other absolute file name is suitable. # That way, a header file with the following line: # #@INCLUDE_NEXT@ @NEXT_FOO_H@ # or # #@INCLUDE_NEXT_AS_FIRST_DIRECTIVE@ @NEXT_AS_FIRST_DIRECTIVE_FOO_H@ # behaves (after sed substitution) as if it contained # #include_next # even if the compiler does not support include_next. # 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]) m4_foreach_w([gl_HEADER_NAME], [$1], [AS_VAR_PUSHDEF([gl_next_header], [gl_cv_next_]m4_defn([gl_HEADER_NAME])) if test $gl_cv_have_include_next = yes; then AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>']) else AC_CACHE_CHECK( [absolute name of <]m4_defn([gl_HEADER_NAME])[>], m4_defn([gl_next_header]), [AS_VAR_PUSHDEF([gl_header_exists], [ac_cv_header_]m4_defn([gl_HEADER_NAME])) if test AS_VAR_GET(gl_header_exists) = yes; then AC_LANG_CONFTEST( [AC_LANG_SOURCE( [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]] )]) dnl AIX "xlc -E" and "cc -E" omit #line directives for header files dnl that contain only a #include of other header files and no dnl non-comment tokens of their own. This leads to a failure to dnl detect the absolute name of , , dnl and others. The workaround is to force preservation of comments dnl through option -C. This ensures all necessary #line directives dnl are present. GCC supports option -C as well. case "$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 "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD | sed -n '\#/]m4_defn([gl_HEADER_NAME])[#{ s#.*"\(.*/]m4_defn([gl_HEADER_NAME])[\)".*#\1# s#^/[^/]#//&# p q }'`'"']) else AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>']) fi AS_VAR_POPDEF([gl_header_exists])]) fi AC_SUBST( AS_TR_CPP([NEXT_]m4_defn([gl_HEADER_NAME])), [AS_VAR_GET([gl_next_header])]) if test $gl_cv_have_include_next = yes || test $gl_cv_have_include_next = buggy; then # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include_next' gl_next_as_first_directive='<'gl_HEADER_NAME'>' else # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include' gl_next_as_first_directive=AS_VAR_GET([gl_next_header]) fi AC_SUBST( AS_TR_CPP([NEXT_AS_FIRST_DIRECTIVE_]m4_defn([gl_HEADER_NAME])), [$gl_next_as_first_directive]) AS_VAR_POPDEF([gl_next_header])]) ])