-# include_next.m4 serial 6
-dnl Copyright (C) 2006-2008 Free Software Foundation, Inc.
+# 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 conftestd1 conftestd2
- mkdir conftestd1 conftestd2
- cat <<EOF > conftestd1/conftest.h
+ [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 <stdio.h>.
+ 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 <math.h>. By virtue of the second bug, we need to use
+ dnl include_next as well in this case.
+ cat <<EOF > conftestd1a/conftest.h
#define DEFINED_IN_CONFTESTD1
#include_next <conftest.h>
#ifdef DEFINED_IN_CONFTESTD2
#else
#error "include_next doesn't work"
#endif
+EOF
+ cat <<EOF > conftestd1b/conftest.h
+#define DEFINED_IN_CONFTESTD1
+#include <stdio.h>
+#include_next <conftest.h>
+#ifdef DEFINED_IN_CONFTESTD2
+int foo;
+#else
+#error "include_next doesn't work"
+#endif
EOF
cat <<EOF > conftestd2/conftest.h
#ifndef DEFINED_IN_CONFTESTD1
#endif
#define DEFINED_IN_CONFTESTD2
EOF
- save_CPPFLAGS="$CPPFLAGS"
- CPPFLAGS="$CPPFLAGS -Iconftestd1 -Iconftestd2"
+ gl_save_CPPFLAGS="$CPPFLAGS"
+ CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2"
AC_COMPILE_IFELSE([#include <conftest.h>],
[gl_cv_have_include_next=yes],
- [gl_cv_have_include_next=no])
- CPPFLAGS="$save_CPPFLAGS"
- rm -rf conftestd1 conftestd2
+ [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2"
+ AC_COMPILE_IFELSE([#include <conftest.h>],
+ [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 $gl_cv_have_include_next = yes; then
-
- dnl FIXME: Remove HAVE_INCLUDE_NEXT and update everything that uses it
- dnl to use @INCLUDE_NEXT@ instead.
- AC_DEFINE([HAVE_INCLUDE_NEXT], 1,
- [Define if your compiler supports the #include_next directive.])
-
INCLUDE_NEXT=include_next
+ INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
+ if test -n "$GCC"; then
+ PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
+ fi
else
- INCLUDE_NEXT=include
+ 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
# '<foo.h>'; 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 '<foo.h>'; 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 <foo.h>
# even if the compiler does not support include_next.
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_quote(m4_defn([gl_HEADER_NAME])))
+ [gl_cv_next_]m4_defn([gl_HEADER_NAME]))
if test $gl_cv_have_include_next = yes; then
AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
else
AC_CACHE_CHECK(
- [absolute name of <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
- m4_quote(m4_defn([gl_next_header])),
+ [absolute name of <]m4_defn([gl_HEADER_NAME])[>],
+ m4_defn([gl_next_header]),
[AS_VAR_PUSHDEF([gl_header_exists],
- [ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME])))
+ [ac_cv_header_]m4_defn([gl_HEADER_NAME]))
if test AS_VAR_GET(gl_header_exists) = yes; then
AC_LANG_CONFTEST(
[AC_LANG_SOURCE(
[[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
)])
- dnl eval is necessary to expand ac_cpp.
+ dnl AIX "xlc -E" and "cc -E" omit #line directives for header files
+ dnl that contain only a #include of other header files and no
+ dnl non-comment tokens of their own. This leads to a failure to
+ dnl detect the absolute name of <dirent.h>, <signal.h>, <poll.h>
+ dnl and others. The workaround is to force preservation of comments
+ dnl through option -C. This ensures all necessary #line directives
+ dnl are present. GCC supports option -C as well.
+ case "$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 "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
- sed -n '\#/]m4_quote(m4_defn([gl_HEADER_NAME]))[#{
- s#.*"\(.*/]m4_quote(m4_defn([gl_HEADER_NAME]))[\)".*#\1#
+ ['"'`(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
AS_VAR_POPDEF([gl_header_exists])])
fi
AC_SUBST(
- AS_TR_CPP([NEXT_]m4_quote(m4_defn([gl_HEADER_NAME]))),
+ 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])])
])
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