-# include_next.m4 serial 5
+# include_next.m4 serial 8
dnl Copyright (C) 2006-2008 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 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 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()
[gl_cv_have_include_next],
[rm -rf conftestd1 conftestd2
mkdir conftestd1 conftestd2
+ dnl The include of <stdio.h> is because IBM C 9.0 on AIX 6.1 supports
+ dnl include_next when used as first preprocessor directive in a file,
+ dnl but not when preceded by another include directive.
cat <<EOF > conftestd1/conftest.h
#define DEFINED_IN_CONFTESTD1
+#include <stdio.h>
#include_next <conftest.h>
#ifdef DEFINED_IN_CONFTESTD2
int foo;
CPPFLAGS="$save_CPPFLAGS"
rm -rf conftestd1 conftestd2
])
+ PRAGMA_SYSTEM_HEADER=
if test $gl_cv_have_include_next = yes; then
-
- dnl FIXME: Remove HAVE_INCLUDE_NEXT and update everything that uses it
- dnl to use @INCLUDE_NEXT@ instead.
- AC_DEFINE([HAVE_INCLUDE_NEXT], 1,
- [Define if your compiler supports the #include_next directive.])
-
INCLUDE_NEXT=include_next
+ if test -n "$GCC"; then
+ PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
+ fi
else
INCLUDE_NEXT=include
fi
AC_SUBST([INCLUDE_NEXT])
+ AC_SUBST([PRAGMA_SYSTEM_HEADER])
])
# gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...)
AC_REQUIRE([gl_INCLUDE_NEXT])
AC_CHECK_HEADERS_ONCE([$1])
- AC_FOREACH([gl_HEADER_NAME], [$1],
+ m4_foreach_w([gl_HEADER_NAME], [$1],
[AS_VAR_PUSHDEF([gl_next_header],
[gl_cv_next_]m4_quote(m4_defn([gl_HEADER_NAME])))
if test $gl_cv_have_include_next = yes; then