-# include_next.m4 serial 1
-dnl Copyright (C) 2006 Free Software Foundation, Inc.
+# 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 with or without modifications, as long as this notice is preserved.
-dnl From Derek Price.
+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_CACHE_CHECK([whether the preprocessor supports include_next],
-[gl_cv_have_include_next],
-[AC_PREPROC_IFELSE([#include_next <stddef.h>],
- [gl_cv_have_include_next=yes],
- [gl_cv_have_include_next=no])])
-if test $gl_cv_have_include_next = yes; then
- AC_DEFINE([HAVE_INCLUDE_NEXT], 1,
- [Define if your compiler supports the #include_next directive.])
-fi
+[
+ AC_LANG_PREPROC_REQUIRE()
+ AC_CACHE_CHECK([whether the preprocessor supports include_next],
+ [gl_cv_have_include_next],
+ [rm -rf conftestd1 conftestd2
+ mkdir conftestd1 conftestd2
+ dnl The include of <stdio.h> is because IBM C 9.0 on AIX 6.1 supports
+ dnl include_next when used as first preprocessor directive in a file,
+ dnl but not when preceded by another include directive.
+ cat <<EOF > conftestd1/conftest.h
+#define DEFINED_IN_CONFTESTD1
+#include <stdio.h>
+#include_next <conftest.h>
+#ifdef DEFINED_IN_CONFTESTD2
+int foo;
+#else
+#error "include_next doesn't work"
+#endif
+EOF
+ cat <<EOF > conftestd2/conftest.h
+#ifndef DEFINED_IN_CONFTESTD1
+#error "include_next test doesn't work"
+#endif
+#define DEFINED_IN_CONFTESTD2
+EOF
+ save_CPPFLAGS="$CPPFLAGS"
+ CPPFLAGS="$CPPFLAGS -Iconftestd1 -Iconftestd2"
+ AC_COMPILE_IFELSE([#include <conftest.h>],
+ [gl_cv_have_include_next=yes],
+ [gl_cv_have_include_next=no])
+ CPPFLAGS="$save_CPPFLAGS"
+ rm -rf conftestd1 conftestd2
+ ])
+ PRAGMA_SYSTEM_HEADER=
+ if test $gl_cv_have_include_next = yes; then
+ INCLUDE_NEXT=include_next
+ if test -n "$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 ...)
+# ------------------------------------------
+# 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.
+# That way, a header file with the following line:
+# #@INCLUDE_NEXT@ @NEXT_FOO_H@
+# behaves (after sed substitution) as if it contained
+# #include_next <foo.h>
+# 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_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])))
+ if test $gl_cv_have_include_next = yes; then
+ AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
+ else
+ AC_CACHE_CHECK(
+ [absolute name of <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
+ m4_quote(m4_defn([gl_next_header])),
+ [AS_VAR_PUSHDEF([gl_header_exists],
+ [ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME])))
+ if test AS_VAR_GET(gl_header_exists) = yes; then
+ AC_LANG_CONFTEST(
+ [AC_LANG_SOURCE(
+ [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
+ )])
+ dnl eval is necessary to expand ac_cpp.
+ dnl Ultrix and Pyramid sh refuse to redirect output of eval,
+ dnl so use subshell.
+ AS_VAR_SET([gl_next_header],
+ ['"'`(eval "$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#
+ 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_quote(m4_defn([gl_HEADER_NAME]))),
+ [AS_VAR_GET([gl_next_header])])
+ AS_VAR_POPDEF([gl_next_header])])
])
projects / gnulib.git / blobdiff