No longer use CPP to check for the existing of headers: use CC to

check for compilability.

(_AC_CHECK_HEADER_MONGREL, AC_CHECK_HEADER, _AC_CHECK_HEADER_OLD): Remove.
(_AC_CHECK_HEADER_NEW): Rename as...
(AC_CHECK_HEADER): this.

diff --git a/lib/autoconf/headers.m4 b/lib/autoconf/headers.m4
index 3aff005d8359a16a44e895c31589e77094135200..366273043fd2bdadc6bd012d8dbf4d7dbdd556de 100644 (file)
--- a/lib/autoconf/headers.m4
+++ b/lib/autoconf/headers.m4
@@ -1,7 +1,7 @@
 # This file is part of Autoconf.                       -*- Autoconf -*-
 # Checking for headers.
-# Copyright 2000, 2001
-# Free Software Foundation, Inc.
+#
+# Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -67,83 +67,8 @@
 #                 [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
 #                 [INCLUDES])
 # ---------------------------------------------------------
-# We are slowly moving to checking headers with the compiler instead
-# of the preproc, so that we actually learn about the usability of a
-# header instead of its mere presence.  But since users are used to
-# the old semantics, they check for headers in random order and
-# without providing prerequisite headers.  This macro implements the
-# transition phase, and should be cleaned up latter to use compilation
-# only.
-#
-# If INCLUDES is empty, then check both via the compiler and preproc.
-# If the results are different, issue a warning, but keep the preproc
-# result.
-#
-# If INCLUDES is `-', keep only the old semantics.
-#
-# If INCLUDES is specified and different from `-', then use the new
-# semantics only.
-AC_DEFUN([AC_CHECK_HEADER],
-[m4_case([$4],
-         [],  [_AC_CHECK_HEADER_MONGREL($@)],
-         [-], [_AC_CHECK_HEADER_OLD($@)],
-              [_AC_CHECK_HEADER_NEW($@)])
-])# AC_CHECK_HEADER
-
-
-# _AC_CHECK_HEADER_MONGREL(HEADER-FILE,
-#                          [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
-#                          [INCLUDES])
-# --------------------------------------------------------------
-# Check using both the compiler and the preprocessor.  If they disagree,
-# warn, and the preproc wins.
-#
-# This is not based on _AC_CHECK_HEADER_NEW and _AC_CHECK_HEADER_OLD
-# because it obfuscate the code to try to factor everything, in particular
-# because of the cache variables, and the `checking...' messages.
-m4_define([_AC_CHECK_HEADER_MONGREL],
-[AS_VAR_PUSHDEF([ac_Header], [ac_cv_header_$1])dnl
-AS_VAR_SET_IF(ac_Header,
-              [AC_CACHE_CHECK([for $1], ac_Header, [])],
-              [# Is the header compilable?
-AC_MSG_CHECKING([$1 usability])
-AC_COMPILE_IFELSE([AC_LANG_SOURCE([AC_INCLUDES_DEFAULT([$4])
-@%:@include <$1>])],
-                  [ac_header_compiler=yes],
-                  [ac_header_compiler=no])
-AC_MSG_RESULT([$ac_header_compiler])
-
-# Is the header present?
-AC_MSG_CHECKING([$1 presence])
-AC_PREPROC_IFELSE([AC_LANG_SOURCE([@%:@include <$1>])],
-                  [ac_header_preproc=yes],
-                  [ac_header_preproc=no])
-AC_MSG_RESULT([$ac_header_preproc])
-
-# So?  What about this header?
-case $ac_header_compiler:$ac_header_preproc in
-  yes:no )
-    AC_MSG_WARN([$1: accepted by the compiler, rejected by the preprocessor!])
-    AC_MSG_WARN([$1: proceeding with the preprocessor's result]);;
-  no:yes )
-    AC_MSG_WARN([$1: present but cannot be compiled])
-    AC_MSG_WARN([$1: check for missing prerequisite headers?])
-    AC_MSG_WARN([$1: proceeding with the preprocessor's result]);;
-esac
-AC_CACHE_CHECK([for $1], ac_Header,
-               [AS_VAR_SET(ac_Header, $ac_header_preproc)])
-])dnl ! set ac_HEADER
-AS_IF([test AS_VAR_GET(ac_Header) = yes], [$2], [$3])[]dnl
-AS_VAR_POPDEF([ac_Header])dnl
-])# _AC_CHECK_HEADER_MONGREL
-
-
-# _AC_CHECK_HEADER_NEW(HEADER-FILE,
-#                      [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND],
-#                      [INCLUDES])
-# --------------------------------------------------------------
 # Check the compiler accepts HEADER-FILE.  The INCLUDES are defaulted.
-m4_define([_AC_CHECK_HEADER_NEW],
+AC_DEFUN([AC_CHECK_HEADER],
 [AS_VAR_PUSHDEF([ac_Header], [ac_cv_header_$1])dnl
 AC_CACHE_CHECK([for $1], ac_Header,
                [AC_COMPILE_IFELSE([AC_LANG_SOURCE([AC_INCLUDES_DEFAULT([$4])
@@ -152,22 +77,7 @@ AC_CACHE_CHECK([for $1], ac_Header,
                                   [AS_VAR_SET(ac_Header, no)])])
 AS_IF([test AS_VAR_GET(ac_Header) = yes], [$2], [$3])[]dnl
 AS_VAR_POPDEF([ac_Header])dnl
-])# _AC_CHECK_HEADER_NEW
-
-
-# _AC_CHECK_HEADER_OLD(HEADER-FILE,
-#                      [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
-# --------------------------------------------------------------
-# Check the preprocessor accepts HEADER-FILE.
-m4_define([_AC_CHECK_HEADER_OLD],
-[AS_VAR_PUSHDEF([ac_Header], [ac_cv_header_$1])dnl
-AC_CACHE_CHECK([for $1], ac_Header,
-               [AC_PREPROC_IFELSE([AC_LANG_SOURCE([@%:@include <$1>])],
-                                         [AS_VAR_SET(ac_Header, yes)],
-                                         [AS_VAR_SET(ac_Header, no)])])
-AS_IF([test AS_VAR_GET(ac_Header) = yes], [$2], [$3])[]dnl
-AS_VAR_POPDEF([ac_Header])dnl
-])# _AC_CHECK_HEADER_OLD
+])# AC_CHECK_HEADER
 
 
 # AH_CHECK_HEADERS(HEADER-FILE...)