import-autoconf-fix-for-clang.patch

diff --git a/aclocal.m4 b/aclocal.m4
index a517e94..bfd34ec 100644
*** a/aclocal.m4
--- b/aclocal.m4
*************** m4_include([config/ax_prog_perl_modules.
*** 4,9 ****
--- 4,10 ----
  m4_include([config/ax_pthread.m4])
  m4_include([config/c-compiler.m4])
  m4_include([config/c-library.m4])
+ m4_include([config/check_decls.m4])
  m4_include([config/docbook.m4])
  m4_include([config/general.m4])
  m4_include([config/libtool.m4])
diff --git a/config/check_decls.m4 b/config/check_decls.m4
index ...0dda18b .
*** a/config/check_decls.m4
--- b/config/check_decls.m4
***************
*** 0 ****
--- 1,116 ----
+ # config/check_decls.m4
+ 
+ # This file redefines the standard Autoconf macro _AC_CHECK_DECL_BODY,
+ # and adds a supporting function _AC_UNDECLARED_WARNING, to make
+ # AC_CHECK_DECLS behave correctly when checking for built-in library
+ # functions with clang.
+ 
+ # This is based on commit 82ef7805faffa151e724aa76c245ec590d174580
+ # in the Autoconf git repository.  We can drop it if they ever get
+ # around to releasing a new version of Autoconf.  In the meantime,
+ # it's distributed under Autoconf's license:
+ 
+ # This file is part of Autoconf.  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 the
+ # Free Software Foundation, either version 3 of the License, or
+ # (at your option) any later version.
+ #
+ # This program is distributed in the hope that it will be useful,
+ # but WITHOUT ANY WARRANTY; without even the implied warranty of
+ # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ # GNU General Public License for more details.
+ #
+ # Under Section 7 of GPL version 3, you are granted additional
+ # permissions described in the Autoconf Configure Script Exception,
+ # version 3.0, as published by the Free Software Foundation.
+ #
+ # You should have received a copy of the GNU General Public License
+ # and a copy of the Autoconf Configure Script Exception along with
+ # this program; see the files COPYINGv3 and COPYING.EXCEPTION
+ # respectively.  If not, see <http://www.gnu.org/licenses/>.
+ 
+ # Written by David MacKenzie, with help from
+ # Franc,ois Pinard, Karl Berry, Richard Pixley, Ian Lance Taylor,
+ # Roland McGrath, Noah Friedman, david d zuhn, and many others.
+ 
+ 
+ # _AC_UNDECLARED_WARNING
+ # ----------------------
+ # Set ac_[]_AC_LANG_ABBREV[]_decl_warn_flag=yes if the compiler uses a warning,
+ # not a more-customary error, to report some undeclared identifiers.  Fail when
+ # an affected compiler warns also on valid input.  _AC_PROG_PREPROC_WORKS_IFELSE
+ # solves a related problem.
+ AC_DEFUN([_AC_UNDECLARED_WARNING],
+ [# The Clang compiler raises a warning for an undeclared identifier that matches
+ # a compiler builtin function.  All extant Clang versions are affected, as of
+ # Clang 3.6.0.  Test a builtin known to every version.  This problem affects the
+ # C and Objective C languages, but Clang does report an error under C++ and
+ # Objective C++.
+ #
+ # Passing -fno-builtin to the compiler would suppress this problem.  That
+ # strategy would have the advantage of being insensitive to stray warnings, but
+ # it would make tests less realistic.
+ AC_CACHE_CHECK([how $[]_AC_CC[] reports undeclared, standard C functions],
+ [ac_cv_[]_AC_LANG_ABBREV[]_decl_report],
+ [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [(void) strchr;])],
+   [AS_IF([test -s conftest.err], [dnl
+     # For AC_CHECK_DECL to react to warnings, the compiler must be silent on
+     # valid AC_CHECK_DECL input.  No library function is consistently available
+     # on freestanding implementations, so test against a dummy declaration.
+     # Include always-available headers on the off chance that they somehow
+     # elicit warnings.
+     AC_COMPILE_IFELSE([AC_LANG_PROGRAM([dnl
+ #include <float.h>
+ #include <limits.h>
+ #include <stdarg.h>
+ #include <stddef.h>
+ extern void ac_decl (int, char *);],
+ [@%:@ifdef __cplusplus
+   (void) ac_decl ((int) 0, (char *) 0);
+   (void) ac_decl;
+ @%:@else
+   (void) ac_decl;
+ @%:@endif
+ ])],
+       [AS_IF([test -s conftest.err],
+ 	[AC_MSG_FAILURE([cannot detect from compiler exit status or warnings])],
+ 	[ac_cv_[]_AC_LANG_ABBREV[]_decl_report=warning])],
+       [AC_MSG_FAILURE([cannot compile a simple declaration test])])],
+     [AC_MSG_FAILURE([compiler does not report undeclared identifiers])])],
+   [ac_cv_[]_AC_LANG_ABBREV[]_decl_report=error])])
+ 
+ case $ac_cv_[]_AC_LANG_ABBREV[]_decl_report in
+   warning) ac_[]_AC_LANG_ABBREV[]_decl_warn_flag=yes ;;
+   *) ac_[]_AC_LANG_ABBREV[]_decl_warn_flag= ;;
+ esac
+ ])# _AC_UNDECLARED_WARNING
+ 
+ # _AC_CHECK_DECL_BODY
+ # -------------------
+ # Shell function body for AC_CHECK_DECL.
+ m4_define([_AC_CHECK_DECL_BODY],
+ [  AS_LINENO_PUSH([$[]1])
+   # Initialize each $ac_[]_AC_LANG_ABBREV[]_decl_warn_flag once.
+   AC_DEFUN([_AC_UNDECLARED_WARNING_]_AC_LANG_ABBREV,
+ 	   [_AC_UNDECLARED_WARNING])dnl
+   AC_REQUIRE([_AC_UNDECLARED_WARNING_]_AC_LANG_ABBREV)dnl
+   [as_decl_name=`echo $][2|sed 's/ *(.*//'`]
+   [as_decl_use=`echo $][2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`]
+   AC_CACHE_CHECK([whether $as_decl_name is declared], [$[]3],
+   [ac_save_werror_flag=$ac_[]_AC_LANG_ABBREV[]_werror_flag
+   ac_[]_AC_LANG_ABBREV[]_werror_flag="$ac_[]_AC_LANG_ABBREV[]_decl_warn_flag$ac_[]_AC_LANG_ABBREV[]_werror_flag"
+   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$[]4],
+ [@%:@ifndef $[]as_decl_name
+ @%:@ifdef __cplusplus
+   (void) $[]as_decl_use;
+ @%:@else
+   (void) $[]as_decl_name;
+ @%:@endif
+ @%:@endif
+ ])],
+ 		   [AS_VAR_SET([$[]3], [yes])],
+ 		   [AS_VAR_SET([$[]3], [no])])])
+   ac_[]_AC_LANG_ABBREV[]_werror_flag=$ac_save_werror_flag
+   AS_LINENO_POP
+ ])# _AC_CHECK_DECL_BODY
diff --git a/configure b/configure
index 67b7700..cf4954f 100755
*** a/configure
--- b/configure
*************** fi
*** 1756,1768 ****
  ac_fn_c_check_decl ()
  {
    as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
!   as_decl_name=`echo $2|sed 's/ *(.*//'`
    as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
  $as_echo_n "checking whether $as_decl_name is declared... " >&6; }
  if eval \${$3+:} false; then :
    $as_echo_n "(cached) " >&6
  else
    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
  /* end confdefs.h.  */
  $4
--- 1756,1771 ----
  ac_fn_c_check_decl ()
  {
    as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
!   # Initialize each $ac_[]_AC_LANG_ABBREV[]_decl_warn_flag once.
!       as_decl_name=`echo $2|sed 's/ *(.*//'`
    as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
  $as_echo_n "checking whether $as_decl_name is declared... " >&6; }
  if eval \${$3+:} false; then :
    $as_echo_n "(cached) " >&6
  else
+   ac_save_werror_flag=$ac_c_werror_flag
+   ac_c_werror_flag="$ac_c_decl_warn_flag$ac_c_werror_flag"
    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
  /* end confdefs.h.  */
  $4
*************** fi
*** 1791,1796 ****
--- 1794,1800 ----
  eval ac_res=\$$3
  	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
  $as_echo "$ac_res" >&6; }
+   ac_c_werror_flag=$ac_save_werror_flag
    eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
  
  } # ac_fn_c_check_decl
*************** fi
*** 4990,4995 ****
--- 4994,5087 ----
    test -n "$AWK" && break
  done
  
+ # The Clang compiler raises a warning for an undeclared identifier that matches
+ # a compiler builtin function.  All extant Clang versions are affected, as of
+ # Clang 3.6.0.  Test a builtin known to every version.  This problem affects the
+ # C and Objective C languages, but Clang does report an error under C++ and
+ # Objective C++.
+ #
+ # Passing -fno-builtin to the compiler would suppress this problem.  That
+ # strategy would have the advantage of being insensitive to stray warnings, but
+ # it would make tests less realistic.
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking how $CC reports undeclared, standard C functions" >&5
+ $as_echo_n "checking how $CC reports undeclared, standard C functions... " >&6; }
+ if ${ac_cv_c_decl_report+:} false; then :
+   $as_echo_n "(cached) " >&6
+ else
+   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ /* end confdefs.h.  */
+ 
+ int
+ main ()
+ {
+ (void) strchr;
+   ;
+   return 0;
+ }
+ _ACEOF
+ if ac_fn_c_try_compile "$LINENO"; then :
+   if test -s conftest.err; then :
+       # For AC_CHECK_DECL to react to warnings, the compiler must be silent on
+     # valid AC_CHECK_DECL input.  No library function is consistently available
+     # on freestanding implementations, so test against a dummy declaration.
+     # Include always-available headers on the off chance that they somehow
+     # elicit warnings.
+     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ /* end confdefs.h.  */
+ #include <float.h>
+ #include <limits.h>
+ #include <stdarg.h>
+ #include <stddef.h>
+ extern void ac_decl (int, char *);
+ int
+ main ()
+ {
+ #ifdef __cplusplus
+   (void) ac_decl ((int) 0, (char *) 0);
+   (void) ac_decl;
+ #else
+   (void) ac_decl;
+ #endif
+ 
+   ;
+   return 0;
+ }
+ _ACEOF
+ if ac_fn_c_try_compile "$LINENO"; then :
+   if test -s conftest.err; then :
+   { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+ $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+ as_fn_error $? "cannot detect from compiler exit status or warnings
+ See \`config.log' for more details" "$LINENO" 5; }
+ else
+   ac_cv_c_decl_report=warning
+ fi
+ else
+   { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+ $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+ as_fn_error $? "cannot compile a simple declaration test
+ See \`config.log' for more details" "$LINENO" 5; }
+ fi
+ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ else
+   { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+ $as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+ as_fn_error $? "compiler does not report undeclared identifiers
+ See \`config.log' for more details" "$LINENO" 5; }
+ fi
+ else
+   ac_cv_c_decl_report=error
+ fi
+ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ fi
+ { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_c_decl_report" >&5
+ $as_echo "$ac_cv_c_decl_report" >&6; }
+ 
+ case $ac_cv_c_decl_report in
+   warning) ac_c_decl_warn_flag=yes ;;
+   *) ac_c_decl_warn_flag= ;;
+ esac
+ 
  if test "$with_llvm" = yes; then :