m4: ax_* update via autogen.sh

Signed-off-by: Michał Górny <mgorny@gentoo.org>

10 files changed, 105 insertions, 234 deletions

diff --git a/m4/ax_append_compile_flags.m4 b/m4/ax_append_compile_flags.m4
index 5b6f1af..9c85635 100644
--- a/m4/ax_append_compile_flags.m4
+++ b/m4/ax_append_compile_flags.m4
@@ -30,33 +30,12 @@
 #
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 6
+#serial 7
 
 AC_DEFUN([AX_APPEND_COMPILE_FLAGS],
 [AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
diff --git a/m4/ax_append_flag.m4 b/m4/ax_append_flag.m4
index e8c5312..dd6d8b6 100644
--- a/m4/ax_append_flag.m4
+++ b/m4/ax_append_flag.m4
@@ -23,33 +23,12 @@
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 7
+#serial 8
 
 AC_DEFUN([AX_APPEND_FLAG],
 [dnl
diff --git a/m4/ax_append_link_flags.m4 b/m4/ax_append_link_flags.m4
index 6f7f174..99b9fa5 100644
--- a/m4/ax_append_link_flags.m4
+++ b/m4/ax_append_link_flags.m4
@@ -28,33 +28,12 @@
 #
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 6
+#serial 7
 
 AC_DEFUN([AX_APPEND_LINK_FLAGS],
 [AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG])
diff --git a/m4/ax_cflags_force_c89.m4 b/m4/ax_cflags_force_c89.m4
index 59b33c1..815fb68 100644
--- a/m4/ax_cflags_force_c89.m4
+++ b/m4/ax_cflags_force_c89.m4
@@ -29,41 +29,19 @@
 #
 #   Copyright (c) 2009 Guido U. Draheim <guidod@gmx.de>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 10
+#serial 12
 
 AC_DEFUN([AX_CFLAGS_FORCE_C89],[dnl
 AS_VAR_PUSHDEF([FLAGS],[CFLAGS])dnl
 AS_VAR_PUSHDEF([VAR],[ac_cv_cflags_force_c89])dnl
 AC_CACHE_CHECK([m4_ifval($1,$1,FLAGS) for C89 mode],
 VAR,[VAR="no, unknown"
- AC_LANG_SAVE
- AC_LANG_C
+ AC_LANG_PUSH([C])
  ac_save_[]FLAGS="$[]FLAGS"
 for ac_arg dnl
 in "-pedantic  % -ansi -pedantic"             dnl GCC
@@ -76,11 +54,12 @@ in "-pedantic  % -ansi -pedantic"             dnl GCC
    "-h conform % -h conform"                  dnl Cray C (Unicos)
    #
 do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
-   AC_TRY_COMPILE([],[return 0;],
-   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],
+   [[return 0;]])],
+   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break],[])
 done
  FLAGS="$ac_save_[]FLAGS"
- AC_LANG_RESTORE
+ AC_LANG_POP([C])
 ])
 AS_VAR_POPDEF([FLAGS])dnl
 AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
diff --git a/m4/ax_cflags_no_writable_strings.m4 b/m4/ax_cflags_no_writable_strings.m4
index 48831fa..14478a6 100644
--- a/m4/ax_cflags_no_writable_strings.m4
+++ b/m4/ax_cflags_no_writable_strings.m4
@@ -30,33 +30,12 @@
 #
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 14
+#serial 16
 
 AC_DEFUN([AX_FLAGS_NO_WRITABLE_STRINGS],[dnl
 AS_VAR_PUSHDEF([FLAGS],[_AC_LANG_PREFIX[]FLAGS])dnl
@@ -79,18 +58,17 @@ in "-pedantic -Werror % -fno-writable-strings -Wwrite-strings" dnl   GCC
    "-fullwarn -use_readonly_const %% ok, its the default" dnl IRIX C
    #
 do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
-   AC_TRY_COMPILE([],[return 0;],
-   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [[return 0;]])],
+   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break],[])
 done
 case ".$VAR" in
    .|.no|.no,*) ;;
    *) # sanity check - testing strcpy() from string.h
       cp config.log config.tmp
-      AC_TRY_COMPILE([#include <string.h>],[
+      AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <string.h>]], [[
       char test[16];
-      if (strcpy (test, "test")) return 1;],
-      dnl the original did use test -n `$CC testprogram.c`
-      [if test `diff config.log config.tmp | grep -i warning | wc -l` != 0
+      if (strcpy (test, "test")) return 1;]])],[dnl the original did use test -n `$CC testprogram.c`
+      if test `diff config.log config.tmp | grep -i warning | wc -l` != 0
   then VAR="no, suppressed, string.h," ; fi],
       [VAR="no, suppressed, string.h"])
       rm config.tmp
diff --git a/m4/ax_cflags_strict_prototypes.m4 b/m4/ax_cflags_strict_prototypes.m4
index 1bc5db4..1a910cf 100644
--- a/m4/ax_cflags_strict_prototypes.m4
+++ b/m4/ax_cflags_strict_prototypes.m4
@@ -32,33 +32,12 @@
 #
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 16
+#serial 18
 
 AC_DEFUN([AX_FLAGS_STRICT_PROTOTYPES],[dnl
 AS_VAR_PUSHDEF([FLAGS],[_AC_LANG_PREFIX[]FLAGS])dnl
@@ -75,18 +54,18 @@ in "-pedantic -Werror % -fstrict-prototypes -Wstrict-prototypes" dnl   GCC
    "-pedantic % -Wstrict-prototypes %% no, unsupported" dnl oops
    #
 do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
-   AC_TRY_COMPILE([],[return 0;],
-   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
+   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [[return 0;]])],
+   [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break], [])
 done
 case ".$VAR" in
    .|.no|.no,*) ;;
    *) # sanity check with signal() from sys/signal.h
     cp config.log config.tmp
-    AC_TRY_COMPILE([#include <signal.h>],[
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <signal.h>]], [[
     if (signal (SIGINT, SIG_IGN) == SIG_DFL) return 1;
-    if (signal (SIGINT, SIG_IGN) != SIG_DFL) return 2;],
-    dnl the original did use test -n `$CC testprogram.c`
-    [if test `diff config.log config.tmp | grep -i warning | wc -l` != 0
+    if (signal (SIGINT, SIG_IGN) != SIG_DFL) return 2;]])],
+    [dnl the original did use test -n `$CC testprogram.c`
+    if test `diff config.log config.tmp | grep -i warning | wc -l` != 0
 then if test `diff config.log config.tmp | grep -i warning | wc -l` != 1
 then VAR="no, suppressed, signal.h," ; fi ; fi],
     [VAR="no, suppressed, signal.h"])
diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
index dcabb92..bd753b3 100644
--- a/m4/ax_check_compile_flag.m4
+++ b/m4/ax_check_compile_flag.m4
@@ -29,33 +29,12 @@
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 5
+#serial 6
 
 AC_DEFUN([AX_CHECK_COMPILE_FLAG],
 [AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
diff --git a/m4/ax_check_link_flag.m4 b/m4/ax_check_link_flag.m4
index 819409a..03a30ce 100644
--- a/m4/ax_check_link_flag.m4
+++ b/m4/ax_check_link_flag.m4
@@ -29,33 +29,12 @@
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   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.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <https://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
 
-#serial 5
+#serial 6
 
 AC_DEFUN([AX_CHECK_LINK_FLAG],
 [AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
diff --git a/m4/ax_compiler_flags_cflags.m4 b/m4/ax_compiler_flags_cflags.m4
index aeb16e3..916f918 100644
--- a/m4/ax_compiler_flags_cflags.m4
+++ b/m4/ax_compiler_flags_cflags.m4
@@ -19,13 +19,14 @@
 # LICENSE
 #
 #   Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
+#   Copyright (c) 2017, 2018 Reini Urban <rurban@cpan.org>
 #
 #   Copying and distribution of this file, with or without modification, are
 #   permitted in any medium without royalty provided the copyright notice
 #   and this notice are preserved.  This file is offered as-is, without any
 #   warranty.
 
-#serial 14
+#serial 17
 
 AC_DEFUN([AX_COMPILER_FLAGS_CFLAGS],[
     AC_REQUIRE([AC_PROG_SED])
@@ -39,6 +40,13 @@ AC_DEFUN([AX_COMPILER_FLAGS_CFLAGS],[
 
     AC_LANG_PUSH([C])
 
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
+      [#ifndef __cplusplus
+       #error "no C++"
+       #endif]])],
+      [ax_compiler_cxx=yes;],
+      [ax_compiler_cxx=no;])
+
     # Always pass -Werror=unknown-warning-option to get Clang to fail on bad
     # flags, otherwise they are always appended to the warn_cflags variable, and
     # Clang warns on them for every compilation unit.
@@ -64,23 +72,31 @@ AC_DEFUN([AX_COMPILER_FLAGS_CFLAGS],[
     ],ax_warn_cflags_variable,[$ax_compiler_flags_test])
 
     AS_IF([test "$ax_enable_compile_warnings" != "no"],[
+        if test "$ax_compiler_cxx" = "no" ; then
+            # C-only flags. Warn in C++
+            AX_APPEND_COMPILE_FLAGS([ dnl
+                -Wnested-externs dnl
+                -Wmissing-prototypes dnl
+                -Wstrict-prototypes dnl
+                -Wdeclaration-after-statement dnl
+                -Wimplicit-function-declaration dnl
+                -Wold-style-definition dnl
+                -Wjump-misses-init dnl
+            ],ax_warn_cflags_variable,[$ax_compiler_flags_test])
+        fi
+
         # "yes" flags
         AX_APPEND_COMPILE_FLAGS([ dnl
             -Wall dnl
             -Wextra dnl
             -Wundef dnl
-            -Wnested-externs dnl
             -Wwrite-strings dnl
             -Wpointer-arith dnl
             -Wmissing-declarations dnl
-            -Wmissing-prototypes dnl
-            -Wstrict-prototypes dnl
             -Wredundant-decls dnl
             -Wno-unused-parameter dnl
             -Wno-missing-field-initializers dnl
-            -Wdeclaration-after-statement dnl
             -Wformat=2 dnl
-            -Wold-style-definition dnl
             -Wcast-align dnl
             -Wformat-nonliteral dnl
             -Wformat-security dnl
@@ -96,10 +112,15 @@ AC_DEFUN([AX_COMPILER_FLAGS_CFLAGS],[
             -Wmissing-include-dirs dnl
             -Wunused-but-set-variable dnl
             -Warray-bounds dnl
-            -Wimplicit-function-declaration dnl
             -Wreturn-type dnl
             -Wswitch-enum dnl
             -Wswitch-default dnl
+            -Wduplicated-cond dnl
+            -Wduplicated-branches dnl
+            -Wlogical-op dnl
+            -Wrestrict dnl
+            -Wnull-dereference dnl
+            -Wdouble-promotion dnl
             $4 dnl
             $5 dnl
             $6 dnl
diff --git a/m4/ax_compiler_flags_ldflags.m4 b/m4/ax_compiler_flags_ldflags.m4
index 842e329..976d119 100644
--- a/m4/ax_compiler_flags_ldflags.m4
+++ b/m4/ax_compiler_flags_ldflags.m4
@@ -19,13 +19,14 @@
 # LICENSE
 #
 #   Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
+#   Copyright (c) 2017, 2018 Reini Urban <rurban@cpan.org>
 #
 #   Copying and distribution of this file, with or without modification, are
 #   permitted in any medium without royalty provided the copyright notice
 #   and this notice are preserved.  This file is offered as-is, without any
 #   warranty.
 
-#serial 8
+#serial 9
 
 AC_DEFUN([AX_COMPILER_FLAGS_LDFLAGS],[
     AX_REQUIRE_DEFINED([AX_APPEND_LINK_FLAGS])
@@ -48,7 +49,25 @@ AC_DEFUN([AX_COMPILER_FLAGS_LDFLAGS],[
         ax_compiler_flags_test=""
     ])
 
-    # macOS linker does not have --as-needed
+    AX_CHECK_LINK_FLAG([-Wl,--as-needed], [
+        AX_APPEND_LINK_FLAGS([-Wl,--as-needed],
+          [AM_LDFLAGS],[$ax_compiler_flags_test])
+    ])
+    AX_CHECK_LINK_FLAG([-Wl,-z,relro], [
+        AX_APPEND_LINK_FLAGS([-Wl,-z,relro],
+          [AM_LDFLAGS],[$ax_compiler_flags_test])
+    ])
+    AX_CHECK_LINK_FLAG([-Wl,-z,now], [
+        AX_APPEND_LINK_FLAGS([-Wl,-z,now],
+          [AM_LDFLAGS],[$ax_compiler_flags_test])
+    ])
+    AX_CHECK_LINK_FLAG([-Wl,-z,noexecstack], [
+        AX_APPEND_LINK_FLAGS([-Wl,-z,noexecstack],
+          [AM_LDFLAGS],[$ax_compiler_flags_test])
+    ])
+    # textonly, retpolineplt not yet
+
+    # macOS and cygwin linker do not have --as-needed
     AX_CHECK_LINK_FLAG([-Wl,--no-as-needed], [
         ax_compiler_flags_as_needed_option="-Wl,--no-as-needed"
     ], [