git.m6w6.name Git - awesomized/libmemcached/blob - m4/ax_harden_compiler_flags.m4

   1 # vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
   2 # ===========================================================================
   3 #      https://github.com/BrianAker/ddm4/
   4 # ===========================================================================
   5 #
   6 # SYNOPSIS
   7 #
   8 #   AX_HARDEN_COMPILER_FLAGS() AX_HARDEN_LINKER_FLAGS()
   9 #
  10 # DESCRIPTION
  11 #
  12 #   Any compiler flag that "hardens" or tests code. C99 is assumed.
  13 #
  14 #   NOTE: Implementation based on AX_APPEND_FLAG.
  15 #
  16 # LICENSE
  17 #
  18 #  Copyright (C) 2012-2013 Brian Aker
  19 #  All rights reserved.
  20 #
  21 #  Redistribution and use in source and binary forms, with or without
  22 #  modification, are permitted provided that the following conditions are
  23 #  met:
  24 #
  25 #      * Redistributions of source code must retain the above copyright
  26 #  notice, this list of conditions and the following disclaimer.
  27 #
  28 #      * Redistributions in binary form must reproduce the above
  29 #  copyright notice, this list of conditions and the following disclaimer
  30 #  in the documentation and/or other materials provided with the
  31 #  distribution.
  32 #
  33 #      * The names of its contributors may not be used to endorse or
  34 #  promote products derived from this software without specific prior
  35 #  written permission.
  36 #
  37 #  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  38 #  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  39 #  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  40 #  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  41 #  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  42 #  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  43 #  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  44 #  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  45 #  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  46 #  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  47 #  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  48 #
  49 #  Notes:
  50 #  We do not test for c99 or c++11, that is out of scope.
  51
  52 # The Following flags are not checked for
  53 # -Wdeclaration-after-statement is counter to C99
  54 # _APPEND_COMPILE_FLAGS_ERROR([-pedantic])
  55
  56 #serial 10
  57
  58 AC_DEFUN([_WARNINGS_AS_ERRORS],
  59     [AC_CACHE_CHECK([if all warnings into errors],[ac_cv_warnings_as_errors],
  60       [AS_IF([test "x$ac_cv_vcs_checkout" = xyes],[ac_cv_warnings_as_errors=yes],
  61         [ac_cv_warnings_as_errors=no])
  62       ])
  63     ])
  64
  65 # Note: Should this be LIBS or LDFLAGS?
  66 AC_DEFUN([_APPEND_LINK_FLAGS_ERROR],
  67          [AC_REQUIRE([AX_APPEND_LINK_FLAGS])
  68          AX_APPEND_LINK_FLAGS([$1],[LDFLAGS],[-Werror])
  69          ])
  70
  71 AC_DEFUN([_APPEND_COMPILE_FLAGS_ERROR],
  72          [AC_REQUIRE([AX_APPEND_COMPILE_FLAGS])
  73          AX_APPEND_COMPILE_FLAGS([$1],,[-Werror])
  74          ])
  75
  76 # Everything above this does the heavy lifting, while what follows does the specifics.
  77
  78 AC_DEFUN([_HARDEN_LINKER_FLAGS],
  79         [AS_IF([test "$CC" != "clang"],
  80           [_APPEND_LINK_FLAGS_ERROR([-z relro -z now])
  81           AS_IF([test "x$ac_cv_warnings_as_errors" = xyes],[AX_APPEND_LINK_FLAGS([-Werror])])
  82           AS_IF([test "x$ac_cv_vcs_checkout" = xyes],[_APPEND_LINK_FLAGS_ERROR([-rdynamic])])
  83           ])
  84         ])
  85
  86 AC_DEFUN([_HARDEN_CC_COMPILER_FLAGS],
  87          [AC_LANG_PUSH([C])dnl
  88
  89          AS_IF([test "x$ax_enable_debug" = xyes],
  90            [CFLAGS=''
  91            _APPEND_COMPILE_FLAGS_ERROR([-H])
  92            _APPEND_COMPILE_FLAGS_ERROR([-ggdb])
  93            _APPEND_COMPILE_FLAGS_ERROR([-g])
  94            _APPEND_COMPILE_FLAGS_ERROR([-O0]),
  95            _APPEND_COMPILE_FLAGS_ERROR([-fno-omit-frame-pointer])
  96            ],[
  97            _APPEND_COMPILE_FLAGS_ERROR([-g])
  98            _APPEND_COMPILE_FLAGS_ERROR([-O2])
  99            ])
 100
 101          AS_IF([test "x$ac_cv_vcs_checkout" = xyes],
 102            [_APPEND_COMPILE_FLAGS_ERROR([-fstack-check])
 103            _APPEND_COMPILE_FLAGS_ERROR([-Wpragmas])
 104            _APPEND_COMPILE_FLAGS_ERROR([-Wunknown-pragmas])],
 105            [_APPEND_COMPILE_FLAGS_ERROR([-Wno-unknown-pragmas])
 106            _APPEND_COMPILE_FLAGS_ERROR([-Wno-pragmas])])
 107
 108          AS_IF([test "$CC" = "clang"],[_APPEND_COMPILE_FLAGS_ERROR([-Qunused-arguments])])
 109
 110          _APPEND_COMPILE_FLAGS_ERROR([-Wall])
 111          _APPEND_COMPILE_FLAGS_ERROR([-Wextra])
 112          _APPEND_COMPILE_FLAGS_ERROR([-Weverything])
 113          _APPEND_COMPILE_FLAGS_ERROR([-Wthis-test-should-fail])
 114 # Anything below this comment please keep sorted.
 115 # _APPEND_COMPILE_FLAGS_ERROR([-Wmissing-format-attribute])
 116           _APPEND_COMPILE_FLAGS_ERROR([-Wunsuffixed-float-constants])
 117           _APPEND_COMPILE_FLAGS_ERROR([-Wjump-misses-init])
 118           _APPEND_COMPILE_FLAGS_ERROR([-Wno-attributes])
 119           _APPEND_COMPILE_FLAGS_ERROR([-Waddress])
 120           _APPEND_COMPILE_FLAGS_ERROR([-Wvarargs])
 121           _APPEND_COMPILE_FLAGS_ERROR([-Warray-bounds])
 122           _APPEND_COMPILE_FLAGS_ERROR([-Wbad-function-cast])
 123 # Not in use -Wc++-compat
 124           _APPEND_COMPILE_FLAGS_ERROR([-Wchar-subscripts])
 125           _APPEND_COMPILE_FLAGS_ERROR([-Wcomment])
 126           _APPEND_COMPILE_FLAGS_ERROR([-Wfloat-equal])
 127           _APPEND_COMPILE_FLAGS_ERROR([-Wformat-security])
 128           _APPEND_COMPILE_FLAGS_ERROR([-Wformat=2])
 129           _APPEND_COMPILE_FLAGS_ERROR([-Wformat-y2k])
 130           _APPEND_COMPILE_FLAGS_ERROR([-Wlogical-op])
 131           _APPEND_COMPILE_FLAGS_ERROR([-Wmaybe-uninitialized])
 132           _APPEND_COMPILE_FLAGS_ERROR([-Wmissing-field-initializers])
 133           AS_IF([test "x$MINGW" = xyes],
 134                 [_APPEND_COMPILE_FLAGS_ERROR([-Wno-missing-noreturn])],
 135                 [_APPEND_COMPILE_FLAGS_ERROR([-Wmissing-noreturn])])
 136           _APPEND_COMPILE_FLAGS_ERROR([-Wmissing-prototypes])
 137           _APPEND_COMPILE_FLAGS_ERROR([-Wnested-externs])
 138           _APPEND_COMPILE_FLAGS_ERROR([-Wnormalized=id])
 139           _APPEND_COMPILE_FLAGS_ERROR([-Woverride-init])
 140           _APPEND_COMPILE_FLAGS_ERROR([-Wpointer-arith])
 141           _APPEND_COMPILE_FLAGS_ERROR([-Wpointer-sign])
 142           AS_IF([test "x$MINGW" = xyes],
 143                 [_APPEND_COMPILE_FLAGS_ERROR([-Wno-suggest-attribute=const])
 144                 _APPEND_COMPILE_FLAGS_ERROR([-Wno-suggest-attribute=noreturn])
 145                 _APPEND_COMPILE_FLAGS_ERROR([-Wno-suggest-attribute=pure])
 146                 _APPEND_COMPILE_FLAGS_ERROR([-Wno-redundant-decls])],
 147                 [_APPEND_COMPILE_FLAGS_ERROR([-Wredundant-decls])])
 148           _APPEND_COMPILE_FLAGS_ERROR([-Wshadow])
 149           _APPEND_COMPILE_FLAGS_ERROR([-Wshorten-64-to-32])
 150           _APPEND_COMPILE_FLAGS_ERROR([-Wsign-compare])
 151           _APPEND_COMPILE_FLAGS_ERROR([-Wstrict-overflow=1])
 152           _APPEND_COMPILE_FLAGS_ERROR([-Wstrict-prototypes])
 153           _APPEND_COMPILE_FLAGS_ERROR([-Wswitch-enum])
 154           _APPEND_COMPILE_FLAGS_ERROR([-Wtrampolines])
 155           _APPEND_COMPILE_FLAGS_ERROR([-Wundef])
 156           _APPEND_COMPILE_FLAGS_ERROR([-Wunsafe-loop-optimizations])
 157           _APPEND_COMPILE_FLAGS_ERROR([-funsafe-loop-optimizations])
 158           AS_IF([test "x$MINGW" != xyes],[
 159             AS_IF([test "x$ac_cv_vcs_checkout" = xyes],[
 160               AS_IF([test "x$enable_shared" = "xyes"],[
 161                 _APPEND_COMPILE_FLAGS_ERROR([-fno-omit-frame-pointer])
 162                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=address])
 163                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=integer])
 164                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=thread])
 165                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=memory])
 166                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=alignment])
 167                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=bool])
 168                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=bounds])
 169                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=enum])
 170                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=float-cast-overflow])
 171                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=float-divide-by-zero])
 172                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=integer-divide-by-zero])
 173                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=null])
 174                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=object-size])
 175                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=return])
 176                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=shift])
 177                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=signed-integer-overflow])
 178                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=unreachable])
 179                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=unsigned-integer-overflow])
 180                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=vla-bound])
 181                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=vptr])
 182               ])
 183             ])
 184           ])
 185           _APPEND_COMPILE_FLAGS_ERROR([-Wclobbered])
 186           _APPEND_COMPILE_FLAGS_ERROR([-Wunused])
 187           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-result])
 188           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-variable])
 189           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-parameter])
 190           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-local-typedefs])
 191           _APPEND_COMPILE_FLAGS_ERROR([-Wwrite-strings])
 192           _APPEND_COMPILE_FLAGS_ERROR([-floop-parallelize-all])
 193           _APPEND_COMPILE_FLAGS_ERROR([-fwrapv])
 194           _APPEND_COMPILE_FLAGS_ERROR([-fmudflapt])
 195           _APPEND_COMPILE_FLAGS_ERROR([-pipe])
 196           _APPEND_COMPILE_FLAGS_ERROR([-fPIE -pie])
 197           _APPEND_COMPILE_FLAGS_ERROR([-Wsizeof-pointer-memaccess])
 198           _APPEND_COMPILE_FLAGS_ERROR([-Wpacked])
 199           _APPEND_COMPILE_FLAGS_ERROR([-Wlong-long])
 200           _APPEND_COMPILE_FLAGS_ERROR([-Wunreachable-code])
 201
 202           AS_IF([test "x$ax_enable_debug" = xno],
 203             [AS_IF([test "x$ac_cv_vcs_checkout" = xyes],
 204               [AS_IF([test "x${target_os}" != "xmingw"],
 205                 [AS_IF([test "x$ac_c_gcc_recent" = xyes],
 206                   [_APPEND_COMPILE_FLAGS_ERROR([-D_FORTIFY_SOURCE=2])
 207                   #_APPEND_COMPILE_FLAGS_ERROR([-Wstack-protector])
 208                   #_APPEND_COMPILE_FLAGS_ERROR([-fstack-protector --param=ssp-buffer-size=4])
 209                   _APPEND_COMPILE_FLAGS_ERROR([-fstack-protector-all])
 210                   ])])])])
 211
 212          AS_IF([test "x$ac_cv_warnings_as_errors" = xyes],
 213              [AX_APPEND_FLAG([-Werror])])
 214
 215           AC_LANG_POP([C])
 216   ])
 217
 218 AC_DEFUN([_HARDEN_CXX_COMPILER_FLAGS],
 219          [AC_LANG_PUSH([C++])
 220          AC_REQUIRE([_APPEND_COMPILE_FLAGS_ERROR])
 221
 222          AS_IF([test "x$ax_enable_debug" = xyes],
 223            [CXXFLAGS=''
 224            _APPEND_COMPILE_FLAGS_ERROR([-H])
 225            _APPEND_COMPILE_FLAGS_ERROR([-ggdb])
 226            _APPEND_COMPILE_FLAGS_ERROR([-g])
 227            _APPEND_COMPILE_FLAGS_ERROR([-O0]),
 228            _APPEND_COMPILE_FLAGS_ERROR([-fno-omit-frame-pointer])
 229            ],[
 230            _APPEND_COMPILE_FLAGS_ERROR([-g])
 231            _APPEND_COMPILE_FLAGS_ERROR([-O2])
 232            ])
 233
 234          AS_IF([test "x$ac_cv_vcs_checkout" = xyes],
 235            [_APPEND_COMPILE_FLAGS_ERROR([-fstack-check])
 236            _APPEND_COMPILE_FLAGS_ERROR([-Wpragmas])
 237            _APPEND_COMPILE_FLAGS_ERROR([-Wunknown-pragmas])],
 238            [_APPEND_COMPILE_FLAGS_ERROR([-Wno-unknown-pragmas])
 239            _APPEND_COMPILE_FLAGS_ERROR([-Wno-pragmas])])
 240
 241          AS_IF([test "$CXX" = "clang++"],[_APPEND_COMPILE_FLAGS_ERROR([-Qunused-arguments])])
 242
 243          _APPEND_COMPILE_FLAGS_ERROR([-Wall])
 244          _APPEND_COMPILE_FLAGS_ERROR([-Wextra])
 245          _APPEND_COMPILE_FLAGS_ERROR([-Weverything])
 246          _APPEND_COMPILE_FLAGS_ERROR([-Wthis-test-should-fail])
 247 # Anything below this comment please keep sorted.
 248 # _APPEND_COMPILE_FLAGS_ERROR([-Wmissing-format-attribute])
 249           _APPEND_COMPILE_FLAGS_ERROR([-Wno-attributes])
 250           _APPEND_COMPILE_FLAGS_ERROR([-Wvarargs])
 251           _APPEND_COMPILE_FLAGS_ERROR([-Waddress])
 252           _APPEND_COMPILE_FLAGS_ERROR([-Warray-bounds])
 253           _APPEND_COMPILE_FLAGS_ERROR([-Wchar-subscripts])
 254           _APPEND_COMPILE_FLAGS_ERROR([-Wcomment])
 255           _APPEND_COMPILE_FLAGS_ERROR([-Wctor-dtor-privacy])
 256           _APPEND_COMPILE_FLAGS_ERROR([-Wfloat-equal])
 257           _APPEND_COMPILE_FLAGS_ERROR([-Wformat=2])
 258           _APPEND_COMPILE_FLAGS_ERROR([-Wformat-y2k])
 259           _APPEND_COMPILE_FLAGS_ERROR([-Wmaybe-uninitialized])
 260           _APPEND_COMPILE_FLAGS_ERROR([-Wmissing-field-initializers])
 261           _APPEND_COMPILE_FLAGS_ERROR([-Wlogical-op])
 262           _APPEND_COMPILE_FLAGS_ERROR([-Wnon-virtual-dtor])
 263           _APPEND_COMPILE_FLAGS_ERROR([-Wnormalized=id])
 264           _APPEND_COMPILE_FLAGS_ERROR([-Woverloaded-virtual])
 265           _APPEND_COMPILE_FLAGS_ERROR([-Wpointer-arith])
 266           AS_IF([test "x$MINGW" = xyes],
 267                 [_APPEND_COMPILE_FLAGS_ERROR([-Wno-suggest-attribute=const])
 268                 _APPEND_COMPILE_FLAGS_ERROR([-Wno-missing-noreturn])
 269                 _APPEND_COMPILE_FLAGS_ERROR([-Wmissing-noreturn])
 270                 _APPEND_COMPILE_FLAGS_ERROR([-Wno-suggest-attribute=noreturn])
 271                 _APPEND_COMPILE_FLAGS_ERROR([-Wno-error=suggest-attribute=noreturn])
 272                 _APPEND_COMPILE_FLAGS_ERROR([-Wno-redundant-decls])],
 273                 [_APPEND_COMPILE_FLAGS_ERROR([-Wredundant-decls])])
 274           _APPEND_COMPILE_FLAGS_ERROR([-Wshadow])
 275           _APPEND_COMPILE_FLAGS_ERROR([-Wshorten-64-to-32])
 276           _APPEND_COMPILE_FLAGS_ERROR([-Wsign-compare])
 277           _APPEND_COMPILE_FLAGS_ERROR([-Wstrict-overflow=1])
 278           _APPEND_COMPILE_FLAGS_ERROR([-Wswitch-enum])
 279           _APPEND_COMPILE_FLAGS_ERROR([-Wtrampolines])
 280           _APPEND_COMPILE_FLAGS_ERROR([-Wundef])
 281           _APPEND_COMPILE_FLAGS_ERROR([-Wunsafe-loop-optimizations])
 282           _APPEND_COMPILE_FLAGS_ERROR([-funsafe-loop-optimizations])
 283           _APPEND_COMPILE_FLAGS_ERROR([-Wc++11-compat])
 284           _APPEND_COMPILE_FLAGS_ERROR([-Weffc++])
 285           AS_IF([test "x$MINGW" != xyes],[
 286             AS_IF([test "x$ac_cv_vcs_checkout" = xyes],[
 287               AS_IF([test "x$enable_shared" = "xyes"],[
 288                 _APPEND_COMPILE_FLAGS_ERROR([-fno-omit-frame-pointer])
 289                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=address])
 290                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=integer])
 291                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=thread])
 292                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=memory])
 293                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=alignment])
 294                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=bool])
 295                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=bounds])
 296                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=enum])
 297                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=float-cast-overflow])
 298                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=float-divide-by-zero])
 299                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=integer-divide-by-zero])
 300                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=null])
 301                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=object-size])
 302                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=return])
 303                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=shift])
 304                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=signed-integer-overflow])
 305                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=unreachable])
 306                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=unsigned-integer-overflow])
 307                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=vla-bound])
 308                 _APPEND_COMPILE_FLAGS_ERROR([-fsanitize=vptr])
 309               ])
 310             ])
 311           ])
 312           _APPEND_COMPILE_FLAGS_ERROR([-Wold-style-cast])
 313           _APPEND_COMPILE_FLAGS_ERROR([-Wclobbered])
 314           _APPEND_COMPILE_FLAGS_ERROR([-Wunused])
 315           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-result])
 316           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-variable])
 317           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-parameter])
 318           _APPEND_COMPILE_FLAGS_ERROR([-Wunused-local-typedefs])
 319           _APPEND_COMPILE_FLAGS_ERROR([-Wwrite-strings])
 320           _APPEND_COMPILE_FLAGS_ERROR([-Wformat-security])
 321           _APPEND_COMPILE_FLAGS_ERROR([-floop-parallelize-all])
 322           _APPEND_COMPILE_FLAGS_ERROR([-fwrapv])
 323           _APPEND_COMPILE_FLAGS_ERROR([-fmudflapt])
 324           _APPEND_COMPILE_FLAGS_ERROR([-pipe])
 325           _APPEND_COMPILE_FLAGS_ERROR([-fPIE -pie])
 326           _APPEND_COMPILE_FLAGS_ERROR([-Wsizeof-pointer-memaccess])
 327           _APPEND_COMPILE_FLAGS_ERROR([-Wpacked])
 328           _APPEND_COMPILE_FLAGS_ERROR([-Wlong-long])
 329           _APPEND_COMPILE_FLAGS_ERROR([-Wunreachable-code])
 330
 331           AS_IF([test "x$ax_enable_debug" = xno],
 332           [AS_IF([test "x$ac_cv_vcs_checkout" = xyes],
 333             [AS_IF([test "x${target_os}" != "xmingw"],
 334               [AS_IF([test "x$ac_c_gcc_recent" = xyes],
 335                 [_APPEND_COMPILE_FLAGS_ERROR([-D_FORTIFY_SOURCE=2])
 336                 #_APPEND_COMPILE_FLAGS_ERROR([-Wstack-protector])
 337                 #_APPEND_COMPILE_FLAGS_ERROR([-fstack-protector --param=ssp-buffer-size=4])
 338                 _APPEND_COMPILE_FLAGS_ERROR([-fstack-protector-all])
 339                 ])])])])
 340
 341           AS_IF([test "x$ac_cv_warnings_as_errors" = xyes],
 342                 [AX_APPEND_FLAG([-Werror])])
 343           AC_LANG_POP([C++])
 344   ])
 345
 346 # All of the heavy lifting happens in _HARDEN_LINKER_FLAGS,
 347 # _HARDEN_CC_COMPILER_FLAGS, _HARDEN_CXX_COMPILER_FLAGS
 348   AC_DEFUN([AX_HARDEN_COMPILER_FLAGS],
 349            [AC_PREREQ([2.63])dnl
 350            AC_REQUIRE([_WARNINGS_AS_ERRORS])
 351            AC_REQUIRE([AX_APPEND_LINK_FLAGS])
 352            AC_REQUIRE([AX_COMPILER_VERSION])
 353            AC_REQUIRE([AX_DEBUG])
 354            AC_REQUIRE([AX_VCS_CHECKOUT])
 355
 356            AC_REQUIRE([gl_VISIBILITY])
 357            AS_IF([test -n "$CFLAG_VISIBILITY"],[CPPFLAGS="$CPPFLAGS $CFLAG_VISIBILITY"])
 358
 359            AC_REQUIRE([_HARDEN_LINKER_FLAGS])
 360            AC_REQUIRE([_HARDEN_CC_COMPILER_FLAGS])
 361            AC_REQUIRE([_HARDEN_CXX_COMPILER_FLAGS])
 362            ])