message: autoconf: Sane --enable-debug defaults.
  Don't optimize at all when --enable-debug is supplied. This makes sure
  that nothing is optimized out.
diff: @@ -239,7 +239,7 @@ AM_CONDITIONAL(ENABLE_MAN, test "$enable_man" != no)
  # Enable debug
  AC_ARG_ENABLE([debug],
  [AS_HELP_STRING([--enable-debug],
  - [use debug compiler flags and macros (default is no)])],
  + [use compiler flags and macros suited for debugging (default is no)])],
  [enable_debug=$enableval],
  [enable_debug=no])
  @@ -271,12 +271,9 @@ if test "x$enable_debug" = xyes; then
  if test "x$CXXFLAGS_overridden" = xno; then
  CXXFLAGS=""
  fi
  - # Prefer -Og, fall back to -O0 if that is unavailable.
  - AX_CHECK_COMPILE_FLAG(
  - [-Og],
  - [[DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -Og"]],
  - [AX_CHECK_COMPILE_FLAG([-O0],[[DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -O0"]],,[[$CXXFLAG_WERROR]])],
  - [[$CXXFLAG_WERROR]])
  +
  + # Disable all optimizations
  + AX_CHECK_COMPILE_FLAG([-O0], [[DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -O0"]],,[[$CXXFLAG_WERROR]])
  # Prefer -g3, fall back to -g if that is unavailable.
  AX_CHECK_COMPILE_FLAG(
  