Prefer c++11 or c++0x to make GCC 4.6 happy

build/autotools/configure.ac

@@ -27,6 +27,10 @@ AC_CACHE_SAVE
 # Speedup compile
 EGG_CHECK_CCWALL
 EGG_CHECK_CCPIPE
+AX_CXX_COMPILE_STDCXX_11([noext], [optional])
+if [[ "${HAVE_CXX11}" -eq 0 ]]; then
+  CXX_FLAG_CHECK([CXXFLAGS], [-std=c++0x], [cxx0x])
+fi
 CXX_FLAG_CHECK([CXXFLAGS], [-fcolor-diagnostics], [colordiagnostics])
 #CXX_FLAG_CHECK([CXXFLAGS], [-Qunused-arguments], [unusedarguments])
 CXX_FLAG_CHECK([CXXFLAGS], [-Wno-invalid-source-encoding], [invalid_source_encoding])

build/autotools/includes/ax_cxx_compile_stdcxx_11.m4

@@ -0,0 +1,165 @@
+# ============================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
+# ============================================================================
+#
+# SYNOPSIS
+#
+#   AX_CXX_COMPILE_STDCXX_11([ext|noext],[mandatory|optional])
+#
+# DESCRIPTION
+#
+#   Check for baseline language coverage in the compiler for the C++11
+#   standard; if necessary, add switches to CXXFLAGS to enable support.
+#
+#   The first argument, if specified, indicates whether you insist on an
+#   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
+#   -std=c++11).  If neither is specified, you get whatever works, with
+#   preference for an extended mode.
+#
+#   The second argument, if specified 'mandatory' or if left unspecified,
+#   indicates that baseline C++11 support is required and that the macro
+#   should error out if no mode with that support is found.  If specified
+#   'optional', then configuration proceeds regardless, after defining
+#   HAVE_CXX11 if and only if a supporting mode is found.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
+#   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
+#   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
+#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
+#
+#   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
+
+m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
+  template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+    struct Base {
+    virtual void f() {}
+    };
+    struct Child : public Base {
+    virtual void f() override {}
+    };
+
+    typedef check<check<bool>> right_angle_brackets;
+
+    int a;
+    decltype(a) b;
+
+    typedef check<int> check_type;
+    check_type c;
+    check_type&& cr = static_cast<check_type&&>(c);
+
+    auto d = a;
+    auto l = [](){};
+    // Prevent Clang error: unused variable 'l' [-Werror,-Wunused-variable]
+    struct use_l { use_l() { l(); } };
+
+    // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+    // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function because of this
+    namespace test_template_alias_sfinae {
+        struct foo {};
+
+        template<typename T>
+        using member = typename T::member_type;
+
+        template<typename T>
+        void func(...) {}
+
+        template<typename T>
+        void func(member<T>*) {}
+
+        void test();
+
+        void test() {
+            func<foo>(0);
+        }
+    }
+]])
+
+AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl
+  m4_if([$1], [], [],
+        [$1], [ext], [],
+        [$1], [noext], [],
+        [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_11])])dnl
+  m4_if([$2], [], [ax_cxx_compile_cxx11_required=true],
+        [$2], [mandatory], [ax_cxx_compile_cxx11_required=true],
+        [$2], [optional], [ax_cxx_compile_cxx11_required=false],
+        [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])])
+  AC_LANG_PUSH([C++])dnl
+  ac_success=no
+  AC_CACHE_CHECK(whether $CXX supports C++11 features by default,
+  ax_cv_cxx_compile_cxx11,
+  [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
+    [ax_cv_cxx_compile_cxx11=yes],
+    [ax_cv_cxx_compile_cxx11=no])])
+  if test x$ax_cv_cxx_compile_cxx11 = xyes; then
+    ac_success=yes
+  fi
+
+  m4_if([$1], [noext], [], [dnl
+  if test x$ac_success = xno; then
+    for switch in -std=gnu++11 -std=gnu++0x; do
+      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
+      AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
+                     $cachevar,
+        [ac_save_CXXFLAGS="$CXXFLAGS"
+         CXXFLAGS="$CXXFLAGS $switch"
+         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
+          [eval $cachevar=yes],
+          [eval $cachevar=no])
+         CXXFLAGS="$ac_save_CXXFLAGS"])
+      if eval test x\$$cachevar = xyes; then
+        CXXFLAGS="$CXXFLAGS $switch"
+        ac_success=yes
+        break
+      fi
+    done
+  fi])
+
+  m4_if([$1], [ext], [], [dnl
+  if test x$ac_success = xno; then
+    for switch in -std=c++11 -std=c++0x; do
+      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
+      AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
+                     $cachevar,
+        [ac_save_CXXFLAGS="$CXXFLAGS"
+         CXXFLAGS="$CXXFLAGS $switch"
+         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])],
+          [eval $cachevar=yes],
+          [eval $cachevar=no])
+         CXXFLAGS="$ac_save_CXXFLAGS"])
+      if eval test x\$$cachevar = xyes; then
+        CXXFLAGS="$CXXFLAGS $switch"
+        ac_success=yes
+        break
+      fi
+    done
+  fi])
+  AC_LANG_POP([C++])
+  if test x$ax_cxx_compile_cxx11_required = xtrue; then
+    if test x$ac_success = xno; then
+      AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.])
+    fi
+  else
+    if test x$ac_success = xno; then
+      HAVE_CXX11=0
+      AC_MSG_NOTICE([No compiler with C++11 support was found])
+    else
+      HAVE_CXX11=1
+      AC_DEFINE(HAVE_CXX11,1,
+                [define if the compiler supports basic C++11 syntax])
+    fi
+
+    AC_SUBST(HAVE_CXX11)
+  fi
+])

configure

@@ -661,6 +661,7 @@ GCC3DEB
 GCC3_CXXFLAGS
 GCC3_CFLAGS
 CCDEPMODE
+HAVE_CXX11
 CC
 OBJEXT
 EXEEXT
@@ -3168,6 +3169,249 @@ $as_echo "$egg_cv_var_ccpipe" >&6; }
     fi
   fi
 
+    ax_cxx_compile_cxx11_required=false
+  ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+  ac_success=no
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
+$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
+if ${ax_cv_cxx_compile_cxx11+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat build/confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end build/confdefs.h.  */
+
+  template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+    struct Base {
+    virtual void f() {}
+    };
+    struct Child : public Base {
+    virtual void f() override {}
+    };
+
+    typedef check<check<bool>> right_angle_brackets;
+
+    int a;
+    decltype(a) b;
+
+    typedef check<int> check_type;
+    check_type c;
+    check_type&& cr = static_cast<check_type&&>(c);
+
+    auto d = a;
+    auto l = [](){};
+    // Prevent Clang error: unused variable 'l' [-Werror,-Wunused-variable]
+    struct use_l { use_l() { l(); } };
+
+    // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+    // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function because of this
+    namespace test_template_alias_sfinae {
+        struct foo {};
+
+        template<typename T>
+        using member = typename T::member_type;
+
+        template<typename T>
+        void func(...) {}
+
+        template<typename T>
+        void func(member<T>*) {}
+
+        void test();
+
+        void test() {
+            func<foo>(0);
+        }
+    }
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ax_cv_cxx_compile_cxx11=yes
+else
+  ax_cv_cxx_compile_cxx11=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
+$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
+  if test x$ax_cv_cxx_compile_cxx11 = xyes; then
+    ac_success=yes
+  fi
+
+
+
+    if test x$ac_success = xno; then
+    for switch in -std=c++11 -std=c++0x; do
+      cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
+if eval \${$cachevar+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_save_CXXFLAGS="$CXXFLAGS"
+         CXXFLAGS="$CXXFLAGS $switch"
+         cat build/confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end build/confdefs.h.  */
+
+  template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+    struct Base {
+    virtual void f() {}
+    };
+    struct Child : public Base {
+    virtual void f() override {}
+    };
+
+    typedef check<check<bool>> right_angle_brackets;
+
+    int a;
+    decltype(a) b;
+
+    typedef check<int> check_type;
+    check_type c;
+    check_type&& cr = static_cast<check_type&&>(c);
+
+    auto d = a;
+    auto l = [](){};
+    // Prevent Clang error: unused variable 'l' [-Werror,-Wunused-variable]
+    struct use_l { use_l() { l(); } };
+
+    // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+    // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function because of this
+    namespace test_template_alias_sfinae {
+        struct foo {};
+
+        template<typename T>
+        using member = typename T::member_type;
+
+        template<typename T>
+        void func(...) {}
+
+        template<typename T>
+        void func(member<T>*) {}
+
+        void test();
+
+        void test() {
+            func<foo>(0);
+        }
+    }
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  eval $cachevar=yes
+else
+  eval $cachevar=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+         CXXFLAGS="$ac_save_CXXFLAGS"
+fi
+eval ac_res=\$$cachevar
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+      if eval test x\$$cachevar = xyes; then
+        CXXFLAGS="$CXXFLAGS $switch"
+        ac_success=yes
+        break
+      fi
+    done
+  fi
+  ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+  if test x$ax_cxx_compile_cxx11_required = xtrue; then
+    if test x$ac_success = xno; then
+      as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5
+    fi
+  else
+    if test x$ac_success = xno; then
+      HAVE_CXX11=0
+      { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5
+$as_echo "$as_me: No compiler with C++11 support was found" >&6;}
+    else
+      HAVE_CXX11=1
+
+$as_echo "#define HAVE_CXX11 1" >>build/confdefs.h
+
+    fi
+
+
+  fi
+
+if [ "${HAVE_CXX11}" -eq 0 ]; then
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler understands -std=c++0x" >&5
+$as_echo_n "checking whether the compiler understands -std=c++0x... " >&6; }
+if ${ax_cv_prog_cc_cxx0x+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+    ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+    ac_saved_flags="$CXXFLAGS"
+    CXXFLAGS="-Werror -std=c++0x"
+    cat build/confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end build/confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ax_cv_prog_cc_cxx0x="yes"
+else
+  ax_cv_prog_cc_cxx0x="no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+    CXXFLAGS="$ac_saved_flags"
+    ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_prog_cc_cxx0x" >&5
+$as_echo "$ax_cv_prog_cc_cxx0x" >&6; }
+
+  if [ "$ax_cv_prog_cc_cxx0x" = "yes" ]; then
+    CXXFLAGS="$CXXFLAGS -std=c++0x"
+  elif [ -n "" ]; then
+      cat << 'EOF' >&2
+configure: error:
+
+  Your OS or C++ compiler does not support -std=c++0x.
+  This compile flag is required.
+
+EOF
+    exit 1
+  fi
+
+fi
 
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler understands -fcolor-diagnostics" >&5
 $as_echo_n "checking whether the compiler understands -fcolor-diagnostics... " >&6; }

src/config.h.in

@@ -25,6 +25,9 @@
 /* Define to 1 if you have the <arpa/inet.h> header file. */
 #undef HAVE_ARPA_INET_H
 
+/* define if the compiler supports basic C++11 syntax */
+#undef HAVE_CXX11
+
 /* Define to 1 if you have the declaration of `tzname', and to 0 if you don't.
    */
 #undef HAVE_DECL_TZNAME