[Buildsystem] Require C++11-compliant compiler and clean up associated tests

As we have bumped our compiler requirements to GCC 4.4+, we can now
require the compiler to support C++11.

This patch updates both the autotools and the CMake tests to produce an
error if the compiler doesn't support either -std=c++11 or -std=c++0x.

It also renames the tests from ..0X to ..11 and renames the configure
options from --disable-gxx0xcheck to --disable-cxx11check and removes a
couple of redundant calls to the autotools macro.

cmake/modules/CheckCXX11Features.cmake

@@ -17,10 +17,10 @@ cmake_push_check_state()
 # test for C++11 flags
 include(TestCXXAcceptsFlag)
 
-if(NOT DISABLE_GXX0XCHECK)
+if(NOT DISABLE_CXX11CHECK)
   # try to use compiler flag -std=c++11
   check_cxx_accepts_flag("-std=c++11" CXX_FLAG_CXX11)
-endif(NOT DISABLE_GXX0XCHECK)
+endif(NOT DISABLE_CXX11CHECK)
 
 if(CXX_FLAG_CXX11)
   set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++11")
@@ -31,10 +31,13 @@ if(CXX_FLAG_CXX11)
   set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -std=c++11 ")
   set(CXX_STD11_FLAGS "-std=c++11")
 else()
-  if(NOT DISABLE_GXX0XCHECK)
+  if(NOT DISABLE_CXX11CHECK)
     # try to use compiler flag -std=c++0x for older compilers
     check_cxx_accepts_flag("-std=c++0x" CXX_FLAG_CXX0X)
-  endif(NOT DISABLE_GXX0XCHECK)
+    if(NOT CXX_FLAG_CXX0X)
+      MESSAGE(FATAL_ERROR "Your compiler does not seem to support C++11. If it does, please add any required flags to your CXXFLAGS and run dunecontrol with --disable-cxx11check")
+    endif(NOT CXX_FLAG_CXX0X)
+  endif(NOT DISABLE_CXX11CHECK)
   if(CXX_FLAG_CXX0X)
     set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++0x" )
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x ")

lib/dunecommonam2cmake.lib

@@ -28,10 +28,10 @@ dune_common_options_am2cmake()
     else
         CMAKE_PARAMS="$CMAKE_PARAMS -DUSE_MPI=ON"
     fi
-    # Check for --disable-gxx0xcheck
-    echo $PARAMS | grep \\-\\-disable-gxx0xcheck > /dev/null
+    # Check for --disable-cxx11check
+    echo $PARAMS | grep \\-\\-disable-cxx11check > /dev/null
     if test "$?" -eq 0 ; then
-        CMAKE_PARAMS="$CMAKE_PARAMS -DDISABLE_GXX0XCHECK:BOOL=TRUE"
+        CMAKE_PARAMS="$CMAKE_PARAMS -DDISABLE_CXX11CHECK:BOOL=TRUE"
     fi
 
     # Check for --disable-gxx0xcheck

m4/cxx0x_nullptr.m4

 AC_DEFUN([NULLPTR_CHECK],[
   AC_CACHE_CHECK([whether nullptr is supported], dune_cv_nullptr_support, [
     AC_REQUIRE([AC_PROG_CXX])
-    AC_REQUIRE([GXX0X])
+    AC_REQUIRE([CXX11])
     AC_LANG_PUSH([C++])
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
       [],[[

m4/cxx0x_compiler.m4 → m4/cxx11_compiler.m4

 # whether compiler accepts -std=c++11 or -std=c++0x
-# can be disabled by --disable-gxx0xcheck
+# can be disabled by --disable-cxx11check
+
+AC_DEFUN([CXX11],[
+  AC_REQUIRE([AC_PROG_CXX])
+  AC_ARG_ENABLE(cxx11check,
+    AC_HELP_STRING([--disable-cxx11check],
+      [Skip test whether compiler supports flag -std=c++11 and -std=c++0x to enable C++11 features
+       (Dune always requires C++11 support - if your compiler requires custom flags for C++11 mode, tell configure about them
+       in your CXXFLAGS and disable this check)]),
+      [cxx11check=$enableval],
+      [cxx11check=yes])
 
-AC_DEFUN([GXX0X],[
-  ac_save_CXX="$CXX"
-  
   # try flag -std=c++11
   AC_CACHE_CHECK([whether $CXX accepts -std=c++11], dune_cv_gplusplus_accepts_cplusplus11, [
-    AC_REQUIRE([AC_PROG_CXX])
-    AC_ARG_ENABLE(gxx0xcheck,
-      AC_HELP_STRING([--disable-gxx0xcheck],
-        [Skip test whether compiler supports flag -std=c++11 and -std=c++0x to enable C++11 features (with this option C++11 features will not be activated)]),
-        [gxx0xcheck=$enableval],
-        [gxx0xcheck=yes])
-    if test "x$GXX" = xyes && test "x$gxx0xcheck" = xyes; then
+    dune_cv_gplusplus_accepts_cplusplus11=no
+    if test "x$GXX" = xyes && test "x$cxx11check" = xyes; then
+      ac_save_CXX="$CXX"
       AC_LANG_PUSH([C++])
       CXX="$CXX -std=c++11"
       AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
@@ -22,18 +25,15 @@ AC_DEFUN([GXX0X],[
         dune_cv_gplusplus_accepts_cplusplus11=yes,
         dune_cv_gplusplus_accepts_cplusplus11=no)
       AC_LANG_POP([C++])
+      CXX="$ac_save_CXX"
     fi
   ])
-  if test "x$dune_cv_gplusplus_accepts_cplusplus11" == "xyes" ; then
-    CXX="$ac_save_CXX -std=c++11"
-    CXXCPP="$CXXCPP -std=c++11"
-  else
-    CXX="$ac_save_CXX"
-    
-    # try flag -std=c++0x instead
+  # try flag -std=c++0x
+  if test "x$dune_cv_gplusplus_accepts_cplusplus11" == "xno" ; then
     AC_CACHE_CHECK([whether $CXX accepts -std=c++0x], dune_cv_gplusplus_accepts_cplusplus0x, [
-      AC_REQUIRE([AC_PROG_CXX])
-      if test "x$GXX" = xyes && test "x$gxx0xcheck" = xyes; then
+      dune_cv_gplusplus_accepts_cplusplus0x=no
+      if test "x$GXX" = xyes && test "x$cxx11check" = xyes; then
+        ac_save_CXX="$CXX"
         AC_LANG_PUSH([C++])
         CXX="$CXX -std=c++0x"
         AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
@@ -43,13 +43,24 @@ AC_DEFUN([GXX0X],[
           dune_cv_gplusplus_accepts_cplusplus0x=yes,
           dune_cv_gplusplus_accepts_cplusplus0x=no)
         AC_LANG_POP([C++])
+        CXX="$ac_save_CXX"
       fi
     ])
-    if test "x$dune_cv_gplusplus_accepts_cplusplus0x" == "xyes" ; then
-      CXX="$ac_save_CXX -std=c++0x"
-      CXXCPP="$CXXCPP -std=c++0x"
+  fi
+
+  if test "x$dune_cv_gplusplus_accepts_cplusplus11" == "xyes" ; then
+    CXX="$CXX -std=c++11"
+    CXXCPP="$CXXCPP -std=c++11"
+  elif test "x$dune_cv_gplusplus_accepts_cplusplus0x" == "xyes" ; then
+    CXX="$CXX -std=c++0x"
+    CXXCPP="$CXXCPP -std=c++0x"
+  else
+    if test "x$cxx11check" = xyes; then
+      # we ran the test, and it failed - bail out
+      AC_MSG_FAILURE([Your compiler does not seem to support C++11!])
     else
-      CXX="$ac_save_CXX"
+      # test was skipped, warn the user
+      AC_MSG_WARN([Skipping test for C++11 support, make sure your compiler supports at least the feature set of GCC 4.4!])
     fi
   fi
 ])

m4/cxx11_constexpr.m4

@@ -4,7 +4,7 @@
 AC_DEFUN([CXX11_CONSTEXPR_CHECK],[
   AC_CACHE_CHECK([for C++11 constexpr], dune_cv_cxx11_constexpr_support, [
     AC_REQUIRE([AC_PROG_CXX])
-    AC_REQUIRE([GXX0X])
+    AC_REQUIRE([CXX11])
     AC_LANG_PUSH([C++])
     AC_COMPILE_IFELSE([
       AC_LANG_PROGRAM([

m4/dune_common.m4

@@ -18,7 +18,7 @@ AC_DEFUN([DUNE_COMMON_CHECKS],
   AC_REQUIRE([AC_PROG_MKDIR_P])
 
   AC_REQUIRE([DUNE_CHECK_COMPILER])
-  AC_REQUIRE([GXX0X])
+  AC_REQUIRE([CXX11])
   AC_REQUIRE([NULLPTR_CHECK])
   AC_REQUIRE([CXX11_CONSTEXPR_CHECK])
   AC_REQUIRE([DUNE_BOOST_BASE])