+dnl Usage: LYX_LIB_STDCXX: set lyx_cv_lib_stdcxx to yes if the STL library is libstdc++.
+AC_DEFUN([LYX_LIB_STDCXX],
+[AC_CACHE_CHECK([whether STL is libstdc++],
+ [lyx_cv_lib_stdcxx],
+[AC_TRY_COMPILE([#include<vector>], [
+#if ! defined(__GLIBCXX__) && ! defined(__GLIBCPP__)
+ this is not libstdc++
+#endif
+],
+[lyx_cv_lib_stdcxx=yes], [lyx_cv_lib_stdcxx=no])])
+])
+
+
+dnl Usage: LYX_LIB_STDCXX_CXX11_ABI: set lyx_cv_lib_stdcxx_cxx11_abi to yes
+dnl if the STL library is GNU libstdc++ and the C++11 ABI is used.
+AC_DEFUN([LYX_LIB_STDCXX_CXX11_ABI],
+[AC_CACHE_CHECK([whether STL is libstdc++ using the C++11 ABI],
+ [lyx_cv_lib_stdcxx_cxx11_abi],
+[AC_TRY_COMPILE([#include<vector>], [
+#if ! defined(_GLIBCXX_USE_CXX11_ABI) || ! _GLIBCXX_USE_CXX11_ABI
+ this is not libstdc++ using the C++11 ABI
+#endif
+],
+[lyx_cv_lib_stdcxx_cxx11_abi=yes], [lyx_cv_lib_stdcxx_cxx11_abi=no])])
+])
+
+
+AC_DEFUN([LYX_PROG_CXX],
+[AC_REQUIRE([AC_PROG_CXX])
+AC_REQUIRE([AC_PROG_CXXCPP])
+
+AC_LANG_PUSH(C++)
+LYX_PROG_CLANG
+LYX_LIB_STDCXX
+LYX_LIB_STDCXX_CXX11_ABI
+AC_LANG_POP(C++)
+
+if test $lyx_cv_lib_stdcxx = "yes" ; then
+ if test $lyx_cv_lib_stdcxx_cxx11_abi = "yes" ; then
+ AC_DEFINE(USE_GLIBCXX_CXX11_ABI, 1, [use GNU libstdc++ with C++11 ABI])
+ else
+ AC_DEFINE(STD_STRING_USES_COW, 1, [std::string uses copy-on-write])
+ fi
+else
+ if test $lyx_cv_prog_clang = "yes" ; then
+ AC_DEFINE(USE_LLVM_LIBCPP, 1, [use libc++ provided by llvm instead of GNU libstdc++])
+ fi
+fi