+dnl Usage: LYX_PROG_CLANG: set lyx_cv_prog_clang to yes if the compiler is clang.
+AC_DEFUN([LYX_PROG_CLANG],
+[AC_CACHE_CHECK([whether the compiler is clang],
+ [lyx_cv_prog_clang],
+[AC_TRY_COMPILE([], [
+#ifndef __clang__
+ this is not clang
+#endif
+],
+[lyx_cv_prog_clang=yes ; CLANG=yes], [lyx_cv_prog_clang=no ; CLANG=no])])
+])
+
+
+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])])
+])
+
+