Can haz next revision of C++ standard.

mesonbuild/compilers.py

@@ -1688,7 +1688,7 @@ class GnuCPPCompiler(CPPCompiler):
 
     def get_options(self):
         opts = {'cpp_std' : coredata.UserComboOption('cpp_std', 'C++ language standard to use',
-                                                     ['none', 'c++03', 'c++11', 'c++14'],
+                                                     ['none', 'c++03', 'c++11', 'c++14', 'c++1z'],
                                                      'none'),
                 'cpp_debugstl': coredata.UserBooleanOption('cpp_debugstl',
                                                            'STL debug mode',
@@ -1743,7 +1743,7 @@ class ClangCPPCompiler(CPPCompiler):
 
     def get_options(self):
         return {'cpp_std' : coredata.UserComboOption('cpp_std', 'C++ language standard to use',
-                                                   ['none', 'c++03', 'c++11', 'c++14'],
+                                                   ['none', 'c++03', 'c++11', 'c++14', 'c++1z'],
                                                    'none')}
 
     def get_option_compile_args(self, options):