disable C++17 tests when using C++14

test/test_templates.py

@@ -15,6 +15,11 @@ def setup_class(cls):
         import cppyy
         cls.templates = cppyy.load_reflection_info(cls.test_dct)
 
+        at_least_17 = 201402 < cppyy.gbl.gInterpreter.ProcessLine("__cplusplus;")
+        cls.has_integral_v    = at_least_17
+        cls.has_disjunction_v = at_least_17
+        cls.has_pack_fold     = at_least_17
+
     def test00_template_back_reference(self):
         """Template reflection"""
 
@@ -301,9 +306,10 @@ def test12_template_aliases(self):
             assert nsup.make_vector[int , 4]().m_val == 4
 
       # with inner types using
-        assert cppyy.gbl.gInterpreter.CheckClassTemplate("using_problem::Bar::Foo")
-        assert nsup.Foo
-        assert nsup.Bar.Foo       # used to fail
+        if cppyy.gbl.gInterpreter.ProcessLine("__cplusplus;") > 201402:
+            assert cppyy.gbl.gInterpreter.CheckClassTemplate("using_problem::Bar::Foo")
+            assert nsup.Foo
+            assert nsup.Bar.Foo        # used to fail
 
     def test13_using_templated_method(self):
         """Access to base class templated methods through 'using'"""
@@ -492,6 +498,9 @@ class CustomVec {
     def test20_templated_ctor_with_defaults(self):
         """Templated constructor with defaults used to be ignored"""
 
+        if not self.has_integral_v:
+            return
+
         import cppyy
 
         cppyy.cppdef("""\
@@ -724,6 +733,9 @@ def test26_partial_templates(self):
     def test27_variadic_constructor(self):
         """Use of variadic template function as contructor"""
 
+        if not self.has_disjunction_v:
+            return
+
         import cppyy
 
         cppyy.cppdef("""\
@@ -1128,6 +1140,9 @@ def test33_using_template_argument(self):
     def test34_cstring_template_argument(self):
         """`const char*` use over std::string"""
 
+        if not self.has_pack_fold:
+            return
+
         import cppyy
         import ctypes