c++17 u8 character literals testcase

Examples/test-suite/common.mk

@@ -164,6 +164,7 @@ CPP_TEST_CASES += \
 	cpp_typedef \
 	cpp17_nested_namespaces \
 	cpp17_nspace_nested_namespaces \
+	cpp17_u8_char_literals \
 	curiously_recurring_template_pattern \
 	default_args \
 	default_arg_expressions \

Examples/test-suite/cpp17_u8_char_literals.i

@@ -1,8 +1,26 @@
 %module cpp17_u8_char_literals
 
-%inline %{
+// Tests are designed so that code compiles with C++98 compilers
+
+%{
+#if __cplusplus >= 201703L
+#define CPP17 1
+#endif
+%}
+
 // UTF-8 character literals will (apparently) have type char8_t in C++20.
 char a = u8'a';
 char u = u8'u';
 char u8 = u8'8';
+
+%{
+#if defined(CPP17)
+char a = u8'a';
+char u = u8'u';
+char u8 = u8'8';
+#else
+char a = 'a';
+char u = 'u';
+char u8 = '8';
+#endif
 %}