Use enum for builtin types

src/cpp_type.cpp

@@ -12,6 +12,67 @@
 
 using namespace cppast;
 
+const char* cppast::to_string(cpp_builtin_type_kind kind) noexcept
+{
+    switch (kind)
+    {
+    case cpp_void:
+        return "void";
+
+    case cpp_bool:
+        return "bool";
+
+    case cpp_uchar:
+        return "unsigned char";
+    case cpp_ushort:
+        return "unsigned short";
+    case cpp_uint:
+        return "unsigned int";
+    case cpp_ulong:
+        return "unsigned long";
+    case cpp_ulonglong:
+        return "unsigned long long";
+    case cpp_uint128:
+        return "unsigned __int128";
+
+    case cpp_schar:
+        return "signed char";
+    case cpp_short:
+        return "short";
+    case cpp_int:
+        return "int";
+    case cpp_long:
+        return "long";
+    case cpp_longlong:
+        return "long long";
+    case cpp_int128:
+        return "__int128";
+
+    case cpp_float:
+        return "float";
+    case cpp_double:
+        return "double";
+    case cpp_longdouble:
+        return "long double";
+    case cpp_float128:
+        return "__float128";
+
+    case cpp_char:
+        return "char";
+    case cpp_wchar:
+        return "wchar_t";
+    case cpp_char16:
+        return "char16_t";
+    case cpp_char32:
+        return "char32_t";
+
+    case cpp_nullptr:
+        return "std::nullptr_t";
+    }
+    DEBUG_UNREACHABLE(detail::assert_handler{});
+    return "__ups";
+}
+
 bool detail::cpp_type_ref_predicate::operator()(const cpp_entity& e)
 {
     return is_type(e.kind());