Convert primitives before passing to host language

This resolves an issue where we map unsigned primitives to their
signed variants, and occasionally pass the unsigned variant (which
is outside the bounds of the signed variant) to the host language.

In Java this can cause a panic as the VM sees an int outside the
range of a short (for example with network ports).

Author: TheBlueMatt

gen_type_mapping.py

@@ -260,11 +260,19 @@ def _do_map_type_with_info(self, ty_info, print_void, ret_arr_len, is_free, hold
                 return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
                     arg_conv = None, arg_conv_name = "arg", arg_conv_cleanup = None,
                     ret_conv = None, ret_conv_name = None, to_hu_conv = "TODO 8", to_hu_conv_name = None, from_hu_conv = None)
-        elif ty_info.is_native_primitive:
+        elif ty_info.is_native_primitive and ty_info.c_ty != "void":
             assert not is_nullable
             return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
-                arg_conv = None, arg_conv_name = ty_info.var_name, arg_conv_cleanup = None,
-                ret_conv = None, ret_conv_name = None, to_hu_conv = None, to_hu_conv_name = None, from_hu_conv = None)
+                arg_conv = None, arg_conv_name =  ty_info.var_name, arg_conv_cleanup = None,
+                ret_conv = (ty_info.c_ty + " " + ty_info.var_name + "_conv = ", ";"), ret_conv_name = ty_info.var_name + "_conv",
+                to_hu_conv = None, to_hu_conv_name = None, from_hu_conv = None)
+        elif ty_info.c_ty == "void":
+            assert ty_info.is_native_primitive
+            assert not is_nullable
+            return ConvInfo(ty_info = ty_info, arg_name = ty_info.var_name,
+                arg_conv = None, arg_conv_name =  ty_info.var_name, arg_conv_cleanup = None,
+                ret_conv = None, ret_conv_name = ty_info.var_name,
+                to_hu_conv = None, to_hu_conv_name = None, from_hu_conv = None)
         else:
             if ty_info.var_name == "":
                 ty_info.var_name = "ret"