From f17e663493c80e2b9b9dbc8b6340c9239efc92a0 Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Thu, 23 Jul 2015 14:30:37 +0100
Subject: [PATCH] py: Issue an error when compiling Viper functions with more
 than 4 args.

Otherwise it can be very hard to track down bugs.
---
 py/emitnative.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/py/emitnative.c b/py/emitnative.c
index 0d3f78da4e..37dbd56b3e 100644
--- a/py/emitnative.c
+++ b/py/emitnative.c
@@ -675,6 +675,12 @@ STATIC void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
 
     if (emit->do_viper_types) {
 
+        // right now we have a restriction of maximum of 4 arguments
+        if (scope->num_pos_args >= 5) {
+            EMIT_NATIVE_VIPER_TYPE_ERROR(emit, "Viper functions don't currently support more than 4 arguments (while compiling '%q')", scope->simple_name); return;
+            return;
+        }
+
         // entry to function
         int num_locals = 0;
         if (pass > MP_PASS_SCOPE) {