From 5e3a02a8342c0c5525e42a54d49670201fcd5ecb Mon Sep 17 00:00:00 2001
From: Alex Crane <crane@jazznetworks.com>
Date: Wed, 27 Mar 2019 18:53:23 +0000
Subject: [PATCH] Fix starlight-go issue #18 by returning an error if passed
 type isnt convertible to expected type

---
 convert/conv.go | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/convert/conv.go b/convert/conv.go
index a6f41c3..99a39a0 100644
--- a/convert/conv.go
+++ b/convert/conv.go
@@ -291,6 +291,9 @@ func makeStarFn(name string, gofn reflect.Value) *starlark.Builtin {
 			val := reflect.ValueOf(v)
 			argT := gofn.Type().In(i)
 			if !val.Type().AssignableTo(argT) {
+				if !val.Type().ConvertibleTo(argT) {
+					return starlark.None, fmt.Errorf("arg %d expected type %v got %v", i, argT, val.Type())
+				}
 				val = val.Convert(argT)
 			}
 			rvs = append(rvs, val)
@@ -345,6 +348,9 @@ func makeVariadicStarFn(name string, gofn reflect.Value) *starlark.Builtin {
 			val := reflect.ValueOf(vals[i])
 			argT := gofn.Type().In(i)
 			if !val.Type().AssignableTo(argT) {
+				if !val.Type().ConvertibleTo(argT) {
+					return starlark.None, fmt.Errorf("arg %d expected type %v got %v", i, argT, val.Type())
+				}
 				val = val.Convert(argT)
 			}
 			rvs = append(rvs, val)
@@ -356,6 +362,9 @@ func makeVariadicStarFn(name string, gofn reflect.Value) *starlark.Builtin {
 		for i := minArgs; i < len(vals); i++ {
 			val := reflect.ValueOf(vals[i])
 			if !val.Type().AssignableTo(vtype) {
+				if !val.Type().ConvertibleTo(vtype) {
+					return starlark.None, fmt.Errorf("arg %d expected type %v got %v", i, vtype, val.Type())
+				}
 				val = val.Convert(vtype)
 			}
 			rvs = append(rvs, val)