fix: ensure type computation in ValueSpec statement (#64)

Use nodeType in global var declaration to infer the type,
otherwise it may not be set properly, and failure will occur at use of variable.

_test/closure7.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"fmt"
+)
+
+type Config struct {
+	A string
+}
+
+var conf *Config
+
+func SetConfig() func(*Config) {
+	return func(cf *Config) {
+		conf = cf
+	}
+}
+
+func main() {
+	conf := &Config{
+		A: "foo",
+	}
+
+	fmt.Println(conf.A)
+}
+
+// Output:
+// foo

interp/cfg.go

@@ -949,7 +949,10 @@ func (interp *Interpreter) Cfg(root *Node) ([]*Node, error) {
 		case ValueSpec:
 			l := len(n.child) - 1
 			if n.typ = n.child[l].typ; n.typ == nil {
-				n.typ = scope.getType(n.child[l].ident)
+				n.typ, err = nodeType(interp, scope, n.child[l])
+				if err != nil {
+					return
+				}
 			}
 			for _, c := range n.child[:l] {
 				c.typ = n.typ

interp/interp_test.go

@@ -1367,6 +1367,45 @@ func main() {
 	// 9
 }
 
+func Example_closure7() {
+	src := `
+package main
+
+import (
+	"fmt"
+)
+
+type Config struct {
+	A string
+}
+
+var conf *Config
+
+func SetConfig() func(*Config) {
+	return func(cf *Config) {
+		conf = cf
+	}
+}
+
+func main() {
+	conf := &Config{
+		A: "foo",
+	}
+
+	fmt.Println(conf.A)
+}
+`
+	i := interp.New(interp.Opt{Entry: "main"})
+	i.Use(stdlib.Value, stdlib.Type)
+	_, err := i.Eval(src)
+	if err != nil {
+		panic(err)
+	}
+
+	// Output:
+	// foo
+}
+
 func Example_comp0() {
 	src := `
 package main