Fix a case where a global symbol was overwritten

_test/map3.go

@@ -1,11 +1,8 @@
 package main
 
 func main() {
-	//dict := map[string]string{}
-	dict := map[string]string{"bidule": "machin", "truc": "bidule"}
-	//println(dict)
-	//dict["truc"] = "machin"
-	//println(dict)
+	dict := map[string]string{}
+	dict["truc"] = "machin"
 	println(dict["truc"])
 }
 

interp/cfg.go

@@ -690,11 +690,18 @@ func (interp *Interpreter) Cfg(root *Node) []*Node {
 		case Ident:
 			if isKey(n) {
 				// Skip symbol creation/lookup for idents used as key
-			} else if isFuncArg(n) || isNewDefine(n) {
-				// Create a new symbol in current scope, type to be set by parent node
+			} else if isFuncArg(n) {
 				n.findex = scope.inc(interp)
 				scope.sym[n.ident] = &Symbol{index: scope.size, kind: Var, global: scope.global}
 				n.sym = scope.sym[n.ident]
+			} else if isNewDefine(n) {
+				// Create a new symbol in current scope, type to be set by parent node
+				// Note that global symbol should already be defined (gta)
+				if _, _, ok := scope.lookup(n.ident); !ok && !scope.global {
+					n.findex = scope.inc(interp)
+					scope.sym[n.ident] = &Symbol{index: scope.size, kind: Var, global: scope.global}
+					n.sym = scope.sym[n.ident]
+				}
 			} else if sym, level, ok := scope.lookup(n.ident); ok {
 				// Found symbol, populate node info
 				n.typ, n.findex, n.level = sym.typ, sym.index, level

interp/interp_test.go

@@ -1549,11 +1549,8 @@ func Example_map3() {
 package main
 
 func main() {
-	//dict := map[string]string{}
-	dict := map[string]string{"bidule": "machin", "truc": "bidule"}
-	//println(dict)
-	//dict["truc"] = "machin"
-	//println(dict)
+	dict := map[string]string{}
+	dict["truc"] = "machin"
 	println(dict["truc"])
 }
 `
@@ -2437,6 +2434,24 @@ func main() {
 	// 1 2
 }
 
+func Example_ret4() {
+	src := `
+package main
+
+func r() int { return 1 }
+
+func main() {
+	a := r()
+	println(a)
+}
+`
+	i := NewInterpreter(Opt{Entry: "main"}, "ret4.go")
+	i.Eval(src)
+
+	// Output:
+	// 1
+}
+
 func Example_run0() {
 	src := `
 package main

interp/run.go

@@ -61,6 +61,7 @@ func (interp *Interpreter) run(n *Node, cf *Frame) {
 			f.data[i] = reflect.New(t).Elem()
 		}
 	}
+	//log.Println(n.index, "run", n.start.index)
 	runCfg(n.start, f)
 }