fix: improve setting results in multiple output functions

_test/fun19.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+)
+
+func foo() ([]string, error) {
+	return nil, fmt.Errorf("bar")
+}
+
+func main() {
+	a, b := foo()
+	fmt.Println(a, b)
+}
+
+// Output:
+// [] bar

_test/fun20.go

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+var myerr error = fmt.Errorf("bar")
+
+func ferr() error { return myerr }
+
+func foo() ([]string, error) {
+	return nil, ferr()
+}
+
+func main() {
+	a, b := foo()
+	fmt.Println(a, b)
+}
+
+// Output:
+// [] bar

interp/cfg.go

@@ -823,12 +823,16 @@ func (interp *Interpreter) cfg(root *node, pkgID string) ([]*node, error) {
 						}
 					} else {
 						n.typ = &itype{cat: valueT, rtype: typ.Out(0)}
+						if n.anc.kind == returnStmt {
+							n.findex = childPos(n)
+						} else {
 							n.findex = sc.add(n.typ)
 							for i := 1; i < typ.NumOut(); i++ {
 								sc.add(&itype{cat: valueT, rtype: typ.Out(i)})
 							}
 						}
 					}
+				}
 			default:
 				if n.child[0].action == aGetFunc {
 					// Allocate a frame entry to store the anonymous function definition.
@@ -836,10 +840,14 @@ func (interp *Interpreter) cfg(root *node, pkgID string) ([]*node, error) {
 				}
 				if typ := n.child[0].typ; len(typ.ret) > 0 {
 					n.typ = typ.ret[0]
+					if n.anc.kind == returnStmt {
+						n.findex = childPos(n)
+					} else {
 						n.findex = sc.add(n.typ)
 						for _, t := range typ.ret[1:] {
 							sc.add(t)
 						}
+					}
 				} else {
 					n.findex = -1
 				}

interp/run.go

@@ -687,7 +687,7 @@ func call(n *node) {
 	case returnStmt:
 		// Function call from a return statement: forward return values (always at frame start).
 		for i := range rtypes {
-			j := i
+			j := n.findex + i
 			ret := n.child[0].typ.ret[i]
 			callret := n.anc.val.(*node).typ.ret[i]
 			if callret.cat == interfaceT && ret.cat != interfaceT {
@@ -983,6 +983,7 @@ func callBin(n *node) {
 		case aReturn:
 			// The function call is part of a return statement, store output results
 			// directly in the frame location of outputs of the current function.
+			b := childPos(n)
 			n.exec = func(f *frame) bltn {
 				in := make([]reflect.Value, l)
 				for i, v := range values {
@@ -990,7 +991,7 @@ func callBin(n *node) {
 				}
 				out := value(f).Call(in)
 				for i, v := range out {
-					f.data[i].Set(v)
+					f.data[b+i].Set(v)
 				}
 				return tnext
 			}