fix: checks that value implements a binary type in type assert

_test/issue-558.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"strings"
+)
+
+type readAutoCloser struct {
+	r io.ReadCloser
+}
+
+func (a readAutoCloser) Read(b []byte) (n int, err error) {
+	if a.r == nil {
+		return 0, io.EOF
+	}
+	n, err = a.r.Read(b)
+	if err == io.EOF {
+		a.Close()
+	}
+	return n, err
+}
+
+func (a readAutoCloser) Close() error {
+	if a.r == nil {
+		return nil
+	}
+	return a.r.(io.Closer).Close()
+}
+
+type pipe struct {
+	Reader readAutoCloser
+}
+
+func newReadAutoCloser(r io.Reader) readAutoCloser {
+	if _, ok := r.(io.Closer); !ok {
+		return readAutoCloser{ioutil.NopCloser(r)}
+	}
+	return readAutoCloser{r.(io.ReadCloser)}
+}
+
+func main() {
+	p := &pipe{}
+	p.Reader = newReadAutoCloser(strings.NewReader("test"))
+	b, err := ioutil.ReadAll(p.Reader)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(string(b))
+}
+
+// Output:
+// test

_test/type20.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"io"
+	"strings"
+)
+
+func isCloser(r io.Reader) bool {
+	_, ok := r.(io.Closer)
+	return ok
+}
+
+func main() {
+	println(isCloser(strings.NewReader("test")))
+}
+
+// Output:
+// false

interp/run.go

@@ -121,56 +121,63 @@ func runCfg(n *node, f *frame) {
 }
 
 func typeAssertStatus(n *node) {
-	value := genValue(n.child[0])      // input value
+	c0, c1 := n.child[0], n.child[1]
+	value := genValue(c0)              // input value
 	value1 := genValue(n.anc.child[1]) // returned status
+	typ := c1.typ.rtype                // type to assert
 	next := getExec(n.tnext)
 
 	switch {
-	case n.child[0].typ.cat == valueT:
+	case c0.typ.cat == valueT:
 		n.exec = func(f *frame) bltn {
-			if !value(f).IsValid() || value(f).IsNil() {
+			v := value(f)
+			if !v.IsValid() || v.IsNil() {
 				value1(f).SetBool(false)
 			}
-			value1(f).SetBool(true)
+			value1(f).SetBool(v.Type().Implements(typ))
 			return next
 		}
-	case n.child[1].typ.cat == interfaceT:
+	case c1.typ.cat == interfaceT:
 		n.exec = func(f *frame) bltn {
 			_, ok := value(f).Interface().(valueInterface)
-			//value0(f).Set(reflect.ValueOf(valueInterface{v.node, v.value}))
+			// TODO: verify that value(f) implements asserted type.
 			value1(f).SetBool(ok)
 			return next
 		}
 	default:
 		n.exec = func(f *frame) bltn {
 			_, ok := value(f).Interface().(valueInterface)
-			//value0(f).Set(v.value)
+			// TODO: verify that value(f) implements asserted type.
 			value1(f).SetBool(ok)
 			return next
 		}
 	}
 }
 
 func typeAssert(n *node) {
-	value := genValue(n.child[0]) // input value
-	dest := genValue(n)           // returned result
+	c0, c1 := n.child[0], n.child[1]
+	value := genValue(c0) // input value
+	dest := genValue(n)   // returned result
 	next := getExec(n.tnext)
 
 	switch {
-	case n.child[0].typ.cat == valueT:
+	case c0.typ.cat == valueT:
 		n.exec = func(f *frame) bltn {
-			dest(f).Set(value(f).Elem())
+			v := value(f)
+			dest(f).Set(v.Elem())
 			return next
 		}
-	case n.child[1].typ.cat == interfaceT:
+	case c1.typ.cat == interfaceT:
 		n.exec = func(f *frame) bltn {
 			v := value(f).Interface().(valueInterface)
+			// TODO: verify that value(f) implements asserted type.
 			dest(f).Set(reflect.ValueOf(valueInterface{v.node, v.value}))
 			return next
 		}
 	default:
 		n.exec = func(f *frame) bltn {
 			v := value(f).Interface().(valueInterface)
+			// TODO: verify that value(f) implements asserted type.
 			dest(f).Set(v.value)
 			return next
 		}
@@ -195,13 +202,15 @@ func typeAssert2(n *node) {
 	case n.child[1].typ.cat == interfaceT:
 		n.exec = func(f *frame) bltn {
 			v, ok := value(f).Interface().(valueInterface)
+			// TODO: verify that value(f) implements asserted type.
 			value0(f).Set(reflect.ValueOf(valueInterface{v.node, v.value}))
 			value1(f).SetBool(ok)
 			return next
 		}
 	default:
 		n.exec = func(f *frame) bltn {
 			v, ok := value(f).Interface().(valueInterface)
+			// TODO: verify that value(f) implements asserted type.
 			value0(f).Set(v.value)
 			value1(f).SetBool(ok)
 			return next