interp: fix memory handling of global values

In some cases, the global character of a value was lost, leading to
undefined behaviour. Now a node level field of -1 means that the value
is global, and that it should be accessed from the root data frame.

Fixes #993.

.goreleaser.yml

@@ -45,3 +45,19 @@ archives:
         format: zip
     files:
       - LICENSE
+
+brews:
+  - github:
+      owner: traefik
+      name: homebrew-tap
+    commit_author:
+      name: traefiker
+      email: 30906710+traefiker@users.noreply.github.com
+    folder: Formula
+    homepage: https://github.com/traefik/yaegi
+    description: |
+      Yaegi is Another Elegant Go Interpreter.
+      It powers executable Go scripts and plugins, in embedded interpreters
+      or interactive shells, on top of the Go runtime.
+    test: |
+      system "#{bin}/yaegi version"

Makefile

@@ -16,12 +16,15 @@ internal/cmd/extract/extract:
 generate: gen_all_syscall
 	go generate
 
+install:
+	GOFLAGS=-ldflags=-X=main.version=$$(git describe --tags) go install ./...
+
 tests:
-	GO111MODULE=off go test -v ./...
-	GO111MODULE=off go test -race ./interp
+	go test -v ./...
+	go test -race ./interp
 
 # https://github.com/goreleaser/godownloader
 install.sh: .goreleaser.yml
 	godownloader --repo=traefik/yaegi -o install.sh .goreleaser.yml
 
-.PHONY: check gen_all_syscall gen_tests generate_downloader internal/cmd/extract/extract
+.PHONY: check gen_all_syscall gen_tests generate_downloader internal/cmd/extract/extract install

README.md

@@ -128,10 +128,20 @@ Hello World
 >
 ```
 
-Or interpret Go files:
+Note that in interactive mode, all stdlib package are pre-imported,
+you can use them directly:
 
 ```console
-$ yaegi cmd/yaegi/yaegi.go
+$ yaegi
+> reflect.TypeOf(time.Date)
+: func(int, time.Month, int, int, int, int, int, *time.Location) time.Time
+>
+```
+
+Or interpret Go packages, directories or files, including itself:
+
+```console
+$ yaegi -syscall -unsafe -unrestricted github.com/traefik/yaegi/cmd/yaegi
 >
 ```
 

_test/a43.go

@@ -0,0 +1,17 @@
+package main
+
+import "fmt"
+
+type T [l1 + l2]int
+
+const (
+	l1 = 2
+	l2 = 3
+)
+
+func main() {
+	fmt.Println(T{})
+}
+
+// Output:
+// [0 0 0 0 0]

_test/a44.go

@@ -0,0 +1,12 @@
+package main
+
+var a = [max]int{}
+
+const max = 32
+
+func main() {
+	println(len(a))
+}
+
+// Output:
+// 32

_test/addr1.go

@@ -0,0 +1,22 @@
+package main
+
+import "fmt"
+
+type T struct {
+	A int
+	B int
+}
+
+func main() {
+	a := &[]T{
+		{1, 2},
+		{3, 4},
+	}
+	fmt.Println("a:", a)
+	x := &(*a)[1:][0]
+	fmt.Println("x:", x)
+}
+
+// Output:
+// a: &[{1 2} {3 4}]
+// x: &{3 4}

_test/addr2.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"encoding/xml"
+	"fmt"
+)
+
+type Email struct {
+	Where string `xml:"where,attr"`
+	Addr  string
+}
+
+func f(s string, r interface{}) error {
+	return xml.Unmarshal([]byte(s), &r)
+}
+
+func main() {
+	data := `
+		<Email where='work'>
+			<Addr>bob@work.com</Addr>
+		</Email>
+	`
+	v := Email{}
+	err := f(data, &v)
+	fmt.Println(err, v)
+}
+
+// Ouput:
+// <nil> {work bob@work.com}

_test/append1.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+)
+
+func main() {
+	s := bufio.NewScanner(bytes.NewReader([]byte("Hello\nTest\nLine3")))
+	s.Scan()
+	println(string(append(s.Bytes(), []byte(" World")...)))
+}
+
+// Output:
+// Hello World

_test/append2.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+)
+
+func main() {
+	s := bufio.NewScanner(bytes.NewReader([]byte("Hello\nTest\nLine3")))
+	s.Scan()
+	println(string(append(s.Bytes(), " World"...)))
+}
+
+// Output:
+// Hello World

_test/assert0.go

@@ -0,0 +1,125 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"time"
+)
+
+type MyWriter interface {
+	Write(p []byte) (i int, err error)
+}
+
+type TestStruct struct{}
+
+func (t TestStruct) Write(p []byte) (n int, err error) {
+	return len(p), nil
+}
+
+func usesWriter(w MyWriter) {
+	n, _ := w.Write([]byte("hello world"))
+	fmt.Println(n)
+}
+
+type MyStringer interface {
+	String() string
+}
+
+func usesStringer(s MyStringer) {
+	fmt.Println(s.String())
+}
+
+func main() {
+	aType := reflect.TypeOf((*MyWriter)(nil)).Elem()
+
+	var t interface{}
+	t = TestStruct{}
+	var tw MyWriter
+	var ok bool
+	tw, ok = t.(MyWriter)
+	if !ok {
+		fmt.Println("TestStruct does not implement MyWriter")
+	} else {
+		fmt.Println("TestStruct implements MyWriter")
+		usesWriter(tw)
+	}
+	n, _ := t.(MyWriter).Write([]byte("hello world"))
+	fmt.Println(n)
+	bType := reflect.TypeOf(TestStruct{})
+	fmt.Println(bType.Implements(aType))
+
+	// not redundant with the above, because it goes through a slightly different code path.
+	if _, ok := t.(MyWriter); !ok {
+		fmt.Println("TestStruct does not implement MyWriter")
+		return
+	} else {
+		fmt.Println("TestStruct implements MyWriter")
+	}
+
+	t = 42
+	foo, ok := t.(MyWriter)
+	if !ok {
+		fmt.Println("42 does not implement MyWriter")
+	} else {
+		fmt.Println("42 implements MyWriter")
+	}
+	_ = foo
+
+	if _, ok := t.(MyWriter); !ok {
+		fmt.Println("42 does not implement MyWriter")
+	} else {
+		fmt.Println("42 implements MyWriter")
+	}
+
+	var tt interface{}
+	tt = time.Nanosecond
+	var myD MyStringer
+	myD, ok = tt.(MyStringer)
+	if !ok {
+		fmt.Println("time.Nanosecond does not implement MyStringer")
+	} else {
+		fmt.Println("time.Nanosecond implements MyStringer")
+		usesStringer(myD)
+	}
+	fmt.Println(tt.(MyStringer).String())
+	cType := reflect.TypeOf((*MyStringer)(nil)).Elem()
+	dType := reflect.TypeOf(time.Nanosecond)
+	fmt.Println(dType.Implements(cType))
+
+	if _, ok := tt.(MyStringer); !ok {
+		fmt.Println("time.Nanosecond does not implement MyStringer")
+	} else {
+		fmt.Println("time.Nanosecond implements MyStringer")
+	}
+
+	tt = 42
+	bar, ok := tt.(MyStringer)
+	if !ok {
+		fmt.Println("42 does not implement MyStringer")
+	} else {
+		fmt.Println("42 implements MyStringer")
+	}
+	_ = bar
+
+	if _, ok := tt.(MyStringer); !ok {
+		fmt.Println("42 does not implement MyStringer")
+	} else {
+		fmt.Println("42 implements MyStringer")
+	}
+}
+
+// Output:
+// TestStruct implements MyWriter
+// 11
+// 11
+// true
+// TestStruct implements MyWriter
+// 42 does not implement MyWriter
+// 42 does not implement MyWriter
+// time.Nanosecond implements MyStringer
+// 1ns
+// 1ns
+// true
+// time.Nanosecond implements MyStringer
+// 42 does not implement MyStringer
+// 42 does not implement MyStringer

_test/assert1.go

@@ -0,0 +1,85 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"time"
+)
+
+type TestStruct struct{}
+
+func (t TestStruct) String() string {
+	return "hello world"
+}
+
+func main() {
+	aType := reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
+
+	var t interface{}
+	t = time.Nanosecond
+	s, ok := t.(fmt.Stringer)
+	if !ok {
+		fmt.Println("time.Nanosecond does not implement fmt.Stringer")
+		return
+	}
+	fmt.Println(s.String())
+	fmt.Println(t.(fmt.Stringer).String())
+	bType := reflect.TypeOf(time.Nanosecond)
+	fmt.Println(bType.Implements(aType))
+
+	// not redundant with the above, because it goes through a slightly different code path.
+	if _, ok := t.(fmt.Stringer); !ok {
+		fmt.Println("time.Nanosecond does not implement fmt.Stringer")
+		return
+	} else {
+		fmt.Println("time.Nanosecond implements fmt.Stringer")
+	}
+
+	t = 42
+	foo, ok := t.(fmt.Stringer)
+	if !ok {
+		fmt.Println("42 does not implement fmt.Stringer")
+	} else {
+		fmt.Println("42 implements fmt.Stringer")
+		return
+	}
+	_ = foo
+
+	if _, ok := t.(fmt.Stringer); !ok {
+		fmt.Println("42 does not implement fmt.Stringer")
+	} else {
+		fmt.Println("42 implements fmt.Stringer")
+		return
+	}
+
+	var tt interface{}
+	tt = TestStruct{}
+	ss, ok := tt.(fmt.Stringer)
+	if !ok {
+		fmt.Println("TestStuct does not implement fmt.Stringer")
+		return
+	}
+	fmt.Println(ss.String())
+	fmt.Println(tt.(fmt.Stringer).String())
+	// TODO(mpl): uncomment when fixed
+	// cType := reflect.TypeOf(TestStruct{})
+	// fmt.Println(cType.Implements(aType))
+
+	if _, ok := tt.(fmt.Stringer); !ok {
+		fmt.Println("TestStuct does not implement fmt.Stringer")
+		return
+	} else {
+		fmt.Println("TestStuct implements fmt.Stringer")
+	}
+}
+
+// Output:
+// 1ns
+// 1ns
+// true
+// time.Nanosecond implements fmt.Stringer
+// 42 does not implement fmt.Stringer
+// 42 does not implement fmt.Stringer
+// hello world
+// hello world
+// TestStuct implements fmt.Stringer

_test/assign16.go

@@ -0,0 +1,15 @@
+package main
+
+type H struct {
+	bits uint
+}
+
+func main() {
+	h := &H{8}
+	var x uint = (1 << h.bits) >> 6
+
+	println(x)
+}
+
+// Output:
+// 4

_test/binstruct_ptr_map0.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+	"image"
+)
+
+func main() {
+	v := map[string]*image.Point{
+		"foo": {X: 3, Y: 2},
+		"bar": {X: 4, Y: 5},
+	}
+	fmt.Println(v["foo"], v["bar"])
+}
+
+// Output:
+// (3,2) (4,5)

_test/binstruct_ptr_slice0.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+	"image"
+)
+
+func main() {
+	v := []*image.Point{
+		{X: 3, Y: 2},
+		{X: 4, Y: 5},
+	}
+	fmt.Println(v)
+}
+
+// Output:
+// [(3,2) (4,5)]

_test/binstruct_slice0.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"fmt"
+	"image"
+)
+
+func main() {
+	v := []image.Point{
+		{X: 3, Y: 2},
+	}
+	fmt.Println(v)
+}
+
+// Output:
+// [(3,2)]

_test/composite14.go

@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+type T struct {
+	b []byte
+}
+
+func main() {
+	t := T{nil}
+	fmt.Println(t)
+}
+
+// Output:
+// {[]}

_test/composite15.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"fmt"
+)
+
+func interfaceAsInts() {
+	var a interface{}
+	b := 2
+	c := 3
+	a = []int{b, c}
+
+	d, ok := a.([]int)
+	if !ok {
+		println("nope")
+		return
+	}
+
+	for _, v := range d {
+		fmt.Println(v)
+	}
+}
+
+func interfaceAsInterfaces() {
+	var a, b, c interface{}
+	b = 2
+	c = 3
+	a = []interface{}{b, c}
+
+	d, ok := a.([]interface{})
+	if !ok {
+		println("nope")
+		return
+	}
+
+	for _, v := range d {
+		fmt.Println(v)
+	}
+}
+
+func main() {
+	interfaceAsInts()
+	interfaceAsInterfaces()
+}
+
+// Output:
+// 2
+// 3
+// 2
+// 3

_test/composite16.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"fmt"
+	"net/url"
+)
+
+func main() {
+	body := url.Values{
+		"Action": {"none"},
+	}
+	fmt.Println(body)
+}
+
+// Output:
+// map[Action:[none]]

_test/const17.go

@@ -0,0 +1,14 @@
+package main
+
+import "fmt"
+
+var t [7/3]int
+
+func main() {
+	t[0] = 3/2
+	t[1] = 5/2
+	fmt.Println(t)
+}
+
+// Output:
+// [1 2]

_test/const18.go

@@ -0,0 +1,11 @@
+package main
+
+import "time"
+
+func main() {
+	a := int64(time.Second)
+	println(a)
+}
+
+// Output:
+// 1000000000

_test/const19.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func get10Hours() time.Duration {
+	return 10 * time.Hour
+}
+
+func main() {
+	fmt.Println(get10Hours().String())
+}
+
+// Output:
+// 10h0m0s

_test/const20.go

@@ -0,0 +1,12 @@
+package main
+
+import "fmt"
+
+const maxLen = int64(int(^uint(0) >> 1))
+
+func main() {
+	fmt.Println(maxLen)
+}
+
+// Output:
+// 9223372036854775807

_test/const21.go

@@ -0,0 +1,12 @@
+package main
+
+const a = 64
+
+var b uint = a * a / 2
+
+func main() {
+	println(b)
+}
+
+// Output:
+// 2048

_test/convert0.go

@@ -0,0 +1,21 @@
+package main
+
+type T struct {
+	v int
+}
+
+type comparator func(T, T) bool
+
+func sort(items []T, comp comparator) {
+	println("in sort")
+}
+
+func compT(t0, t1 T) bool { return t0.v < t1.v }
+
+func main() {
+	a := []T{}
+	sort(a, comparator(compT))
+}
+
+// Output:
+// in sort

_test/convert1.go

@@ -0,0 +1,17 @@
+package main
+
+import "strconv"
+
+type atoidef func(s string) (int, error)
+
+func main() {
+	stdatoi := atoidef(strconv.Atoi)
+	n, err := stdatoi("7")
+	if err != nil {
+		panic(err)
+	}
+	println(n)
+}
+
+// Output:
+// 7

_test/convert2.go

@@ -0,0 +1,19 @@
+package main
+
+import "bufio"
+
+func fakeSplitFunc(data []byte, atEOF bool) (advance int, token []byte, err error) {
+	return 7, nil, nil
+}
+
+func main() {
+	splitfunc := bufio.SplitFunc(fakeSplitFunc)
+	n, _, err := splitfunc(nil, true)
+	if err != nil {
+		panic(err)
+	}
+	println(n)
+}
+
+// Output:
+// 7

_test/for15.go

@@ -0,0 +1,16 @@
+package main
+
+func f() int { println("in f"); return 1 }
+
+func main() {
+	for i := f(); ; {
+		println("in loop")
+		if i > 0 {
+			break
+		}
+	}
+}
+
+// Output:
+// in f
+// in loop

_test/for16.go

@@ -0,0 +1,16 @@
+package main
+
+func main() {
+	max := 1
+	for ; ; max-- {
+		if max == 0 {
+			break
+		}
+		println("in for")
+	}
+	println("bye")
+}
+
+// Output:
+// in for
+// bye

_test/fun23.go

@@ -0,0 +1,10 @@
+package main
+
+func f(x int) { return x }
+
+func main() {
+	print("hello")
+}
+
+// Error:
+// 3:17: too many arguments to return

_test/fun24.go

@@ -0,0 +1,10 @@
+package main
+
+func f(x int) (int, int) { return x, "foo" }
+
+func main() {
+	print("hello")
+}
+
+// Error:
+// cannot use "foo" (type stringT) as type intT in return argument

_test/fun25.go

@@ -0,0 +1,10 @@
+package main
+
+func f(x string) (a int, b int) { return x, 5 }
+
+func main() {
+	print("hello")
+}
+
+// Error:
+// cannot use x (type stringT) as type intT in return argument

_test/fun26.go

@@ -0,0 +1,17 @@
+package main
+
+type F func() (int, error)
+
+func f1() (int, error) { return 3, nil }
+
+func f2(a string, f F) {
+	c, _ := f()
+	println(a, c)
+}
+
+func main() {
+	f2("hello", F(f1))
+}
+
+// Output:
+// hello 3

_test/goto1.go

@@ -0,0 +1,12 @@
+package main
+
+func main() {
+	if true {
+		goto here
+	}
+here:
+	println("ok")
+}
+
+// Output:
+// ok

_test/interface47.go

@@ -0,0 +1,32 @@
+package main
+
+type Doer interface {
+	Do() error
+}
+
+type T struct {
+	Name string
+}
+
+func (t *T) Do() error { println("in do"); return nil }
+
+func f() (Doer, error) { return &T{"truc"}, nil }
+
+type Ev struct {
+	doer func() (Doer, error)
+}
+
+func (e *Ev) do() {
+	d, _ := e.doer()
+	d.Do()
+}
+
+func main() {
+	e := &Ev{f}
+	println(e != nil)
+	e.do()
+}
+
+// Output:
+// true
+// in do

_test/issue-880.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+)
+
+func main() {
+	var buf1 = make([]byte, 1024)
+	var buf2 []byte
+	buf1 = []byte("Hallo\nTest\nLine3")
+
+	s := bufio.NewScanner(bytes.NewReader(buf1))
+	for s.Scan() {
+		buf2 = append(buf2, append(s.Bytes(), []byte("\n")...)...)
+	}
+	print(string(buf2))
+}
+
+// Output:
+// Hallo
+// Test
+// Line3

_test/issue-993.go

@@ -0,0 +1,15 @@
+package main
+
+var m map[string]int64
+
+func initVar() {
+	m = make(map[string]int64)
+}
+
+func main() {
+	initVar()
+	println(len(m))
+}
+
+// Output:
+// 0

_test/nil3.go

@@ -0,0 +1,28 @@
+package main
+
+type I interface {
+	Hello()
+}
+
+type T struct {
+	h I
+}
+
+func (t *T) Hello() { println("Hello") }
+
+func main() {
+	t := &T{}
+	println(t.h != nil)
+	println(t.h == nil)
+	t.h = t
+	println(t.h != nil)
+	println(t.h == nil)
+	t.h.Hello()
+}
+
+// Output:
+// false
+// true
+// true
+// false
+// Hello

_test/select1.go

@@ -1,18 +1,20 @@
 package main
 
-import "time"
-import "fmt"
+import (
+	"fmt"
+	"time"
+)
 
 func main() {
 	c1 := make(chan string)
 	c2 := make(chan string)
 
 	go func() {
-		time.Sleep(1e9)
+		time.Sleep(1e7)
 		c1 <- "one"
 	}()
 	go func() {
-		time.Sleep(2e9)
+		time.Sleep(2e7)
 		c2 <- "two"
 	}()
 

_test/select14.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+const (
+	period    = 100 * time.Millisecond
+	precision = 5 * time.Millisecond
+)
+
+func main() {
+	counter := 0
+	p := time.Now()
+	ticker := time.NewTicker(period)
+	ch := make(chan int)
+
+	go func() {
+		for i := 0; i < 3; i++ {
+			select {
+			case t := <-ticker.C:
+				counter = counter + 1
+				ch <- counter
+				if d := t.Sub(p) - period; d < -precision || d > precision {
+					fmt.Println("wrong delay", d)
+				}
+				p = t
+			}
+		}
+		ch <- 0
+	}()
+	for c := range ch {
+		if c == 0 {
+			break
+		}
+		println(c)
+	}
+}
+
+// Output:
+// 1
+// 2
+// 3

_test/select15.go

@@ -0,0 +1,23 @@
+package main
+
+type T struct {
+	c1 chan string
+	c2 chan string
+}
+
+func main() {
+	t := &T{}
+	t.c2 = make(chan string)
+
+	go func(c chan string) { c <- "done" }(t.c2)
+
+	select {
+	case msg := <-t.c1:
+		println("received from c1:", msg)
+	case <-t.c2:
+	}
+	println("Bye")
+}
+
+// Output:
+// Bye

_test/slice.go

@@ -0,0 +1,11 @@
+package main
+
+import "fmt"
+
+func main() {
+    a := [2][2]int{{0, 1}, {2, 3}}
+    fmt.Println(a[0][0:])
+}
+
+// Output:
+// [0 1]

_test/time14.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+var t time.Time
+
+func f() time.Time {
+	time := t
+	return time
+}
+
+func main() {
+	fmt.Println(f())
+}
+
+// Output:
+// 0001-01-01 00:00:00 +0000 UTC

_test/time15.go

@@ -0,0 +1,15 @@
+package main
+
+import "time"
+
+type TimeValue time.Time
+
+func (v *TimeValue) decode() { println("in decode") }
+
+func main() {
+	var tv TimeValue
+	tv.decode()
+}
+
+// Output:
+// in decode

_test/var15.go

@@ -0,0 +1,15 @@
+package main
+
+var a int = 2
+
+func inca() {
+	a = a + 1
+}
+
+func main() {
+	inca()
+	println(a)
+}
+
+// Output:
+// 3

cmd/yaegi/extract.go

@@ -10,7 +10,7 @@ import (
 	"path"
 	"strings"
 
-	"github.com/traefik/yaegi/internal/extract"
+	"github.com/traefik/yaegi/extract"
 )
 
 func extractCmd(arg []string) error {

cmd/yaegi/help.go

@@ -14,6 +14,7 @@ The commands are:
     help        print usage information
     run         execute a Go program from source
     test        execute test functions in a Go package
+    version     print version
 
 Use "yaegi help <command>" for more information about a command.
 
@@ -37,6 +38,9 @@ func help(arg []string) error {
 		return run([]string{"-h"})
 	case Test:
 		return test([]string{"-h"})
+	case Version:
+		fmt.Println("Usage: yaegi version")
+		return nil
 	default:
 		return fmt.Errorf("help: invalid yaegi command: %v", cmd)
 	}

cmd/yaegi/run.go

@@ -6,6 +6,7 @@ import (
 	"go/build"
 	"io/ioutil"
 	"os"
+	"strconv"
 	"strings"
 
 	"github.com/traefik/yaegi/interp"
@@ -17,19 +18,21 @@ import (
 
 func run(arg []string) error {
 	var interactive bool
-	var useSyscall bool
-	var useUnrestricted bool
-	var useUnsafe bool
 	var tags string
 	var cmd string
 	var err error
 
+	// The following flags are initialized from environment.
+	useSyscall, _ := strconv.ParseBool(os.Getenv("YAEGI_SYSCALL"))
+	useUnrestricted, _ := strconv.ParseBool(os.Getenv("YAEGI_UNRESTRICTED"))
+	useUnsafe, _ := strconv.ParseBool(os.Getenv("YAEGI_UNSAFE"))
+
 	rflag := flag.NewFlagSet("run", flag.ContinueOnError)
 	rflag.BoolVar(&interactive, "i", false, "start an interactive REPL")
-	rflag.BoolVar(&useSyscall, "syscall", false, "include syscall symbols")
-	rflag.BoolVar(&useUnrestricted, "unrestricted", false, "include unrestricted symbols")
+	rflag.BoolVar(&useSyscall, "syscall", useSyscall, "include syscall symbols")
+	rflag.BoolVar(&useUnrestricted, "unrestricted", useUnrestricted, "include unrestricted symbols")
 	rflag.StringVar(&tags, "tags", "", "set a list of build tags")
-	rflag.BoolVar(&useUnsafe, "unsafe", false, "include usafe symbols")
+	rflag.BoolVar(&useUnsafe, "unsafe", useUnsafe, "include unsafe symbols")
 	rflag.StringVar(&cmd, "e", "", "set the command to be executed (instead of script or/and shell)")
 	rflag.Usage = func() {
 		fmt.Println("Usage: yaegi run [options] [path] [args]")
@@ -46,24 +49,33 @@ func run(arg []string) error {
 	i.Use(interp.Symbols)
 	if useSyscall {
 		i.Use(syscall.Symbols)
+		// Using a environment var allows a nested interpreter to import the syscall package.
+		if err := os.Setenv("YAEGI_SYSCALL", "1"); err != nil {
+			return err
+		}
 	}
 	if useUnsafe {
 		i.Use(unsafe.Symbols)
+		if err := os.Setenv("YAEGI_UNSAFE", "1"); err != nil {
+			return err
+		}
 	}
 	if useUnrestricted {
 		// Use of unrestricted symbols should always follow stdlib and syscall symbols, to update them.
 		i.Use(unrestricted.Symbols)
+		if err := os.Setenv("YAEGI_UNRESTRICTED", "1"); err != nil {
+			return err
+		}
 	}
 
 	if cmd != "" {
 		_, err = i.Eval(cmd)
-		showError(err)
 	}
 
 	if len(args) == 0 {
 		if interactive || cmd == "" {
-			_, err = i.REPL()
 			showError(err)
+			_, err = i.REPL()
 		}
 		return err
 	}
@@ -78,7 +90,6 @@ func run(arg []string) error {
 	} else {
 		_, err = i.EvalPath(path)
 	}
-	showError(err)
 
 	if err != nil {
 		return err
@@ -86,7 +97,6 @@ func run(arg []string) error {
 
 	if interactive {
 		_, err = i.REPL()
-		showError(err)
 	}
 	return err
 }

cmd/yaegi/test.go

@@ -1,11 +1,14 @@
 package main
 
 import (
+	"errors"
 	"flag"
 	"fmt"
 	"go/build"
 	"os"
+	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -18,22 +21,24 @@ import (
 
 func test(arg []string) (err error) {
 	var (
-		bench           string
-		benchmem        bool
-		benchtime       string
-		count           string
-		cpu             string
-		failfast        bool
-		run             string
-		short           bool
-		tags            string
-		useUnrestricted bool
-		useUnsafe       bool
-		useSyscall      bool
-		timeout         string
-		verbose         bool
+		bench     string
+		benchmem  bool
+		benchtime string
+		count     string
+		cpu       string
+		failfast  bool
+		run       string
+		short     bool
+		tags      string
+		timeout   string
+		verbose   bool
 	)
 
+	// The following flags are initialized from environment.
+	useSyscall, _ := strconv.ParseBool(os.Getenv("YAEGI_SYSCALL"))
+	useUnrestricted, _ := strconv.ParseBool(os.Getenv("YAEGI_UNRESTRICTED"))
+	useUnsafe, _ := strconv.ParseBool(os.Getenv("YAEGI_UNSAFE"))
+
 	tflag := flag.NewFlagSet("test", flag.ContinueOnError)
 	tflag.StringVar(&bench, "bench", "", "Run only those benchmarks matching a regular expression.")
 	tflag.BoolVar(&benchmem, "benchmem", false, "Print memory allocation statistics for benchmarks.")
@@ -45,9 +50,9 @@ func test(arg []string) (err error) {
 	tflag.BoolVar(&short, "short", false, "Tell long-running tests to shorten their run time.")
 	tflag.StringVar(&tags, "tags", "", "Set a list of build tags.")
 	tflag.StringVar(&timeout, "timeout", "", "If a test binary runs longer than duration d, panic.")
-	tflag.BoolVar(&useUnrestricted, "unrestricted", false, "Include unrestricted symbols.")
-	tflag.BoolVar(&useUnsafe, "unsafe", false, "Include usafe symbols.")
-	tflag.BoolVar(&useSyscall, "syscall", false, "Include syscall symbols.")
+	tflag.BoolVar(&useUnrestricted, "unrestricted", useUnrestricted, "Include unrestricted symbols.")
+	tflag.BoolVar(&useUnsafe, "unsafe", useUnsafe, "Include usafe symbols.")
+	tflag.BoolVar(&useSyscall, "syscall", useSyscall, "Include syscall symbols.")
 	tflag.BoolVar(&verbose, "v", false, "Verbose output: log all tests as they are run.")
 	tflag.Usage = func() {
 		fmt.Println("Usage: yaegi test [options] [path]")
@@ -98,18 +103,40 @@ func test(arg []string) (err error) {
 	testing.Init()
 	os.Args = tf
 	flag.Parse()
+	path += string(filepath.Separator)
+	var dir string
+
+	switch strings.Split(path, string(filepath.Separator))[0] {
+	case ".", "..", string(filepath.Separator):
+		dir = path
+	default:
+		dir = filepath.Join(build.Default.GOPATH, "src", path)
+	}
+	if err = os.Chdir(dir); err != nil {
+		return err
+	}
 
 	i := interp.New(interp.Options{GoPath: build.Default.GOPATH, BuildTags: strings.Split(tags, ",")})
 	i.Use(stdlib.Symbols)
 	i.Use(interp.Symbols)
 	if useSyscall {
 		i.Use(syscall.Symbols)
+		// Using a environment var allows a nested interpreter to import the syscall package.
+		if err := os.Setenv("YAEGI_SYSCALL", "1"); err != nil {
+			return err
+		}
 	}
 	if useUnrestricted {
 		i.Use(unrestricted.Symbols)
+		if err := os.Setenv("YAEGI_UNRESTRICTED", "1"); err != nil {
+			return err
+		}
 	}
 	if useUnsafe {
 		i.Use(unsafe.Symbols)
+		if err := os.Setenv("YAEGI_UNSAFE", "1"); err != nil {
+			return err
+		}
 	}
 	if err = i.EvalTest(path); err != nil {
 		return err
@@ -117,7 +144,11 @@ func test(arg []string) (err error) {
 
 	benchmarks := []testing.InternalBenchmark{}
 	tests := []testing.InternalTest{}
-	for name, sym := range i.Symbols(path) {
+	syms, ok := i.Symbols(path)[path]
+	if !ok {
+		return errors.New("No tests found")
+	}
+	for name, sym := range syms {
 		switch fun := sym.Interface().(type) {
 		case func(*testing.B):
 			benchmarks = append(benchmarks, testing.InternalBenchmark{name, fun})

cmd/yaegi/yaegi.go

@@ -71,7 +71,16 @@ Options:
 	-unsafe
 	  include unsafe symbols.
 
-Debugging support (may be removed at any time):
+Environment variables:
+  YAEGI_SYSCALL=1
+    Include syscall symbols (same as -syscall flag).
+  YAEGI_UNRESTRICTED=1
+    Include unrestricted symbols (same as -unrestricted flag).
+  YAEGI_UNSAFE=1
+    Include unsafe symbols (same as -unsafe flag).
+  YAEGI_PROMPT=1
+    Force enable the printing of the REPL prompt and the result of last instruction,
+    even if stdin is not a terminal.
   YAEGI_AST_DOT=1
     Generate and display graphviz dot of AST with dotty(1)
   YAEGI_CFG_DOT=1
@@ -90,6 +99,8 @@ import (
 	"fmt"
 	"log"
 	"os"
+
+	"github.com/traefik/yaegi/interp"
 )
 
 const (
@@ -97,8 +108,11 @@ const (
 	Help    = "help"
 	Run     = "run"
 	Test    = "test"
+	Version = "version"
 )
 
+var version = "devel" // This may be overwritten at build time.
+
 func main() {
 	var cmd string
 	var err error
@@ -119,6 +133,8 @@ func main() {
 		err = run(os.Args[2:])
 	case Test:
 		err = test(os.Args[2:])
+	case Version:
+		fmt.Println(version)
 	default:
 		// If no command is given, fallback to default "run" command.
 		// This allows scripts starting with "#!/usr/bin/env yaegi",
@@ -129,8 +145,10 @@ func main() {
 	}
 
 	if err != nil && !errors.Is(err, flag.ErrHelp) {
-		err = fmt.Errorf("%s: %w", cmd, err)
-		fmt.Fprintln(os.Stderr, err)
+		fmt.Fprintln(os.Stderr, fmt.Errorf("%s: %w", cmd, err))
+		if p, ok := err.(interp.Panic); ok {
+			fmt.Fprintln(os.Stderr, string(p.Stack))
+		}
 		exitCode = 1
 	}
 	os.Exit(exitCode)

example/pkg/_pkg13/src/guthib.com/foo/bar/main.go

@@ -0,0 +1,13 @@
+package main
+
+import (
+	"fmt"
+
+	"guthib.com/bat/baz"
+)
+
+func main() {
+	t := baz.NewT()
+
+	fmt.Printf("%s", t.A3)
+}

example/pkg/_pkg13/src/guthib.com/foo/bar/vendor/guthib.com/bat/baz/baz.go

@@ -0,0 +1,22 @@
+package baz
+
+func NewT() *T {
+	return &T{
+		A1: make([]U, 0),
+		A3: "foobar",
+	}
+}
+
+type T struct {
+	A1 []U
+	A3 string
+}
+
+type U struct {
+	B1 V
+	B2 V
+}
+
+type V struct {
+	C1 string
+}

example/pkg/pkg_test.go

@@ -93,6 +93,12 @@ func TestPackages(t *testing.T) {
 			expected: "Yo hello",
 			evalFile: "./_pkg12/src/guthib.com/foo/main.go",
 		},
+		{
+			desc:     "eval main with vendor",
+			goPath:   "./_pkg13/",
+			expected: "foobar",
+			evalFile: "./_pkg13/src/guthib.com/foo/bar/main.go",
+		},
 	}
 
 	for _, test := range testCases {

extract/extract.go

@@ -436,10 +436,12 @@ func GetMinor(part string) string {
 	return minor
 }
 
+const defaultMinorVersion = 15
+
 func genBuildTags() (string, error) {
 	version := runtime.Version()
-	if version == "devel" {
-		return "", nil
+	if strings.HasPrefix(version, "devel") {
+		return "", fmt.Errorf("extracting only supported with stable releases of Go, not %v", version)
 	}
 	parts := strings.Split(version, ".")
 
@@ -452,6 +454,11 @@ func genBuildTags() (string, error) {
 		return "", fmt.Errorf("failed to parse version: %v", err)
 	}
 
+	// Only append an upper bound if we are not on the latest go
+	if minor >= defaultMinorVersion {
+		return currentGoVersion, nil
+	}
+
 	nextGoVersion := parts[0] + "." + strconv.Itoa(minor+1)
 
 	return currentGoVersion + ",!" + nextGoVersion, nil

generate.go

@@ -1,6 +1,6 @@
 package yaegi
 
-//go:generate go generate github.com/traefik/yaegi/internal/extract
+//go:generate go generate github.com/traefik/yaegi/internal/cmd/extract
 //go:generate go generate github.com/traefik/yaegi/interp
 //go:generate go generate github.com/traefik/yaegi/stdlib
 //go:generate go generate github.com/traefik/yaegi/stdlib/syscall

internal/cmd/extract/extract.go

@@ -28,7 +28,7 @@ import (
 	"runtime"
 	"strings"
 
-	"github.com/traefik/yaegi/internal/extract"
+	"github.com/traefik/yaegi/extract"
 )
 
 var (
@@ -84,11 +84,12 @@ func main() {
 			oFile = strings.ReplaceAll(importPath, "/", "_") + ".go"
 		}
 
-		prefix := runtime.Version()
-		if runtime.Version() != "devel" {
-			parts := strings.Split(runtime.Version(), ".")
-			prefix = parts[0] + "_" + extract.GetMinor(parts[1])
+		version := runtime.Version()
+		if strings.HasPrefix(version, "devel") {
+			log.Fatalf("extracting only supported with stable releases of Go, not %v", version)
 		}
+		parts := strings.Split(version, ".")
+		prefix := parts[0] + "_" + extract.GetMinor(parts[1])
 
 		f, err := os.Create(prefix + "_" + oFile)
 		if err != nil {

internal/cmd/genop/genop.go

@@ -196,6 +196,18 @@ func {{$name}}Const(n *node) {
 		{{- if $op.Shift}}
 		v := constant.Shift(vConstantValue(v0), token.{{tokenFromName $name}}, uint(vUint(v1)))
 		n.rval.Set(reflect.ValueOf(v))
+		{{- else if (eq $op.Name "/")}}
+		var operator token.Token
+		// When the result of the operation is expected to be an int (because both
+		// operands are ints), we want to force the type of the whole expression to be an
+		// int (and not a float), which is achieved by using the QUO_ASSIGN operator.
+		if n.typ.untyped && isInt(n.typ.rtype) {
+			operator = token.QUO_ASSIGN
+		} else {
+			operator = token.QUO
+		}
+		v := constant.BinaryOp(vConstantValue(v0), operator, vConstantValue(v1))
+		n.rval.Set(reflect.ValueOf(v))
 		{{- else}}
 		v := constant.BinaryOp(vConstantValue(v0), token.{{tokenFromName $name}}, vConstantValue(v1))
 		n.rval.Set(reflect.ValueOf(v))
@@ -395,10 +407,10 @@ func {{$name}}Const(n *node) {
 	case isConst:
 		v := constant.UnaryOp(token.{{tokenFromName $name}}, vConstantValue(v0), 0)
 		n.rval.Set(reflect.ValueOf(v))
-	case isInt(t):
-		n.rval.SetInt({{$op.Name}} v0.Int())
 	case isUint(t):
 		n.rval.SetUint({{$op.Name}} v0.Uint())
+	case isInt(t):
+		n.rval.SetInt({{$op.Name}} v0.Int())
 	{{- if $op.Float}}
 	case isFloat(t):
 		n.rval.SetFloat({{$op.Name}} v0.Float())

interp/ast.go

@@ -51,12 +51,14 @@ const (
 	fieldList
 	fileStmt
 	forStmt0     // for {}
-	forStmt1     // for cond {}
-	forStmt2     // for init; cond; {}
-	forStmt3     // for ; cond; post {}
-	forStmt3a    // for init; ; post {}
-	forStmt4     // for init; cond; post {}
-	forRangeStmt // for range
+	forStmt1     // for init; ; {}
+	forStmt2     // for cond {}
+	forStmt3     // for init; cond; {}
+	forStmt4     // for ; ; post {}
+	forStmt5     // for ; cond; post {}
+	forStmt6     // for init; ; post {}
+	forStmt7     // for init; cond; post {}
+	forRangeStmt // for range {}
 	funcDecl
 	funcLit
 	funcType
@@ -134,8 +136,10 @@ var kinds = [...]string{
 	forStmt1:          "forStmt1",
 	forStmt2:          "forStmt2",
 	forStmt3:          "forStmt3",
-	forStmt3a:         "forStmt3a",
 	forStmt4:          "forStmt4",
+	forStmt5:          "forStmt5",
+	forStmt6:          "forStmt6",
+	forStmt7:          "forStmt7",
 	forRangeStmt:      "forRangeStmt",
 	funcDecl:          "funcDecl",
 	funcType:          "funcType",
@@ -654,23 +658,23 @@ func (interp *Interpreter) ast(src, name string, inc bool) (string, *node, error
 		case *ast.ForStmt:
 			// Disambiguate variants of FOR statements with a node kind per variant
 			var kind nkind
-			if a.Cond == nil {
-				if a.Init != nil && a.Post != nil {
-					kind = forStmt3a
-				} else {
-					kind = forStmt0
-				}
-			} else {
-				switch {
-				case a.Init == nil && a.Post == nil:
-					kind = forStmt1
-				case a.Init != nil && a.Post == nil:
-					kind = forStmt2
-				case a.Init == nil && a.Post != nil:
-					kind = forStmt3
-				default:
-					kind = forStmt4
-				}
+			switch {
+			case a.Cond == nil && a.Init == nil && a.Post == nil:
+				kind = forStmt0
+			case a.Cond == nil && a.Init != nil && a.Post == nil:
+				kind = forStmt1
+			case a.Cond != nil && a.Init == nil && a.Post == nil:
+				kind = forStmt2
+			case a.Cond != nil && a.Init != nil && a.Post == nil:
+				kind = forStmt3
+			case a.Cond == nil && a.Init == nil && a.Post != nil:
+				kind = forStmt4
+			case a.Cond != nil && a.Init == nil && a.Post != nil:
+				kind = forStmt5
+			case a.Cond == nil && a.Init != nil && a.Post != nil:
+				kind = forStmt6
+			case a.Cond != nil && a.Init != nil && a.Post != nil:
+				kind = forStmt7
 			}
 			st.push(addChild(&root, anc, pos, kind, aNop), nod)
 

interp/cfg.go

@@ -66,6 +66,44 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			return false
 		}
 		switch n.kind {
+		case binaryExpr, unaryExpr, parenExpr:
+			if isBoolAction(n) {
+				break
+			}
+			// Gather assigned type if set, to give context for type propagation at post-order.
+			switch n.anc.kind {
+			case assignStmt, defineStmt:
+				a := n.anc
+				i := childPos(n) - a.nright
+				if i < 0 {
+					break
+				}
+				if len(a.child) > a.nright+a.nleft {
+					i--
+				}
+				dest := a.child[i]
+				if dest.typ != nil && !isInterface(dest.typ) {
+					// Interface type are not propagated, and will be resolved at post-order.
+					n.typ = dest.typ
+				}
+			case binaryExpr, unaryExpr, parenExpr:
+				n.typ = n.anc.typ
+			}
+
+		case defineStmt:
+			// Determine type of variables initialized at declaration, so it can be propagated.
+			if n.nleft+n.nright == len(n.child) {
+				// No type was specified on the left hand side, it will resolved at post-order.
+				break
+			}
+			n.typ, err = nodeType(interp, sc, n.child[n.nleft])
+			if err != nil {
+				break
+			}
+			for i := 0; i < n.nleft; i++ {
+				n.child[i].typ = n.typ
+			}
+
 		case blockStmt:
 			if n.anc != nil && n.anc.kind == rangeStmt {
 				// For range block: ensure that array or map type is propagated to iterators
@@ -159,7 +197,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 
 		case breakStmt, continueStmt, gotoStmt:
 			if len(n.child) > 0 {
-				// Handle labeled statements
+				// Handle labeled statements.
 				label := n.child[0].ident
 				if sym, _, ok := sc.lookup(label); ok {
 					if sym.kind != labelSym {
@@ -176,25 +214,23 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 
 		case labeledStmt:
 			label := n.child[0].ident
-			if sym, _, ok := sc.lookup(label); ok {
-				if sym.kind != labelSym {
-					err = n.child[0].cfgErrorf("label %s not defined", label)
-					break
-				}
+			// TODO(marc): labels must be stored outside of symbols to avoid collisions
+			// Used labels are searched in current and sub scopes, not upper ones.
+			if sym, ok := sc.lookdown(label); ok {
 				sym.node = n
 				n.sym = sym
 			} else {
 				n.sym = &symbol{kind: labelSym, node: n, index: -1}
-				sc.sym[label] = n.sym
 			}
+			sc.sym[label] = n.sym
 
 		case caseClause:
 			sc = sc.pushBloc()
 			if sn := n.anc.anc; sn.kind == typeSwitch && sn.child[1].action == aAssign {
-				// Type switch clause with a var defined in switch guard
+				// Type switch clause with a var defined in switch guard.
 				var typ *itype
 				if len(n.child) == 2 {
-					// 1 type in clause: define the var with this type in the case clause scope
+					// 1 type in clause: define the var with this type in the case clause scope.
 					switch {
 					case n.child[0].ident == nilIdent:
 						typ = sc.getType("interface{}")
@@ -204,7 +240,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 						typ, err = nodeType(interp, sc, n.child[0])
 					}
 				} else {
-					// define the var with the type in the switch guard expression
+					// Define the var with the type in the switch guard expression.
 					typ = sn.child[1].child[1].child[0].typ
 				}
 				if err != nil {
@@ -252,8 +288,12 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				// Get type from ancestor (implicit type)
 				if n.anc.kind == keyValueExpr && n == n.anc.child[0] {
 					n.typ = n.anc.typ.key
-				} else if n.anc.typ != nil {
-					n.typ = n.anc.typ.val
+				} else if atyp := n.anc.typ; atyp != nil {
+					if atyp.cat == valueT {
+						n.typ = &itype{cat: valueT, rtype: atyp.rtype.Elem()}
+					} else {
+						n.typ = atyp.val
+					}
 				}
 				if n.typ == nil {
 					err = n.cfgErrorf("undefined type")
@@ -285,11 +325,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				}
 			}
 
-		case forStmt0, forRangeStmt:
-			sc = sc.pushBloc()
-			sc.loop, sc.loopRestart = n, n.child[0]
-
-		case forStmt1, forStmt2, forStmt3, forStmt3a, forStmt4:
+		case forStmt0, forStmt1, forStmt2, forStmt3, forStmt4, forStmt5, forStmt6, forStmt7, forRangeStmt:
 			sc = sc.pushBloc()
 			sc.loop, sc.loopRestart = n, n.lastChild()
 
@@ -386,9 +422,10 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				return false
 			}
 
-			if n.child[1].kind == identExpr {
+			switch n.child[1].kind {
+			case identExpr, selectorExpr:
 				n.typ = &itype{cat: aliasT, val: typ, name: typeName}
-			} else {
+			default:
 				n.typ = typ
 				n.typ.name = typeName
 			}
@@ -443,14 +480,11 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				n.gen = nop
 				break
 			}
-			if n.anc.kind == commClause {
-				n.gen = nop
-				break
-			}
+
 			var atyp *itype
 			if n.nleft+n.nright < len(n.child) {
 				if atyp, err = nodeType(interp, sc, n.child[n.nleft]); err != nil {
-					return
+					break
 				}
 			}
 
@@ -554,6 +588,14 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 					n.gen = nop
 					src.findex = dest.findex
 					src.level = level
+				case n.action == aAssign && len(n.child) < 4 && !src.rval.IsValid() && isArithmeticAction(src):
+					// Optimize single assignments from some arithmetic operations.
+					// Skip the assign operation entirely, the source frame index is set
+					// to destination index, avoiding extra memory alloc and duplication.
+					src.typ = dest.typ
+					src.findex = dest.findex
+					src.level = level
+					n.gen = nop
 				case src.kind == basicLit && !src.rval.IsValid():
 					// Assign to nil.
 					src.rval = reflect.New(dest.typ.TypeOf()).Elem()
@@ -569,7 +611,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				}
 				if n.anc.kind == constDecl {
 					n.gen = nop
-					n.findex = -1
+					n.findex = notInFrame
 					if sym, _, ok := sc.lookup(dest.ident); ok {
 						sym.kind = constSym
 					}
@@ -610,7 +652,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				if n.child[0].ident == "_" {
 					lc.gen = typeAssertStatus
 				} else {
-					lc.gen = typeAssert2
+					lc.gen = typeAssertLong
 				}
 				n.gen = nop
 			case unaryExpr:
@@ -639,7 +681,12 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			}
 
 			switch n.action {
-			case aRem, aShl, aShr:
+			case aRem:
+				n.typ = c0.typ
+			case aShl, aShr:
+				if c0.typ.untyped {
+					break
+				}
 				n.typ = c0.typ
 			case aEqual, aNotEqual:
 				n.typ = sc.getType("bool")
@@ -670,7 +717,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				// This operation involved constants, and the result is already computed
 				// by constOp and available in n.rval. Nothing else to do at execution.
 				n.gen = nop
-				n.findex = -1
+				n.findex = notInFrame
 			case n.anc.kind == assignStmt && n.anc.action == aAssign:
 				// To avoid a copy in frame, if the result is to be assigned, store it directly
 				// at the frame location of destination.
@@ -811,7 +858,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				}
 				switch {
 				case n.typ.cat == builtinT:
-					n.findex = -1
+					n.findex = notInFrame
 					n.val = nil
 				case n.anc.kind == returnStmt:
 					// Store result directly to frame output location, to avoid a frame copy.
@@ -853,9 +900,14 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 					n.rval = c1.rval
 				case c1.rval.IsValid() && isConstType(c0.typ):
 					n.gen = nop
-					n.findex = -1
+					n.findex = notInFrame
 					n.typ = c0.typ
-					n.rval = c1.rval
+					if c, ok := c1.rval.Interface().(constant.Value); ok {
+						i, _ := constant.Int64Val(constant.ToInt(c))
+						n.rval = reflect.ValueOf(i).Convert(c0.typ.rtype)
+					} else {
+						n.rval = c1.rval.Convert(c0.typ.rtype)
+					}
 				default:
 					n.gen = convert
 					n.typ = c0.typ
@@ -911,7 +963,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 						}
 					}
 				} else {
-					n.findex = -1
+					n.findex = notInFrame
 				}
 			}
 
@@ -982,7 +1034,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 
 			n.findex = sc.add(n.typ)
 			// TODO: Check that composite literal expr matches corresponding type
-			n.gen = compositeGenerator(n, n.typ)
+			n.gen = compositeGenerator(n, n.typ, nil)
 
 		case fallthroughtStmt:
 			if n.anc.kind != caseBody {
@@ -992,7 +1044,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 		case fileStmt:
 			wireChild(n, varDecl)
 			sc = sc.pop()
-			n.findex = -1
+			n.findex = notInFrame
 
 		case forStmt0: // for {}
 			body := n.child[0]
@@ -1000,7 +1052,14 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			body.tnext = n.start
 			sc = sc.pop()
 
-		case forStmt1: // for cond {}
+		case forStmt1: // for init; ; {}
+			init, body := n.child[0], n.child[1]
+			n.start = init.start
+			init.tnext = body.start
+			body.tnext = n.start
+			sc = sc.pop()
+
+		case forStmt2: // for cond {}
 			cond, body := n.child[0], n.child[1]
 			if !isBool(cond.typ) {
 				err = cond.cfgErrorf("non-bool used as for condition")
@@ -1019,7 +1078,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			setFNext(cond, n)
 			sc = sc.pop()
 
-		case forStmt2: // for init; cond; {}
+		case forStmt3: // for init; cond; {}
 			init, cond, body := n.child[0], n.child[1], n.child[2]
 			if !isBool(cond.typ) {
 				err = cond.cfgErrorf("non-bool used as for condition")
@@ -1041,7 +1100,14 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			setFNext(cond, n)
 			sc = sc.pop()
 
-		case forStmt3: // for ; cond; post {}
+		case forStmt4: // for ; ; post {}
+			post, body := n.child[0], n.child[1]
+			n.start = body.start
+			post.tnext = body.start
+			body.tnext = post.start
+			sc = sc.pop()
+
+		case forStmt5: // for ; cond; post {}
 			cond, post, body := n.child[0], n.child[1], n.child[2]
 			if !isBool(cond.typ) {
 				err = cond.cfgErrorf("non-bool used as for condition")
@@ -1061,7 +1127,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			body.tnext = post.start
 			sc = sc.pop()
 
-		case forStmt3a: // for init; ; post {}
+		case forStmt6: // for init; ; post {}
 			init, post, body := n.child[0], n.child[1], n.child[2]
 			n.start = init.start
 			init.tnext = body.start
@@ -1069,7 +1135,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			post.tnext = body.start
 			sc = sc.pop()
 
-		case forStmt4: // for init; cond; post {}
+		case forStmt7: // for init; cond; post {}
 			init, cond, post, body := n.child[0], n.child[1], n.child[2], n.child[3]
 			if !isBool(cond.typ) {
 				err = cond.cfgErrorf("non-bool used as for condition")
@@ -1129,7 +1195,6 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			sym, level, found := sc.lookup(n.ident)
 			if !found {
 				// retry with the filename, in case ident is a package name.
-				// TODO(mpl): maybe we improve lookup itself so it can deal with that.
 				sym, level, found = sc.lookup(filepath.Join(n.ident, baseName))
 				if !found {
 					err = n.cfgErrorf("undefined: %s", n.ident)
@@ -1302,7 +1367,12 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			}
 
 		case returnStmt:
-			if mustReturnValue(sc.def.child[2]) {
+			if len(n.child) > sc.def.typ.numOut() {
+				err = n.cfgErrorf("too many arguments to return")
+				break
+			}
+			returnSig := sc.def.child[2]
+			if mustReturnValue(returnSig) {
 				nret := len(n.child)
 				if nret == 1 && isCall(n.child[0]) {
 					nret = n.child[0].child[0].typ.numOut()
@@ -1316,13 +1386,19 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			n.tnext = nil
 			n.val = sc.def
 			for i, c := range n.child {
+				var typ *itype
+				typ, err = nodeType(interp, sc.upperLevel(), returnSig.child[1].fieldType(i))
+				if err != nil {
+					return
+				}
+				// TODO(mpl): move any of that code to typecheck?
+				c.typ.node = c
+				if !c.typ.assignableTo(typ) {
+					err = fmt.Errorf("cannot use %v (type %v) as type %v in return argument", c.ident, c.typ.cat, typ.cat)
+					return
+				}
 				if c.typ.cat == nilT {
 					// nil: Set node value to zero of return type
-					f := sc.def
-					var typ *itype
-					if typ, err = nodeType(interp, sc, f.child[2].child[1].fieldType(i)); err != nil {
-						return
-					}
 					if typ.cat == funcT {
 						// Wrap the typed nil value in a node, as per other interpreter functions
 						c.rval = reflect.ValueOf(&node{kind: basicLit, rval: reflect.New(typ.TypeOf()).Elem()})
@@ -1426,6 +1502,9 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				// Resolve source package symbol
 				if sym, ok := interp.srcPkg[pkg][name]; ok {
 					n.findex = sym.index
+					if sym.global {
+						n.level = globalFrame
+					}
 					n.val = sym.node
 					n.gen = nop
 					n.action = aGetSym
@@ -1440,7 +1519,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				if n.child[0].isType(sc) {
 					// Handle method as a function with receiver in 1st argument
 					n.val = m
-					n.findex = -1
+					n.findex = notInFrame
 					n.gen = nop
 					n.typ = &itype{}
 					*n.typ = *m.typ
@@ -1753,7 +1832,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			switch {
 			case n.rval.IsValid():
 				n.gen = nop
-				n.findex = -1
+				n.findex = notInFrame
 			case n.anc.kind == assignStmt && n.anc.action == aAssign:
 				dest := n.anc.child[childPos(n)-n.anc.nright]
 				n.typ = dest.typ
@@ -1780,6 +1859,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 				if sc.global {
 					// Global object allocation is already performed in GTA.
 					index = sc.sym[c.ident].index
+					c.level = globalFrame
 				} else {
 					index = sc.add(n.typ)
 					sc.sym[c.ident] = &symbol{index: index, kind: varSym, typ: n.typ}
@@ -1806,8 +1886,15 @@ func compDefineX(sc *scope, n *node) error {
 		if err != nil {
 			return err
 		}
+		for funtype.cat == valueT && funtype.val != nil {
+			// Retrieve original interpreter type from a wrapped function.
+			// Struct fields of function types are always wrapped in valueT to ensure
+			// their possible use in runtime. In that case, the val field retains the
+			// original interpreter type, which is used now.
+			funtype = funtype.val
+		}
 		if funtype.cat == valueT {
-			// Handle functions imported from runtime
+			// Handle functions imported from runtime.
 			for i := 0; i < funtype.rtype.NumOut(); i++ {
 				types = append(types, &itype{cat: valueT, rtype: funtype.rtype.Out(i)})
 			}
@@ -1831,7 +1918,7 @@ func compDefineX(sc *scope, n *node) error {
 		if n.child[0].ident == "_" {
 			n.child[l].gen = typeAssertStatus
 		} else {
-			n.child[l].gen = typeAssert2
+			n.child[l].gen = typeAssertLong
 		}
 		types = append(types, n.child[l].child[1].typ, sc.getType("bool"))
 		n.gen = nop
@@ -2263,7 +2350,7 @@ func isCall(n *node) bool {
 }
 
 func isBinCall(n *node) bool {
-	return n.kind == callExpr && n.child[0].typ.cat == valueT && n.child[0].typ.rtype.Kind() == reflect.Func
+	return isCall(n) && n.child[0].typ.cat == valueT && n.child[0].typ.rtype.Kind() == reflect.Func
 }
 
 func mustReturnValue(n *node) bool {
@@ -2279,7 +2366,7 @@ func mustReturnValue(n *node) bool {
 }
 
 func isRegularCall(n *node) bool {
-	return n.kind == callExpr && n.child[0].typ.cat == funcT
+	return isCall(n) && n.child[0].typ.cat == funcT
 }
 
 func variadicPos(n *node) int {
@@ -2360,10 +2447,10 @@ func gotoLabel(s *symbol) {
 	}
 }
 
-func compositeGenerator(n *node, typ *itype) (gen bltnGenerator) {
+func compositeGenerator(n *node, typ *itype, rtyp reflect.Type) (gen bltnGenerator) {
 	switch typ.cat {
 	case aliasT, ptrT:
-		gen = compositeGenerator(n, n.typ.val)
+		gen = compositeGenerator(n, n.typ.val, rtyp)
 	case arrayT:
 		gen = arrayLit
 	case mapT:
@@ -2386,11 +2473,23 @@ func compositeGenerator(n *node, typ *itype) (gen bltnGenerator) {
 			}
 		}
 	case valueT:
-		switch k := n.typ.rtype.Kind(); k {
+		if rtyp == nil {
+			rtyp = n.typ.rtype
+		}
+		switch k := rtyp.Kind(); k {
 		case reflect.Struct:
-			gen = compositeBinStruct
+			if n.nleft == 1 {
+				gen = compositeBinStruct
+			} else {
+				gen = compositeBinStructNotype
+			}
 		case reflect.Map:
+			// TODO(mpl): maybe needs a NoType version too
 			gen = compositeBinMap
+		case reflect.Ptr:
+			gen = compositeGenerator(n, typ, n.typ.val.rtype)
+		case reflect.Slice:
+			gen = compositeBinSlice
 		default:
 			log.Panic(n.cfgErrorf("compositeGenerator not implemented for type kind: %s", k))
 		}
@@ -2432,3 +2531,22 @@ func isValueUntyped(v reflect.Value) bool {
 	}
 	return t.String() == t.Kind().String()
 }
+
+// isArithmeticAction returns true if the node action is an arithmetic operator.
+func isArithmeticAction(n *node) bool {
+	switch n.action {
+	case aAdd, aAnd, aAndNot, aBitNot, aMul, aQuo, aRem, aShl, aShr, aSub, aXor:
+		return true
+	default:
+		return false
+	}
+}
+
+func isBoolAction(n *node) bool {
+	switch n.action {
+	case aEqual, aGreater, aGreaterEqual, aLand, aLor, aLower, aLowerEqual, aNot, aNotEqual:
+		return true
+	default:
+		return false
+	}
+}

interp/gta.go

@@ -115,6 +115,7 @@ func (interp *Interpreter) gta(root *node, rpath, importPath string) ([]*node, e
 					sc.sym[c.ident] = &symbol{index: sc.add(n.typ), kind: varSym, global: true, typ: n.typ, node: n}
 					continue
 				}
+				c.level = globalFrame
 
 				// redeclaration error
 				if sym.typ.node != nil && sym.typ.node.anc != nil {
@@ -145,7 +146,7 @@ func (interp *Interpreter) gta(root *node, rpath, importPath string) ([]*node, e
 					elementType := sc.getType(typeName)
 					if elementType == nil {
 						// Add type if necessary, so method can be registered
-						sc.sym[typeName] = &symbol{kind: typeSym, typ: &itype{name: typeName, path: rpath, incomplete: true, node: rtn.child[0], scope: sc}}
+						sc.sym[typeName] = &symbol{kind: typeSym, typ: &itype{name: typeName, path: importPath, incomplete: true, node: rtn.child[0], scope: sc}}
 						elementType = sc.sym[typeName].typ
 					}
 					rcvrtype = &itype{cat: ptrT, val: elementType, incomplete: elementType.incomplete, node: rtn, scope: sc}
@@ -154,7 +155,7 @@ func (interp *Interpreter) gta(root *node, rpath, importPath string) ([]*node, e
 					rcvrtype = sc.getType(typeName)
 					if rcvrtype == nil {
 						// Add type if necessary, so method can be registered
-						sc.sym[typeName] = &symbol{kind: typeSym, typ: &itype{name: typeName, path: rpath, incomplete: true, node: rtn, scope: sc}}
+						sc.sym[typeName] = &symbol{kind: typeSym, typ: &itype{name: typeName, path: importPath, incomplete: true, node: rtn, scope: sc}}
 						rcvrtype = sc.sym[typeName].typ
 					}
 				}
@@ -248,16 +249,19 @@ func (interp *Interpreter) gta(root *node, rpath, importPath string) ([]*node, e
 			typeName := n.child[0].ident
 			var typ *itype
 			if typ, err = nodeType(interp, sc, n.child[1]); err != nil {
+				err = nil
+				revisit = append(revisit, n)
 				return false
 			}
 
-			if n.child[1].kind == identExpr {
-				n.typ = &itype{cat: aliasT, val: typ, name: typeName, path: rpath, field: typ.field, incomplete: typ.incomplete, scope: sc, node: n.child[0]}
+			switch n.child[1].kind {
+			case identExpr, selectorExpr:
+				n.typ = &itype{cat: aliasT, val: typ, name: typeName, path: importPath, field: typ.field, incomplete: typ.incomplete, scope: sc, node: n.child[0]}
 				copy(n.typ.method, typ.method)
-			} else {
+			default:
 				n.typ = typ
 				n.typ.name = typeName
-				n.typ.path = rpath
+				n.typ.path = importPath
 			}
 
 			asImportName := filepath.Join(typeName, baseName)

interp/hooks.go

@@ -2,8 +2,6 @@ package interp
 
 import "reflect"
 
-const hooksPath = "github.com/traefik/yaegi"
-
 // convertFn is the signature of a symbol converter.
 type convertFn func(from, to reflect.Type) func(src, dest reflect.Value)
 

interp/interp.go

@@ -65,7 +65,8 @@ type frame struct {
 	// Located at start of struct to ensure proper aligment.
 	id uint64
 
-	anc  *frame          // ancestor frame (global space)
+	root *frame          // global space
+	anc  *frame          // ancestor frame (caller space)
 	data []reflect.Value // values
 
 	mutex     sync.RWMutex
@@ -80,8 +81,11 @@ func newFrame(anc *frame, len int, id uint64) *frame {
 		data: make([]reflect.Value, len),
 		id:   id,
 	}
-	if anc != nil {
+	if anc == nil {
+		f.root = f
+	} else {
 		f.done = anc.done
+		f.root = anc.root
 	}
 	return f
 }
@@ -93,6 +97,7 @@ func (f *frame) clone() *frame {
 	defer f.mutex.RUnlock()
 	return &frame{
 		anc:       f.anc,
+		root:      f.root,
 		data:      f.data,
 		deferred:  f.deferred,
 		recovered: f.recovered,
@@ -155,8 +160,9 @@ type Interpreter struct {
 }
 
 const (
-	mainID   = "main"
-	selfPath = "github.com/traefik/yaegi/interp"
+	mainID     = "main"
+	selfPrefix = "github.com/traefik/yaegi"
+	selfPath   = selfPrefix + "/interp"
 	// DefaultSourceName is the name used by default when the name of the input
 	// source file has not been specified for an Eval.
 	// TODO(mpl): something even more special as a name?
@@ -175,6 +181,7 @@ var Symbols = Exports{
 
 		"Interpreter": reflect.ValueOf((*Interpreter)(nil)),
 		"Options":     reflect.ValueOf((*Options)(nil)),
+		"Panic":       reflect.ValueOf((*Panic)(nil)),
 	},
 }
 
@@ -237,7 +244,7 @@ type Options struct {
 func New(options Options) *Interpreter {
 	i := Interpreter{
 		opt:      opt{context: build.Default},
-		frame:    &frame{data: []reflect.Value{}},
+		frame:    newFrame(nil, 0, 0),
 		fset:     token.NewFileSet(),
 		universe: initUniverse(),
 		scopes:   map[string]*scope{},
@@ -401,32 +408,59 @@ func (interp *Interpreter) EvalTest(path string) error {
 	return err
 }
 
-// Symbols returns a map of interpreter exported symbol values for the given path.
-func (interp *Interpreter) Symbols(path string) map[string]reflect.Value {
-	m := map[string]reflect.Value{}
-
+// Symbols returns a map of interpreter exported symbol values for the given
+// import path. If the argument is the empty string, all known symbols are
+// returned.
+func (interp *Interpreter) Symbols(importPath string) Exports {
+	m := map[string]map[string]reflect.Value{}
 	interp.mutex.RLock()
-	if interp.scopes[path] == nil {
-		interp.mutex.RUnlock()
-		return m
-	}
-	sym := interp.scopes[path].sym
-	interp.mutex.RUnlock()
+	defer interp.mutex.RUnlock()
 
-	for n, s := range sym {
-		if !canExport(n) {
-			// Skip private non-exported symbols.
+	for k, v := range interp.srcPkg {
+		if importPath != "" && k != importPath {
 			continue
 		}
-		switch s.kind {
-		case constSym:
-			m[n] = s.rval
-		case funcSym:
-			m[n] = genFunctionWrapper(s.node)(interp.frame)
-		case varSym:
-			m[n] = interp.frame.data[s.index]
+		syms := map[string]reflect.Value{}
+		for n, s := range v {
+			if !canExport(n) {
+				// Skip private non-exported symbols.
+				continue
+			}
+			switch s.kind {
+			case constSym:
+				syms[n] = s.rval
+			case funcSym:
+				syms[n] = genFunctionWrapper(s.node)(interp.frame)
+			case varSym:
+				syms[n] = interp.frame.data[s.index]
+			case typeSym:
+				syms[n] = reflect.New(s.typ.TypeOf())
+			}
+		}
+
+		if len(syms) > 0 {
+			m[k] = syms
+		}
+
+		if importPath != "" {
+			return m
 		}
 	}
+
+	if importPath != "" && len(m) > 0 {
+		return m
+	}
+
+	for k, v := range interp.binPkg {
+		if importPath != "" && k != importPath {
+			continue
+		}
+		m[k] = v
+		if importPath != "" {
+			return m
+		}
+	}
+
 	return m
 }
 
@@ -603,7 +637,7 @@ func (interp *Interpreter) getWrapper(t reflect.Type) reflect.Type {
 // they can be used in interpreted code.
 func (interp *Interpreter) Use(values Exports) {
 	for k, v := range values {
-		if k == hooksPath {
+		if k == selfPrefix {
 			interp.hooks.Parse(v)
 			continue
 		}
@@ -785,20 +819,28 @@ func (interp *Interpreter) REPL() (reflect.Value, error) {
 	}
 }
 
+func doPrompt(out io.Writer) func(v reflect.Value) {
+	return func(v reflect.Value) {
+		if v.IsValid() {
+			fmt.Fprintln(out, ":", v)
+		}
+		fmt.Fprint(out, "> ")
+	}
+}
+
 // getPrompt returns a function which prints a prompt only if input is a terminal.
 func getPrompt(in io.Reader, out io.Writer) func(reflect.Value) {
+	forcePrompt, _ := strconv.ParseBool(os.Getenv("YAEGI_PROMPT"))
+	if forcePrompt {
+		return doPrompt(out)
+	}
 	s, ok := in.(interface{ Stat() (os.FileInfo, error) })
 	if !ok {
 		return func(reflect.Value) {}
 	}
 	stat, err := s.Stat()
 	if err == nil && stat.Mode()&os.ModeCharDevice != 0 {
-		return func(v reflect.Value) {
-			if v.IsValid() {
-				fmt.Fprintln(out, ":", v)
-			}
-			fmt.Fprint(out, "> ")
-		}
+		return doPrompt(out)
 	}
 	return func(reflect.Value) {}
 }

interp/interp_consistent_test.go

@@ -43,6 +43,9 @@ func TestInterpConsistencyBuild(t *testing.T) {
 			file.Name() == "for7.go" || // expect error
 			file.Name() == "fun21.go" || // expect error
 			file.Name() == "fun22.go" || // expect error
+			file.Name() == "fun23.go" || // expect error
+			file.Name() == "fun24.go" || // expect error
+			file.Name() == "fun25.go" || // expect error
 			file.Name() == "if2.go" || // expect error
 			file.Name() == "import6.go" || // expect error
 			file.Name() == "init1.go" || // expect error
@@ -201,6 +204,11 @@ func TestInterpErrorConsistency(t *testing.T) {
 			expectedInterp: "6:2: not enough arguments in call to time.Date",
 			expectedExec:   "6:11: not enough arguments in call to time.Date",
 		},
+		{
+			fileName:       "fun23.go",
+			expectedInterp: "3:17: too many arguments to return",
+			expectedExec:   "3:17: too many arguments to return",
+		},
 		{
 			fileName:       "op1.go",
 			expectedInterp: "5:2: invalid operation: mismatched types int and float64",

interp/interp_eval_test.go

@@ -71,6 +71,27 @@ func TestEvalArithmetic(t *testing.T) {
 	})
 }
 
+func TestEvalShift(t *testing.T) {
+	i := interp.New(interp.Options{})
+	runTests(t, i, []testCase{
+		{src: "a, b, m := uint32(1), uint32(2), uint32(0); m = a + (1 << b)", res: "5"},
+		{src: "c := uint(1); d := uint(+(-(1 << c)))", res: "18446744073709551614"},
+		{src: "e, f := uint32(0), uint32(0); f = 1 << -(e * 2)", res: "1"},
+		{src: "p := uint(0xdead); byte((1 << (p & 7)) - 1)", res: "31"},
+		{pre: func() { eval(t, i, "const k uint = 1 << 17") }, src: "int(k)", res: "131072"},
+	})
+}
+
+func TestOpVarConst(t *testing.T) {
+	i := interp.New(interp.Options{})
+	runTests(t, i, []testCase{
+		{pre: func() { eval(t, i, "const a uint = 8 + 2") }, src: "a", res: "10"},
+		{src: "b := uint(5); a+b", res: "15"},
+		{src: "b := uint(5); b+a", res: "15"},
+		{src: "b := uint(5); b>a", res: "false"},
+	})
+}
+
 func TestEvalStar(t *testing.T) {
 	i := interp.New(interp.Options{})
 	runTests(t, i, []testCase{
@@ -89,6 +110,7 @@ func TestEvalAssign(t *testing.T) {
 		{src: "f := int64(3.2)", err: "1:39: cannot convert expression of type float64 to type int64"},
 		{src: "g := 1; g <<= 8", res: "256"},
 		{src: "h := 1; h >>= 8", res: "0"},
+		{src: "i := 1; j := &i; (*j) = 2", res: "2"},
 	})
 }
 
@@ -423,19 +445,15 @@ func TestEvalSliceExpression(t *testing.T) {
 		{src: `a := []int{0,1,2}[:]`, res: "[0 1 2]"},
 		{src: `a := []int{0,1,2,3}[1:3:4]`, res: "[1 2]"},
 		{src: `a := []int{0,1,2,3}[:3:4]`, res: "[0 1 2]"},
-		{src: `ar := [3]int{0,1,2}
-			   a := ar[1:3]`, res: "[1 2]"},
+		{src: `ar := [3]int{0,1,2}; a := ar[1:3]`, res: "[1 2]"},
 		{src: `a := (&[3]int{0,1,2})[1:3]`, res: "[1 2]"},
 		{src: `a := (&[3]int{0,1,2})[1:3]`, res: "[1 2]"},
 		{src: `s := "hello"[1:3]`, res: "el"},
-		{src: `str := "hello"
-			   s := str[1:3]`, res: "el"},
+		{src: `str := "hello"; s := str[1:3]`, res: "el"},
 		{src: `a := int(1)[0:1]`, err: "1:33: cannot slice type int"},
-		{src: `a := ([3]int{0,1,2})[1:3]`, err: "1:33: cannot slice type [3]int"},
 		{src: `a := (&[]int{0,1,2,3})[1:3]`, err: "1:33: cannot slice type *[]int"},
 		{src: `a := "hello"[1:3:4]`, err: "1:45: invalid operation: 3-index slice of string"},
-		{src: `ar := [3]int{0,1,2}
-			   a := ar[:4]`, err: "2:16: index int is out of bounds"},
+		{src: `ar := [3]int{0,1,2}; a := ar[:4]`, err: "1:58: index int is out of bounds"},
 		{src: `a := []int{0,1,2,3}[1::4]`, err: "1:49: 2nd index required in 3-index slice"},
 		{src: `a := []int{0,1,2,3}[1:3:]`, err: "1:51: 3rd index required in 3-index slice"},
 		{src: `a := []int{0,1,2}[3:1]`, err: "invalid index values, must be low <= high <= max"},
@@ -986,6 +1004,9 @@ func TestConcurrentEvals(t *testing.T) {
 // called by EvalWithContext is sequential. And that there is no data race for the
 // interp package global vars or the interpreter fields in this case.
 func TestConcurrentEvals2(t *testing.T) {
+	if testing.Short() {
+		return
+	}
 	pin, pout := io.Pipe()
 	defer func() {
 		_ = pin.Close()
@@ -1045,6 +1066,9 @@ func TestConcurrentEvals2(t *testing.T) {
 // - when calling Interpreter.Use, the symbols given as argument should be
 // copied when being inserted into interp.binPkg, and not directly used as-is.
 func TestConcurrentEvals3(t *testing.T) {
+	if testing.Short() {
+		return
+	}
 	allDone := make(chan bool)
 	runREPL := func() {
 		done := make(chan error)
@@ -1123,6 +1147,9 @@ func TestConcurrentComposite2(t *testing.T) {
 }
 
 func testConcurrentComposite(t *testing.T, filePath string) {
+	if testing.Short() {
+		return
+	}
 	pin, pout := io.Pipe()
 	i := interp.New(interp.Options{Stdout: pout})
 	i.Use(stdlib.Symbols)
@@ -1160,6 +1187,9 @@ func testConcurrentComposite(t *testing.T, filePath string) {
 }
 
 func TestEvalScanner(t *testing.T) {
+	if testing.Short() {
+		return
+	}
 	type testCase struct {
 		desc      string
 		src       []string
@@ -1331,3 +1361,94 @@ func applyCIMultiplier(timeout time.Duration) time.Duration {
 	}
 	return time.Duration(float64(timeout) * CITimeoutMultiplier)
 }
+
+func TestREPLDivision(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+	_ = os.Setenv("YAEGI_PROMPT", "1")
+	defer func() {
+		_ = os.Setenv("YAEGI_PROMPT", "0")
+	}()
+	allDone := make(chan bool)
+	runREPL := func() {
+		done := make(chan error)
+		pinin, poutin := io.Pipe()
+		pinout, poutout := io.Pipe()
+		i := interp.New(interp.Options{Stdin: pinin, Stdout: poutout})
+		i.Use(stdlib.Symbols)
+
+		go func() {
+			_, _ = i.REPL()
+		}()
+
+		defer func() {
+			_ = pinin.Close()
+			_ = poutin.Close()
+			_ = pinout.Close()
+			_ = poutout.Close()
+			allDone <- true
+		}()
+
+		input := []string{
+			`1/1`,
+			`7/3`,
+			`16/5`,
+			`3./2`, // float
+		}
+		output := []string{
+			`1`,
+			`2`,
+			`3`,
+			`1.5`,
+		}
+
+		go func() {
+			sc := bufio.NewScanner(pinout)
+			k := 0
+			for sc.Scan() {
+				l := sc.Text()
+				if l != "> : "+output[k] {
+					done <- fmt.Errorf("unexpected output, want %q, got %q", output[k], l)
+					return
+				}
+				k++
+				if k > 3 {
+					break
+				}
+			}
+			done <- nil
+		}()
+
+		for _, v := range input {
+			in := strings.NewReader(v + "\n")
+			if _, err := io.Copy(poutin, in); err != nil {
+				t.Fatal(err)
+			}
+			select {
+			case err := <-done:
+				if err != nil {
+					t.Fatal(err)
+				}
+				return
+			default:
+				time.Sleep(time.Second)
+			}
+		}
+
+		if err := <-done; err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	go func() {
+		runREPL()
+	}()
+
+	timeout := time.NewTimer(10 * time.Second)
+	select {
+	case <-allDone:
+	case <-timeout.C:
+		t.Fatal("timeout")
+	}
+}

interp/op.go

@@ -701,7 +701,16 @@ func quoConst(n *node) {
 	n.rval = reflect.New(t).Elem()
 	switch {
 	case isConst:
-		v := constant.BinaryOp(vConstantValue(v0), token.QUO, vConstantValue(v1))
+		var operator token.Token
+		// When the result of the operation is expected to be an int (because both
+		// operands are ints), we want to force the type of the whole expression to be an
+		// int (and not a float), which is achieved by using the QUO_ASSIGN operator.
+		if n.typ.untyped && isInt(n.typ.rtype) {
+			operator = token.QUO_ASSIGN
+		} else {
+			operator = token.QUO
+		}
+		v := constant.BinaryOp(vConstantValue(v0), operator, vConstantValue(v1))
 		n.rval.Set(reflect.ValueOf(v))
 	case isComplex(t):
 		n.rval.SetComplex(vComplex(v0) / vComplex(v1))
@@ -1957,10 +1966,10 @@ func bitNotConst(n *node) {
 	case isConst:
 		v := constant.UnaryOp(token.XOR, vConstantValue(v0), 0)
 		n.rval.Set(reflect.ValueOf(v))
-	case isInt(t):
-		n.rval.SetInt(^v0.Int())
 	case isUint(t):
 		n.rval.SetUint(^v0.Uint())
+	case isInt(t):
+		n.rval.SetInt(^v0.Int())
 	}
 }
 
@@ -1976,10 +1985,10 @@ func negConst(n *node) {
 	case isConst:
 		v := constant.UnaryOp(token.SUB, vConstantValue(v0), 0)
 		n.rval.Set(reflect.ValueOf(v))
-	case isInt(t):
-		n.rval.SetInt(-v0.Int())
 	case isUint(t):
 		n.rval.SetUint(-v0.Uint())
+	case isInt(t):
+		n.rval.SetInt(-v0.Int())
 	case isFloat(t):
 		n.rval.SetFloat(-v0.Float())
 	case isComplex(t):
@@ -2015,10 +2024,10 @@ func posConst(n *node) {
 	case isConst:
 		v := constant.UnaryOp(token.ADD, vConstantValue(v0), 0)
 		n.rval.Set(reflect.ValueOf(v))
-	case isInt(t):
-		n.rval.SetInt(+v0.Int())
 	case isUint(t):
 		n.rval.SetUint(+v0.Uint())
+	case isInt(t):
+		n.rval.SetInt(+v0.Int())
 	case isFloat(t):
 		n.rval.SetFloat(+v0.Float())
 	case isComplex(t):

interp/scope.go

@@ -72,26 +72,28 @@ type symbol struct {
 // execution to the index in frame, created exactly from the types layout.
 //
 type scope struct {
-	anc         *scope             // Ancestor upper scope
+	anc         *scope             // ancestor upper scope
+	child       []*scope           // included scopes
 	def         *node              // function definition node this scope belongs to, or nil
 	loop        *node              // loop exit node for break statement
 	loopRestart *node              // loop restart node for continue statement
 	pkgID       string             // unique id of package in which scope is defined
-	types       []reflect.Type     // Frame layout, may be shared by same level scopes
-	level       int                // Frame level: number of frame indirections to access var during execution
-	sym         map[string]*symbol // Map of symbols defined in this current scope
+	types       []reflect.Type     // frame layout, may be shared by same level scopes
+	level       int                // frame level: number of frame indirections to access var during execution
+	sym         map[string]*symbol // map of symbols defined in this current scope
 	global      bool               // true if scope refers to global space (single frame for universe and package level scopes)
 	iota        int                // iota value in this scope
 }
 
-// push creates a new scope and chain it to the current one.
+// push creates a new child scope and chain it to the current one.
 func (s *scope) push(indirect bool) *scope {
-	sc := scope{anc: s, level: s.level, sym: map[string]*symbol{}}
+	sc := &scope{anc: s, level: s.level, sym: map[string]*symbol{}}
+	s.child = append(s.child, sc)
 	if indirect {
 		sc.types = []reflect.Type{}
 		sc.level = s.level + 1
 	} else {
-		// propagate size, types, def and global as scopes at same level share the same frame
+		// Propagate size, types, def and global as scopes at same level share the same frame.
 		sc.types = s.types
 		sc.def = s.def
 		sc.global = s.global
@@ -99,7 +101,7 @@ func (s *scope) push(indirect bool) *scope {
 	}
 	// inherit loop state and pkgID from ancestor
 	sc.loop, sc.loopRestart, sc.pkgID = s.loop, s.loopRestart, s.pkgID
-	return &sc
+	return sc
 }
 
 func (s *scope) pushBloc() *scope { return s.push(false) }
@@ -107,12 +109,20 @@ func (s *scope) pushFunc() *scope { return s.push(true) }
 
 func (s *scope) pop() *scope {
 	if s.level == s.anc.level {
-		// propagate size and types, as scopes at same level share the same frame
+		// Propagate size and types, as scopes at same level share the same frame.
 		s.anc.types = s.types
 	}
 	return s.anc
 }
 
+func (s *scope) upperLevel() *scope {
+	level := s.level
+	for s != nil && s.level == level {
+		s = s.anc
+	}
+	return s
+}
+
 // lookup searches for a symbol in the current scope, and upper ones if not found
 // it returns the symbol, the number of indirections level from the current scope
 // and status (false if no result).
@@ -120,6 +130,9 @@ func (s *scope) lookup(ident string) (*symbol, int, bool) {
 	level := s.level
 	for {
 		if sym, ok := s.sym[ident]; ok {
+			if sym.global {
+				return sym, globalFrame, true
+			}
 			return sym, level - s.level, true
 		}
 		if s.anc == nil {
@@ -130,6 +143,20 @@ func (s *scope) lookup(ident string) (*symbol, int, bool) {
 	return nil, 0, false
 }
 
+// lookdown searches for a symbol in the current scope and included ones, recursively.
+// It returns the first found symbol and true, or nil and false.
+func (s *scope) lookdown(ident string) (*symbol, bool) {
+	if sym, ok := s.sym[ident]; ok {
+		return sym, true
+	}
+	for _, c := range s.child {
+		if sym, ok := c.lookdown(ident); ok {
+			return sym, true
+		}
+	}
+	return nil, false
+}
+
 func (s *scope) rangeChanType(n *node) *itype {
 	if sym, _, found := s.lookup(n.child[1].ident); found {
 		if t := sym.typ; len(n.child) == 3 && t != nil && (t.cat == chanT || t.cat == chanRecvT) {

interp/src.go

@@ -33,17 +33,12 @@ func (interp *Interpreter) importSrc(rPath, importPath string, skipTest bool) (s
 			rPath = "."
 		}
 		dir = filepath.Join(filepath.Dir(interp.name), rPath, importPath)
-	} else {
-		var root string
-		if rPath == mainID {
-			root, err = interp.rootFromSourceLocation()
-			if err != nil {
-				return "", err
-			}
-		} else {
-			root = rPath
+	} else if dir, rPath, err = pkgDir(interp.context.GOPATH, rPath, importPath); err != nil {
+		// Try again, assuming a root dir at the source location.
+		if rPath, err = interp.rootFromSourceLocation(); err != nil {
+			return "", err
 		}
-		if dir, rPath, err = pkgDir(interp.context.GOPATH, root, importPath); err != nil {
+		if dir, rPath, err = pkgDir(interp.context.GOPATH, rPath, importPath); err != nil {
 			return "", err
 		}
 	}

interp/type.go

@@ -166,56 +166,68 @@ func nodeType(interp *Interpreter, sc *scope, n *node) (*itype, error) {
 
 	case arrayType:
 		t.cat = arrayT
-		if len(n.child) > 1 {
-			v := n.child[0].rval
-			switch {
-			case v.IsValid():
-				// constant size
-				if isConstantValue(v.Type()) {
-					c := v.Interface().(constant.Value)
-					t.size = constToInt(c)
-				} else {
-					t.size = int(v.Int())
-				}
-			case n.child[0].kind == ellipsisExpr:
-				// [...]T expression
-				t.size = arrayTypeLen(n.anc)
-			default:
-				if sym, _, ok := sc.lookup(n.child[0].ident); ok {
-					if sym.kind != constSym {
-						return nil, n.child[0].cfgErrorf("non-constant array bound %q", n.child[0].ident)
-					}
-					// Resolve symbol to get size value
-					if sym.typ != nil && sym.typ.cat == intT {
-						if v, ok := sym.rval.Interface().(int); ok {
-							t.size = v
-						} else if c, ok := sym.rval.Interface().(constant.Value); ok {
-							t.size = constToInt(c)
-						} else {
-							t.incomplete = true
-						}
-					} else {
-						t.incomplete = true
-					}
-				} else {
-					// Evaluate constant array size expression
-					if _, err = interp.cfg(n.child[0], sc.pkgID); err != nil {
-						return nil, err
-					}
-					t.incomplete = true
-				}
-			}
-			if t.val, err = nodeType(interp, sc, n.child[1]); err != nil {
-				return nil, err
-			}
-			t.sizedef = true
-			t.incomplete = t.incomplete || t.val.incomplete
-		} else {
-			if t.val, err = nodeType(interp, sc, n.child[0]); err != nil {
+		c0 := n.child[0]
+		if len(n.child) == 1 {
+			// Array size is not defined.
+			if t.val, err = nodeType(interp, sc, c0); err != nil {
 				return nil, err
 			}
 			t.incomplete = t.val.incomplete
+			break
 		}
+		// Array size is defined.
+		switch v := c0.rval; {
+		case v.IsValid():
+			// Size if defined by a constant litteral value.
+			if isConstantValue(v.Type()) {
+				c := v.Interface().(constant.Value)
+				t.size = constToInt(c)
+			} else {
+				t.size = int(v.Int())
+			}
+		case c0.kind == ellipsisExpr:
+			// [...]T expression, get size from the length of composite array.
+			t.size = arrayTypeLen(n.anc)
+		case c0.kind == identExpr:
+			sym, _, ok := sc.lookup(c0.ident)
+			if !ok {
+				t.incomplete = true
+				break
+			}
+			// Size is defined by a symbol which must be a constant integer.
+			if sym.kind != constSym {
+				return nil, c0.cfgErrorf("non-constant array bound %q", c0.ident)
+			}
+			if sym.typ == nil || sym.typ.cat != intT {
+				t.incomplete = true
+				break
+			}
+			if v, ok := sym.rval.Interface().(int); ok {
+				t.size = v
+				break
+			}
+			if c, ok := sym.rval.Interface().(constant.Value); ok {
+				t.size = constToInt(c)
+				break
+			}
+			t.incomplete = true
+		default:
+			// Size is defined by a numeric constant expression.
+			if _, err = interp.cfg(c0, sc.pkgID); err != nil {
+				return nil, err
+			}
+			v, ok := c0.rval.Interface().(constant.Value)
+			if !ok {
+				t.incomplete = true
+				break
+			}
+			t.size = constToInt(v)
+		}
+		if t.val, err = nodeType(interp, sc, n.child[1]); err != nil {
+			return nil, err
+		}
+		t.sizedef = true
+		t.incomplete = t.incomplete || t.val.incomplete
 
 	case basicLit:
 		switch v := n.rval.Interface().(type) {
@@ -545,12 +557,12 @@ func nodeType(interp *Interpreter, sc *scope, n *node) (*itype, error) {
 			if v, ok := pkg[name]; ok {
 				t.cat = valueT
 				t.rtype = v.Type()
-				if isBinType(v) { // a bin type is encoded as a pointer on nil value
+				if isBinType(v) {
+					// A bin type is encoded as a pointer on a typed nil value.
 					t.rtype = t.rtype.Elem()
 				}
 			} else {
 				err = n.cfgErrorf("undefined selector %s.%s", lt.path, name)
-				panic(err)
 			}
 		case srcPkgT:
 			pkg := interp.srcPkg[lt.path]
@@ -725,7 +737,7 @@ func (t *itype) finalize() (*itype, error) {
 }
 
 // ReferTo returns true if the type contains a reference to a
-// full type name. It allows to asses a type recursive status.
+// full type name. It allows to assess a type recursive status.
 func (t *itype) referTo(name string, seen map[*itype]bool) bool {
 	if t.path+"/"+t.name == name {
 		return true
@@ -915,7 +927,23 @@ func (t *itype) assignableTo(o *itype) bool {
 	if t.isNil() && o.hasNil() || o.isNil() && t.hasNil() {
 		return true
 	}
-	return t.TypeOf().AssignableTo(o.TypeOf())
+
+	if t.TypeOf().AssignableTo(o.TypeOf()) {
+		return true
+	}
+
+	n := t.node
+	if n == nil || !n.rval.IsValid() {
+		return false
+	}
+	con, ok := n.rval.Interface().(constant.Value)
+	if !ok {
+		return false
+	}
+	if con == nil || !isConstType(o) {
+		return false
+	}
+	return representableConst(con, o.TypeOf())
 }
 
 // convertibleTo returns true if t is convertible to o.
@@ -924,7 +952,7 @@ func (t *itype) convertibleTo(o *itype) bool {
 		return true
 	}
 
-	// unsafe checkes
+	// unsafe checks
 	tt, ot := t.TypeOf(), o.TypeOf()
 	if (tt.Kind() == reflect.Ptr || tt.Kind() == reflect.Uintptr) && ot.Kind() == reflect.UnsafePointer {
 		return true
@@ -1180,7 +1208,11 @@ func (t *itype) lookupBinField(name string) (s reflect.StructField, index []int,
 	if !isStruct(t) {
 		return
 	}
-	s, ok = t.TypeOf().FieldByName(name)
+	rt := t.rtype
+	if t.cat == valueT && rt.Kind() == reflect.Ptr {
+		rt = rt.Elem()
+	}
+	s, ok = rt.FieldByName(name)
 	if !ok {
 		for i, f := range t.field {
 			if f.embed {

interp/typecheck.go

@@ -91,7 +91,10 @@ func (check typecheck) addressExpr(n *node) error {
 		case selectorExpr:
 			c0 = c0.child[1]
 			continue
-		case indexExpr:
+		case starExpr:
+			c0 = c0.child[0]
+			continue
+		case indexExpr, sliceExpr:
 			c := c0.child[0]
 			if isArray(c.typ) || isMap(c.typ) {
 				c0 = c
@@ -101,7 +104,7 @@ func (check typecheck) addressExpr(n *node) error {
 			found = true
 			continue
 		}
-		return n.cfgErrorf("invalid operation: cannot take address of %s", c0.typ.id())
+		return n.cfgErrorf("invalid operation: cannot take address of %s [kind: %s]", c0.typ.id(), kinds[c0.kind])
 	}
 	return nil
 }
@@ -148,7 +151,7 @@ func (check typecheck) shift(n *node) error {
 	t0, t1 := c0.typ.TypeOf(), c1.typ.TypeOf()
 
 	var v0 constant.Value
-	if c0.typ.untyped {
+	if c0.typ.untyped && c0.rval.IsValid() {
 		v0 = constant.ToInt(c0.rval.Interface().(constant.Value))
 		c0.rval = reflect.ValueOf(v0)
 	}
@@ -214,6 +217,7 @@ var binaryOpPredicates = opPredicates{
 // binaryExpr type checks a binary expression.
 func (check typecheck) binaryExpr(n *node) error {
 	c0, c1 := n.child[0], n.child[1]
+
 	a := n.action
 	if isAssignAction(a) {
 		a--
@@ -223,6 +227,21 @@ func (check typecheck) binaryExpr(n *node) error {
 		return check.shift(n)
 	}
 
+	switch n.action {
+	case aRem:
+		if zeroConst(c1) {
+			return n.cfgErrorf("invalid operation: division by zero")
+		}
+	case aQuo:
+		if zeroConst(c1) {
+			return n.cfgErrorf("invalid operation: division by zero")
+		}
+		if c0.rval.IsValid() && c1.rval.IsValid() {
+			// Avoid constant conversions below to ensure correct constant integer quotient.
+			return nil
+		}
+	}
+
 	_ = check.convertUntyped(c0, c1.typ)
 	_ = check.convertUntyped(c1, c0.typ)
 
@@ -238,16 +257,13 @@ func (check typecheck) binaryExpr(n *node) error {
 	if err := check.op(binaryOpPredicates, a, n, c0, t0); err != nil {
 		return err
 	}
-
-	switch n.action {
-	case aQuo, aRem:
-		if (c0.typ.untyped || isInt(t0)) && c1.typ.untyped && constant.Sign(c1.rval.Interface().(constant.Value)) == 0 {
-			return n.cfgErrorf("invalid operation: division by zero")
-		}
-	}
 	return nil
 }
 
+func zeroConst(n *node) bool {
+	return n.typ.untyped && constant.Sign(n.rval.Interface().(constant.Value)) == 0
+}
+
 func (check typecheck) index(n *node, max int) error {
 	if err := check.convertUntyped(n, &itype{cat: intT, name: "int"}); err != nil {
 		return err
@@ -483,9 +499,7 @@ func (check typecheck) sliceExpr(n *node) error {
 	case reflect.Array:
 		valid = true
 		l = t.Len()
-		if c.kind != selectorExpr && (c.sym == nil || c.sym.kind != varSym) {
-			return c.cfgErrorf("cannot slice type %s", c.typ.id())
-		}
+		// TODO(marc): check addressable status of array object (i.e. composite arrays are not).
 	case reflect.Slice:
 		valid = true
 	case reflect.Ptr:
@@ -618,16 +632,13 @@ func (check typecheck) conversion(n *node, typ *itype) error {
 	if !ok {
 		return n.cfgErrorf("cannot convert expression of type %s to type %s", n.typ.id(), typ.id())
 	}
-
-	if n.typ.untyped {
-		if isInterface(typ) || c != nil && !isConstType(typ) {
-			typ = n.typ.defaultType()
-		}
-		if err := check.convertUntyped(n, typ); err != nil {
-			return err
-		}
+	if !n.typ.untyped || c == nil {
+		return nil
 	}
-	return nil
+	if isInterface(typ) || !isConstType(typ) {
+		typ = n.typ.defaultType()
+	}
+	return check.convertUntyped(n, typ)
 }
 
 type param struct {
@@ -1040,24 +1051,10 @@ func (check typecheck) convertUntyped(n *node, typ *itype) error {
 		return convErr
 	}
 
-	isFloatToIntDivision := false
 	if err := check.representable(n, rtyp); err != nil {
-		if !isInt(rtyp) || n.action != aQuo {
-			return err
-		}
-		// retry in the case of a division, and pretend we want a float. Because if we
-		// can represent a float, then it follows that we can represent the integer
-		// part of that float as an int.
-		if err := check.representable(n, reflect.TypeOf(1.0)); err != nil {
-			return err
-		}
-		isFloatToIntDivision = true
-	}
-	if isFloatToIntDivision {
-		n.rval, err = check.convertConstFloatToInt(n.rval)
-	} else {
-		n.rval, err = check.convertConst(n.rval, rtyp)
+		return err
 	}
+	n.rval, err = check.convertConst(n.rval, rtyp)
 	if err != nil {
 		if errors.Is(err, errCantConvert) {
 			return convErr
@@ -1099,22 +1096,6 @@ func (check typecheck) representable(n *node, t reflect.Type) error {
 	return nil
 }
 
-func (check typecheck) convertConstFloatToInt(v reflect.Value) (reflect.Value, error) {
-	if !v.IsValid() {
-		return v, errors.New("invalid float reflect value")
-	}
-	c, ok := v.Interface().(constant.Value)
-	if !ok {
-		return v, errors.New("unexpected non-constant value")
-	}
-
-	if constant.ToFloat(c).Kind() != constant.Float {
-		return v, errors.New("const value cannot be converted to float")
-	}
-	fl, _ := constant.Float64Val(c)
-	return reflect.ValueOf(int(fl)).Convert(reflect.TypeOf(1.0)), nil
-}
-
 func (check typecheck) convertConst(v reflect.Value, t reflect.Type) (reflect.Value, error) {
 	if !v.IsValid() {
 		// TODO(nick): This should be an error as the const is in the frame which is undesirable.

interp/value.go

@@ -5,8 +5,15 @@ import (
 	"reflect"
 )
 
+const (
+	notInFrame  = -1 // value of node.findex for literal values (not in frame)
+	globalFrame = -1 // value of node.level for global symbols
+)
+
 func valueGenerator(n *node, i int) func(*frame) reflect.Value {
 	switch n.level {
+	case globalFrame:
+		return func(f *frame) reflect.Value { return valueOf(f.root.data, i) }
 	case 0:
 		return func(f *frame) reflect.Value { return valueOf(f.data, i) }
 	case 1:
@@ -33,6 +40,30 @@ func valueOf(data []reflect.Value, i int) reflect.Value {
 	return reflect.Value{}
 }
 
+func genValueBinMethodOnInterface(n *node, defaultGen func(*frame) reflect.Value) func(*frame) reflect.Value {
+	if n == nil || n.child == nil || n.child[0] == nil ||
+		n.child[0].child == nil || n.child[0].child[0] == nil {
+		return defaultGen
+	}
+	if n.child[0].child[1] == nil || n.child[0].child[1].ident == "" {
+		return defaultGen
+	}
+	value0 := genValue(n.child[0].child[0])
+
+	return func(f *frame) reflect.Value {
+		val, ok := value0(f).Interface().(valueInterface)
+		if !ok {
+			return defaultGen(f)
+		}
+		typ := val.node.typ
+		if typ.node != nil || typ.cat != valueT {
+			return defaultGen(f)
+		}
+		meth, _ := typ.rtype.MethodByName(n.child[0].child[1].ident)
+		return meth.Func
+	}
+}
+
 func genValueRecvIndirect(n *node) func(*frame) reflect.Value {
 	v := genValueRecv(n)
 	return func(f *frame) reflect.Value { return v(f).Elem() }
@@ -55,6 +86,35 @@ func genValueRecv(n *node) func(*frame) reflect.Value {
 	}
 }
 
+func genValueBinRecv(n *node, recv *receiver) func(*frame) reflect.Value {
+	value := genValue(n)
+	binValue := genValue(recv.node)
+
+	v := func(f *frame) reflect.Value {
+		if def, ok := value(f).Interface().(*node); ok {
+			if def != nil && def.recv != nil && def.recv.val.IsValid() {
+				return def.recv.val
+			}
+		}
+
+		ival, _ := binValue(f).Interface().(valueInterface)
+		return ival.value
+	}
+
+	fi := recv.index
+	if len(fi) == 0 {
+		return v
+	}
+
+	return func(f *frame) reflect.Value {
+		r := v(f)
+		if r.Kind() == reflect.Ptr {
+			r = r.Elem()
+		}
+		return r.FieldByIndex(fi)
+	}
+}
+
 func genValueRecvInterfacePtr(n *node) func(*frame) reflect.Value {
 	v := genValue(n.recv.node)
 	fi := n.recv.index
@@ -118,18 +178,16 @@ func genValue(n *node) func(*frame) reflect.Value {
 			return func(f *frame) reflect.Value { return v }
 		}
 		if n.sym != nil {
-			if n.sym.index < 0 {
+			i := n.sym.index
+			if i < 0 {
 				return genValue(n.sym.node)
 			}
-			i := n.sym.index
 			if n.sym.global {
-				return func(f *frame) reflect.Value {
-					return n.interp.frame.data[i]
-				}
+				return func(f *frame) reflect.Value { return f.root.data[i] }
 			}
 			return valueGenerator(n, i)
 		}
-		if n.findex < 0 {
+		if n.findex == notInFrame {
 			var v reflect.Value
 			if w, ok := n.val.(reflect.Value); ok {
 				v = w
@@ -244,6 +302,17 @@ func genValueOutput(n *node, t reflect.Type) func(*frame) reflect.Value {
 	return value
 }
 
+func valueInterfaceValue(v reflect.Value) reflect.Value {
+	for {
+		vv, ok := v.Interface().(valueInterface)
+		if !ok {
+			break
+		}
+		v = vv.value
+	}
+	return v
+}
+
 func genValueInterfaceValue(n *node) func(*frame) reflect.Value {
 	value := genValue(n)
 
@@ -254,7 +323,7 @@ func genValueInterfaceValue(n *node) func(*frame) reflect.Value {
 			v.Set(zeroInterfaceValue())
 			v = value(f)
 		}
-		return v.Interface().(valueInterface).value
+		return valueInterfaceValue(v)
 	}
 }
 
@@ -342,6 +411,10 @@ func vInt(v reflect.Value) (i int64) {
 }
 
 func vUint(v reflect.Value) (i uint64) {
+	if c := vConstantValue(v); c != nil {
+		i, _ = constant.Uint64Val(constant.ToInt(c))
+		return i
+	}
 	switch v.Type().Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		i = uint64(v.Int())

stdlib/go1_15_archive_tar.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract archive/tar'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_archive_zip.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract archive/zip'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_bufio.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract bufio'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_bytes.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract bytes'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_compress_bzip2.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract compress/bzip2'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_compress_flate.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract compress/flate'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_compress_gzip.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract compress/gzip'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_compress_lzw.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract compress/lzw'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_compress_zlib.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract compress/zlib'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_container_heap.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract container/heap'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_container_list.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract container/list'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_container_ring.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract container/ring'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_context.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract context'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_aes.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/aes'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_cipher.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/cipher'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib