fix: use the import path for types

When running GTA, the type `path` was set to `rpath`. This equates to the package path (`github.com/traefik/yaegi`) in most cases. In the vendored case the `rpath` is the sub package path `something/vendor/github.com/traefik/yaegi` causing issues in typecheck and likely further down the line. By using the `importPath` it makes this consistent.

**Note:** I have no clue how to test this decently. I am open to options here.

Potentially Fixes #916

_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/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/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/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

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

internal/cmd/extract/extract.go

@@ -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 {

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:
+			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.Init != nil && a.Post == nil:
+			case a.Cond != nil && a.Init == nil && a.Post == nil:
 				kind = forStmt2
-				case a.Init == nil && a.Post != nil:
+			case a.Cond != nil && a.Init != nil && a.Post == nil:
 				kind = forStmt3
-				default:
+			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 +66,41 @@ 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 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
@@ -285,11 +320,7 @@ 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()
 
@@ -447,7 +478,7 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 			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
 				}
 			}
 
@@ -644,7 +675,12 @@ 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")
@@ -860,7 +896,12 @@ func (interp *Interpreter) cfg(root *node, importPath string) ([]*node, error) {
 					n.gen = nop
 					n.findex = -1
 					n.typ = c0.typ
+					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
@@ -1005,7 +1046,14 @@ 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")
@@ -1024,7 +1072,7 @@ 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")
@@ -1046,7 +1094,14 @@ 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")
@@ -1066,7 +1121,7 @@ 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
@@ -1074,7 +1129,7 @@ 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")
@@ -2467,3 +2522,12 @@ func isArithmeticAction(n *node) bool {
 		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

@@ -145,7 +145,7 @@ 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 +154,7 @@ 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
 					}
 				}
@@ -254,12 +254,12 @@ func (interp *Interpreter) gta(root *node, rpath, importPath string) ([]*node, e
 			}
 
 			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]}
+				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 {
 				n.typ = typ
 				n.typ.name = typeName
-				n.typ.path = rpath
+				n.typ.path = importPath
 			}
 
 			asImportName := filepath.Join(typeName, baseName)

interp/interp_eval_test.go

@@ -71,6 +71,17 @@ 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 TestEvalStar(t *testing.T) {
 	i := interp.New(interp.Options{})
 	runTests(t, i, []testCase{

interp/run.go

@@ -108,10 +108,53 @@ func (interp *Interpreter) run(n *node, cf *frame) {
 	runCfg(n.start, f)
 }
 
+// originalExecNode looks in the tree of nodes for the node which has exec,
+// aside from n, in order to know where n "inherited" that exec from.
+func originalExecNode(n *node, exec bltn) *node {
+	execAddr := reflect.ValueOf(exec).Pointer()
+	var originalNode *node
+	seen := make(map[int64]struct{})
+	root := n
+	for {
+		root = root.anc
+		if root == nil {
+			break
+		}
+		if _, ok := seen[root.index]; ok {
+			continue
+		}
+
+		root.Walk(func(wn *node) bool {
+			if _, ok := seen[wn.index]; ok {
+				return true
+			}
+			seen[wn.index] = struct{}{}
+			if wn.index == n.index {
+				return true
+			}
+			if wn.exec == nil {
+				return true
+			}
+			if reflect.ValueOf(wn.exec).Pointer() == execAddr {
+				originalNode = wn
+				return false
+			}
+			return true
+		}, nil)
+
+		if originalNode != nil {
+			break
+		}
+	}
+
+	return originalNode
+}
+
 // Functions set to run during execution of CFG.
 
 // runCfg executes a node AST by walking its CFG and running node builtin at each step.
 func runCfg(n *node, f *frame) {
+	var exec bltn
 	defer func() {
 		f.mutex.Lock()
 		f.recovered = recover()
@@ -119,14 +162,18 @@ func runCfg(n *node, f *frame) {
 			val[0].Call(val[1:])
 		}
 		if f.recovered != nil {
-			fmt.Println(n.cfgErrorf("panic"))
+			oNode := originalExecNode(n, exec)
+			if oNode == nil {
+				oNode = n
+			}
+			fmt.Println(oNode.cfgErrorf("panic"))
 			f.mutex.Unlock()
 			panic(f.recovered)
 		}
 		f.mutex.Unlock()
 	}()
 
-	for exec := n.exec; exec != nil && f.runid() == n.interp.runid(); {
+	for exec = n.exec; exec != nil && f.runid() == n.interp.runid(); {
 		exec = exec(f)
 	}
 }
@@ -343,6 +390,21 @@ func convert(n *node) {
 		return
 	}
 
+	if n.child[0].typ.cat == funcT && c.typ.cat == funcT {
+		value := genValue(c)
+		n.exec = func(f *frame) bltn {
+			n, ok := value(f).Interface().(*node)
+			if !ok || !n.typ.convertibleTo(c.typ) {
+				panic("cannot convert")
+			}
+			n1 := *n
+			n1.typ = c.typ
+			dest(f).Set(reflect.ValueOf(&n1))
+			return next
+		}
+		return
+	}
+
 	var value func(*frame) reflect.Value
 	if c.typ.cat == funcT {
 		value = genFunctionWrapper(c)
@@ -1719,6 +1781,11 @@ func neg(n *node) {
 			dest(f).SetInt(-value(f).Int())
 			return next
 		}
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		n.exec = func(f *frame) bltn {
+			dest(f).SetUint(-value(f).Uint())
+			return next
+		}
 	case reflect.Float32, reflect.Float64:
 		n.exec = func(f *frame) bltn {
 			dest(f).SetFloat(-value(f).Float())
@@ -2104,16 +2171,20 @@ func doComposite(n *node, hasType bool, keyed bool) {
 			val = c
 			fieldIndex = i
 		}
-		convertLiteralValue(val, typ.field[fieldIndex].typ.TypeOf())
+		ft := typ.field[fieldIndex].typ
+		rft := ft.TypeOf()
+		convertLiteralValue(val, rft)
 		switch {
+		case val.typ.cat == nilT:
+			values[fieldIndex] = func(*frame) reflect.Value { return reflect.New(rft).Elem() }
 		case val.typ.cat == funcT:
 			values[fieldIndex] = genFunctionWrapper(val)
 		case isArray(val.typ) && val.typ.val != nil && val.typ.val.cat == interfaceT:
 			values[fieldIndex] = genValueInterfaceArray(val)
-		case isRecursiveType(typ.field[fieldIndex].typ, typ.field[fieldIndex].typ.rtype):
-			values[fieldIndex] = genValueRecursiveInterface(val, typ.field[fieldIndex].typ.rtype)
-		case isInterface(typ.field[fieldIndex].typ):
-			values[fieldIndex] = genInterfaceWrapper(val, typ.field[fieldIndex].typ.rtype)
+		case isRecursiveType(ft, rft):
+			values[fieldIndex] = genValueRecursiveInterface(val, rft)
+		case isInterface(ft):
+			values[fieldIndex] = genInterfaceWrapper(val, rft)
 		default:
 			values[fieldIndex] = genValue(val)
 		}
@@ -3087,9 +3158,9 @@ func isNil(n *node) {
 		fnext := getExec(n.fnext)
 		if c0.typ.cat == interfaceT {
 			n.exec = func(f *frame) bltn {
-				vi := value(f).Interface().(valueInterface)
-				if (vi == valueInterface{} ||
-					vi.node.kind == basicLit && vi.node.typ.cat == nilT) {
+				v := value(f)
+				vi, ok := v.Interface().(valueInterface)
+				if ok && (vi == valueInterface{} || vi.node.kind == basicLit && vi.node.typ.cat == nilT) || v.IsNil() {
 					dest(f).SetBool(true)
 					return tnext
 				}
@@ -3109,7 +3180,12 @@ func isNil(n *node) {
 	} else {
 		if c0.typ.cat == interfaceT {
 			n.exec = func(f *frame) bltn {
-				dest(f).SetBool(value(f).Interface().(valueInterface) == valueInterface{})
+				v := value(f)
+				if vi, ok := v.Interface().(valueInterface); ok {
+					dest(f).SetBool(vi == valueInterface{} || vi.node.kind == basicLit && vi.node.typ.cat == nilT)
+				} else {
+					dest(f).SetBool(v.IsNil())
+				}
 				return tnext
 			}
 		} else {
@@ -3136,9 +3212,9 @@ func isNotNil(n *node) {
 		fnext := getExec(n.fnext)
 		if c0.typ.cat == interfaceT {
 			n.exec = func(f *frame) bltn {
-				vi := value(f).Interface().(valueInterface)
-				if (vi == valueInterface{} ||
-					vi.node.kind == basicLit && vi.node.typ.cat == nilT) {
+				v := value(f)
+				vi, ok := v.Interface().(valueInterface)
+				if ok && (vi == valueInterface{} || vi.node.kind == basicLit && vi.node.typ.cat == nilT) || v.IsNil() {
 					dest(f).SetBool(false)
 					return fnext
 				}
@@ -3158,7 +3234,12 @@ func isNotNil(n *node) {
 	} else {
 		if c0.typ.cat == interfaceT {
 			n.exec = func(f *frame) bltn {
-				dest(f).SetBool(!(value(f).Interface().(valueInterface) == valueInterface{}))
+				v := value(f)
+				if vi, ok := v.Interface().(valueInterface); ok {
+					dest(f).SetBool(!(vi == valueInterface{} || vi.node.kind == basicLit && vi.node.typ.cat == nilT))
+				} else {
+					dest(f).SetBool(!v.IsNil())
+				}
 				return tnext
 			}
 		} else {

interp/typecheck.go

@@ -217,6 +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--
@@ -226,6 +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)
 
@@ -241,16 +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
@@ -621,16 +634,13 @@ 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) {
+	if !n.typ.untyped || c == nil {
+		return nil
+	}
+	if isInterface(typ) || !isConstType(typ) {
 		typ = n.typ.defaultType()
 	}
-		if err := check.convertUntyped(n, typ); err != nil {
-			return err
-		}
-	}
-	return nil
+	return check.convertUntyped(n, typ)
 }
 
 type param struct {

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
 

stdlib/go1_15_crypto_des.go

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

stdlib/go1_15_crypto_dsa.go

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

stdlib/go1_15_crypto_ecdsa.go

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

stdlib/go1_15_crypto_ed25519.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/ed25519'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_elliptic.go

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

stdlib/go1_15_crypto_hmac.go

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

stdlib/go1_15_crypto_md5.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/md5'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_rand.go

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

stdlib/go1_15_crypto_rc4.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/rc4'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_rsa.go

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

stdlib/go1_15_crypto_sha1.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/sha1'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_sha256.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/sha256'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_sha512.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/sha512'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_subtle.go

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

stdlib/go1_15_crypto_tls.go

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

stdlib/go1_15_crypto_x509.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/x509'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_crypto_x509_pkix.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract crypto/x509/pkix'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_database_sql.go

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

stdlib/go1_15_database_sql_driver.go

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

stdlib/go1_15_debug_dwarf.go

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

stdlib/go1_15_debug_elf.go

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

stdlib/go1_15_debug_gosym.go

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

stdlib/go1_15_debug_macho.go

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

stdlib/go1_15_debug_pe.go

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

stdlib/go1_15_debug_plan9obj.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract debug/plan9obj'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_encoding.go

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

stdlib/go1_15_encoding_ascii85.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract encoding/ascii85'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_encoding_asn1.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract encoding/asn1'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_encoding_base32.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract encoding/base32'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_encoding_base64.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract encoding/base64'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_encoding_binary.go

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

stdlib/go1_15_encoding_csv.go

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

stdlib/go1_15_encoding_gob.go

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

stdlib/go1_15_encoding_hex.go

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

stdlib/go1_15_encoding_json.go

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

stdlib/go1_15_encoding_pem.go

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

stdlib/go1_15_encoding_xml.go

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

stdlib/go1_15_errors.go

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

stdlib/go1_15_expvar.go

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

stdlib/go1_15_flag.go

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

stdlib/go1_15_fmt.go

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

stdlib/go1_15_go_ast.go

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

stdlib/go1_15_go_build.go

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

stdlib/go1_15_go_constant.go

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

stdlib/go1_15_go_doc.go

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

stdlib/go1_15_go_format.go

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

stdlib/go1_15_go_importer.go

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

stdlib/go1_15_go_parser.go

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

stdlib/go1_15_go_printer.go

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

stdlib/go1_15_go_scanner.go

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

stdlib/go1_15_go_token.go

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

stdlib/go1_15_go_types.go

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

stdlib/go1_15_hash.go

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

stdlib/go1_15_hash_adler32.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract hash/adler32'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_hash_crc32.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract hash/crc32'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_hash_crc64.go

@@ -1,6 +1,6 @@
 // Code generated by 'yaegi extract hash/crc64'. DO NOT EDIT.
 
-// +build go1.15,!go1.16
+// +build go1.15
 
 package stdlib
 

stdlib/go1_15_hash_fnv.go

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

stdlib/go1_15_hash_maphash.go

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

stdlib/go1_15_html.go

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

stdlib/go1_15_html_template.go

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

stdlib/go1_15_image.go

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

stdlib/go1_15_image_color.go

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

stdlib/go1_15_image_color_palette.go

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

stdlib/go1_15_image_draw.go

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

stdlib/go1_15_image_gif.go

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

stdlib/go1_15_image_jpeg.go

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

stdlib/go1_15_image_png.go

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

stdlib/go1_15_index_suffixarray.go

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