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fix: finish support of type assertions which was incomplete (#657)

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* fix: finish support of type assertions which was incomplete

TypeAssert was optimistically returning ok without verifying that
value could be converted to the required interface (in case of
type assert of an interface type), or not checking the type in
all conditions. There is now a working implements method for itype.

Fixes #640.

* style: appease lint

* fix: remove useless code block

* doc: improve comments

* avoid test conflict
This commit is contained in:
Marc Vertes
2020-06-10 11:21:16 +02:00
committed by GitHub
parent def57d57c2
commit c1f5005b2a
5 changed files with 176 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
_test/method33.go Normal file
View File

@@ -0,0 +1,58 @@
package main
import (
"fmt"
)
type T1 struct{}
func (t1 T1) f() {
fmt.Println("T1.f()")
}
func (t1 T1) g() {
fmt.Println("T1.g()")
}
type T2 struct {
T1
}
func (t2 T2) f() {
fmt.Println("T2.f()")
}
type I interface {
f()
}
func printType(i I) {
if t1, ok := i.(T1); ok {
println("T1 ok")
t1.f()
t1.g()
}
if t2, ok := i.(T2); ok {
println("T2 ok")
t2.f()
t2.g()
}
}
func main() {
println("T1")
printType(T1{})
println("T2")
printType(T2{})
}
// Output:
// T1
// T1 ok
// T1.f()
// T1.g()
// T2
// T2 ok
// T2.f()
// T1.g()

23
_test/method34.go Normal file
View File

@@ -0,0 +1,23 @@
package main
type Root struct {
Name string
}
type One struct {
Root
}
type Hi interface {
Hello() string
}
func (r *Root) Hello() string { return "Hello " + r.Name }
func main() {
var one interface{} = &One{Root{Name: "test2"}}
println(one.(Hi).Hello())
}
// Output:
// Hello test2

1
interp/gta.go
View File

@@ -137,6 +137,7 @@ func (interp *Interpreter) gta(root *node, rpath, pkgID string) ([]*node, error)
}
}
rcvrtype.method = append(rcvrtype.method, n)
n.child[0].child[0].lastChild().typ = rcvrtype
} else {
// Add a function symbol in the package name space
sc.sym[n.child[1].ident] = &symbol{kind: funcSym, typ: n.typ, node: n, index: -1}

115
interp/run.go
View File

@@ -122,34 +122,38 @@ func runCfg(n *node, f *frame) {
}
func typeAssertStatus(n *node) {
c0, c1 := n.child[0], n.child[1]
c0, c1 := n.child[0], n.child[1] // cO contains the input value, c1 the type to assert
value := genValue(c0) // input value
value1 := genValue(n.anc.child[1]) // returned status
typ := c1.typ.rtype // type to assert
next := getExec(n.tnext)
switch {
case c0.typ.cat == valueT:
case isInterfaceSrc(c1.typ):
typ := c1.typ
n.exec = func(f *frame) bltn {
v := value(f)
if !v.IsValid() || v.IsNil() {
value1(f).SetBool(false)
}
value1(f).SetBool(v.Type().Implements(typ))
v, ok := value(f).Interface().(valueInterface)
value1(f).SetBool(ok && v.node.typ.implements(typ))
return next
}
case c1.typ.cat == interfaceT:
case isInterface(c1.typ):
rtype := c1.typ.rtype
n.exec = func(f *frame) bltn {
_, ok := value(f).Interface().(valueInterface)
// TODO: verify that value(f) implements asserted type.
value1(f).SetBool(ok)
v := value(f)
value1(f).SetBool(v.IsValid() && v.Type().Implements(rtype))
return next
}
case c0.typ.cat == valueT:
rtype := c1.typ.rtype
n.exec = func(f *frame) bltn {
v := value(f)
value1(f).SetBool(v.IsValid() && v.Type() == rtype)
return next
}
default:
typID := c1.typ.id()
n.exec = func(f *frame) bltn {
_, ok := value(f).Interface().(valueInterface)
// TODO: verify that value(f) implements asserted type.
value1(f).SetBool(ok)
v, ok := value(f).Interface().(valueInterface)
value1(f).SetBool(ok && v.node.typ.id() == typID)
return next
}
}
@@ -162,24 +166,35 @@ func typeAssert(n *node) {
next := getExec(n.tnext)
switch {
case c0.typ.cat == valueT:
case isInterfaceSrc(c1.typ):
typ := n.child[1].typ
typID := n.child[1].typ.id()
n.exec = func(f *frame) bltn {
v := value(f)
dest(f).Set(v.Elem())
vi, ok := v.Interface().(valueInterface)
if !ok {
panic(n.cfgErrorf("interface conversion: nil is not %v", typID))
}
if !vi.node.typ.implements(typ) {
panic(n.cfgErrorf("interface conversion: %v is not %v", vi.node.typ.id(), typID))
}
dest(f).Set(v)
return next
}
case c1.typ.cat == interfaceT:
case isInterface(c1.typ):
rtype := n.child[1].typ.rtype
n.exec = func(f *frame) bltn {
v := value(f).Interface().(valueInterface)
// TODO: verify that value(f) implements asserted type.
dest(f).Set(reflect.ValueOf(valueInterface{v.node, v.value}))
dest(f).Set(value(f).Convert(rtype))
return next
}
case c0.typ.cat == valueT:
n.exec = func(f *frame) bltn {
dest(f).Set(value(f).Elem())
return next
}
default:
n.exec = func(f *frame) bltn {
v := value(f).Interface().(valueInterface)
// TODO: verify that value(f) implements asserted type.
dest(f).Set(v.value)
dest(f).Set(value(f).Interface().(valueInterface).value)
return next
}
}
@@ -189,30 +204,58 @@ func typeAssert2(n *node) {
value := genValue(n.child[0]) // input value
value0 := genValue(n.anc.child[0]) // returned result
value1 := genValue(n.anc.child[1]) // returned status
typ := n.child[1].typ // type to assert or convert to
typID := typ.id()
next := getExec(n.tnext)
switch {
case n.child[0].typ.cat == valueT:
n.exec = func(f *frame) bltn {
if value(f).IsValid() && !value(f).IsNil() {
value0(f).Set(value(f).Elem())
}
value1(f).SetBool(true)
return next
}
case n.child[1].typ.cat == interfaceT:
case isInterfaceSrc(typ):
n.exec = func(f *frame) bltn {
v, ok := value(f).Interface().(valueInterface)
// TODO: verify that value(f) implements asserted type.
value0(f).Set(reflect.ValueOf(valueInterface{v.node, v.value}))
if ok && v.node.typ.id() == typID {
value0(f).Set(value(f))
} else {
ok = false
}
value1(f).SetBool(ok)
return next
}
case isInterface(typ):
rtype := typ.rtype
n.exec = func(f *frame) bltn {
v := value(f)
ok := v.IsValid() && v.Type().Implements(rtype)
if ok {
value0(f).Set(v.Convert(rtype))
}
value1(f).SetBool(ok)
return next
}
case n.child[0].typ.cat == valueT:
rtype := n.child[1].typ.rtype
n.exec = func(f *frame) bltn {
v := value(f)
ok := v.IsValid() && !value(f).IsNil()
if ok {
if e := v.Elem(); e.Type() == rtype {
value0(f).Set(e)
} else {
ok = false
}
}
value1(f).SetBool(ok)
return next
}
default:
n.exec = func(f *frame) bltn {
v, ok := value(f).Interface().(valueInterface)
// TODO: verify that value(f) implements asserted type.
if ok {
if v.node.typ.id() == typID {
value0(f).Set(v.value)
} else {
ok = false
}
}
value1(f).SetBool(ok)
return next
}

22
interp/type.go
View File

@@ -818,7 +818,7 @@ func (t *itype) methods() methodSet {
res := make(methodSet)
switch t.cat {
case interfaceT:
// Get methods from recursive analysis of interface fields
// Get methods from recursive analysis of interface fields.
for _, f := range t.field {
if f.typ.cat == funcT {
res[f.name] = f.typ.TypeOf().String()
@@ -829,23 +829,26 @@ func (t *itype) methods() methodSet {
}
}
case valueT, errorT:
// Get method from corresponding reflect.Type
// Get method from corresponding reflect.Type.
for i := t.rtype.NumMethod() - 1; i >= 0; i-- {
m := t.rtype.Method(i)
res[m.Name] = m.Type.String()
}
case ptrT:
// Consider only methods where receiver is a pointer to type t
for _, m := range t.val.method {
if m.child[0].child[0].lastChild().typ.cat == ptrT {
res[m.ident] = m.typ.TypeOf().String()
for k, v := range t.val.methods() {
res[k] = v
}
case structT:
for _, f := range t.field {
for k, v := range f.typ.methods() {
res[k] = v
}
}
default:
}
// Get all methods defined on this type.
for _, m := range t.method {
res[m.ident] = m.typ.TypeOf().String()
}
}
return res
}
@@ -1192,8 +1195,7 @@ func (t *itype) implements(it *itype) bool {
if t.cat == valueT {
return t.TypeOf().Implements(it.TypeOf())
}
// TODO: implement method check for interpreted types
return true
return t.methods().contains(it.methods())
}
func defRecvType(n *node) *itype {