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fix: type assertion of non-matching types

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This commit is contained in:
Nicholas Wiersma
2020-06-18 09:06:03 +02:00
committed by GitHub
parent 8365f687e7
commit 5cbbf9339c
3 changed files with 159 additions and 31 deletions
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104
interp/run.go
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@@ -125,6 +125,7 @@ func typeAssertStatus(n *node) {
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
rtype := c1.typ.rtype // type to assert
next := getExec(n.tnext)
switch {
@@ -136,24 +137,24 @@ func typeAssertStatus(n *node) {
return next
}
case isInterface(c1.typ):
rtype := c1.typ.rtype
n.exec = func(f *frame) bltn {
v := value(f)
value1(f).SetBool(v.IsValid() && v.Type().Implements(rtype))
ok := v.IsValid() && canAssertTypes(v.Elem().Type(), rtype)
value1(f).SetBool(ok)
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)
ok := v.IsValid() && canAssertTypes(v.Elem().Type(), rtype)
value1(f).SetBool(ok)
return next
}
default:
typID := c1.typ.id()
n.exec = func(f *frame) bltn {
v, ok := value(f).Interface().(valueInterface)
value1(f).SetBool(ok && v.node.typ.id() == typID)
ok = ok && v.value.IsValid() && canAssertTypes(v.value.Type(), rtype)
value1(f).SetBool(ok)
return next
}
}
@@ -162,7 +163,7 @@ func typeAssertStatus(n *node) {
func typeAssert(n *node) {
c0, c1 := n.child[0], n.child[1]
value := genValue(c0) // input value
dest := genValue(n) // returned result
value0 := genValue(n) // returned result
next := getExec(n.tnext)
switch {
@@ -178,34 +179,61 @@ func typeAssert(n *node) {
if !vi.node.typ.implements(typ) {
panic(n.cfgErrorf("interface conversion: %v is not %v", vi.node.typ.id(), typID))
}
dest(f).Set(v)
value0(f).Set(v)
return next
}
case isInterface(c1.typ):
rtype := n.child[1].typ.rtype
n.exec = func(f *frame) bltn {
dest(f).Set(value(f).Convert(rtype))
v := value(f).Elem()
typ := value0(f).Type()
if !v.IsValid() {
panic(fmt.Sprintf("interface conversion: interface {} is nil, not %s", typ.String()))
}
if !canAssertTypes(v.Type(), typ) {
method := firstMissingMethod(v.Type(), typ)
panic(fmt.Sprintf("interface conversion: %s is not %s: missing method %s", v.Type().String(), typ.String(), method))
}
value0(f).Set(v)
return next
}
case c0.typ.cat == valueT:
n.exec = func(f *frame) bltn {
dest(f).Set(value(f).Elem())
v := value(f).Elem()
typ := value0(f).Type()
if !v.IsValid() {
panic(fmt.Sprintf("interface conversion: interface {} is nil, not %s", typ.String()))
}
if !canAssertTypes(v.Type(), typ) {
method := firstMissingMethod(v.Type(), typ)
panic(fmt.Sprintf("interface conversion: %s is not %s: missing method %s", v.Type().String(), typ.String(), method))
}
value0(f).Set(v)
return next
}
default:
n.exec = func(f *frame) bltn {
dest(f).Set(value(f).Interface().(valueInterface).value)
v := value(f).Interface().(valueInterface)
typ := value0(f).Type()
if !v.value.IsValid() {
panic(fmt.Sprintf("interface conversion: interface {} is nil, not %s", typ.String()))
}
if !canAssertTypes(v.value.Type(), typ) {
panic(fmt.Sprintf("interface conversion: interface {} is %s, not %s", v.value.Type().String(), typ.String()))
}
value0(f).Set(v.value)
return next
}
}
}
func typeAssert2(n *node) {
value := genValue(n.child[0]) // input value
c0, c1 := n.child[0], n.child[1]
value := genValue(c0) // 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
typ := c1.typ // type to assert or convert to
typID := typ.id()
rtype := typ.rtype // type to assert
next := getExec(n.tnext)
switch {
@@ -221,27 +249,21 @@ func typeAssert2(n *node) {
return next
}
case isInterface(typ):
rtype := typ.rtype
n.exec = func(f *frame) bltn {
v := value(f)
ok := v.IsValid() && v.Type().Implements(rtype)
v := value(f).Elem()
ok := v.IsValid() && canAssertTypes(v.Type(), rtype)
if ok {
value0(f).Set(v.Convert(rtype))
value0(f).Set(v)
}
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()
v := value(f).Elem()
ok := v.IsValid() && canAssertTypes(v.Type(), rtype)
if ok {
if e := v.Elem(); e.Type() == rtype {
value0(f).Set(e)
} else {
ok = false
}
value0(f).Set(v)
}
value1(f).SetBool(ok)
return next
@@ -249,12 +271,9 @@ func typeAssert2(n *node) {
default:
n.exec = func(f *frame) bltn {
v, ok := value(f).Interface().(valueInterface)
ok = ok && v.value.IsValid() && canAssertTypes(v.value.Type(), rtype)
if ok {
if v.node.typ.id() == typID {
value0(f).Set(v.value)
} else {
ok = false
}
value0(f).Set(v.value)
}
value1(f).SetBool(ok)
return next
@@ -262,6 +281,29 @@ func typeAssert2(n *node) {
}
}
func canAssertTypes(src, dest reflect.Type) bool {
if src == dest {
return true
}
if dest.Kind() == reflect.Interface && src.Implements(dest) {
return true
}
if src.AssignableTo(dest) {
return true
}
return false
}
func firstMissingMethod(src, dest reflect.Type) string {
for i := 0; i < dest.NumMethod(); i++ {
m := dest.Method(i).Name
if _, ok := src.MethodByName(m); !ok {
return m
}
}
return ""
}
func convert(n *node) {
dest := genValue(n)
c := n.child[1]