reflect: fix support for iter with named boolean in Seq/Seq2

Fixes #77542

Change-Id: Ic2f33f5aabbdf064cbf5aa850f6c08f01352db80
Reviewed-on: https://go-review.googlesource.com/c/go/+/745580
Auto-Submit: Alan Donovan <adonovan@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>

3 files changed, 23 insertions, 22 deletions

diff --git a/src/reflect/iter.go b/src/reflect/iter.go
index 03df87b178..b23c50a393 100644
--- a/src/reflect/iter.go
+++ b/src/reflect/iter.go
@@ -36,7 +36,7 @@ func rangeNum[T int8 | int16 | int32 | int64 | int |
 // Uint, Uint8, Uint16, Uint32, Uint64, Uintptr,
 // Array, Chan, Map, Slice, or String.
 func (v Value) Seq() iter.Seq[Value] {
-	if canRangeFunc(v.abiType()) {
+	if canRangeFunc(v.abiType(), 1) {
 		return func(yield func(Value) bool) {
 			rf := MakeFunc(v.Type().In(0), func(in []Value) []Value {
 				return []Value{ValueOf(yield(in[0]))}
@@ -122,7 +122,7 @@ func (v Value) Seq() iter.Seq[Value] {
 // If v's kind is Pointer, the pointer element type must have kind Array.
 // Otherwise v's kind must be Array, Map, Slice, or String.
 func (v Value) Seq2() iter.Seq2[Value, Value] {
-	if canRangeFunc2(v.abiType()) {
+	if canRangeFunc(v.abiType(), 2) {
 		return func(yield func(Value, Value) bool) {
 			rf := MakeFunc(v.Type().In(0), func(in []Value) []Value {
 				return []Value{ValueOf(yield(in[0], in[1]))}
diff --git a/src/reflect/iter_test.go b/src/reflect/iter_test.go
index 668d665280..164440f692 100644
--- a/src/reflect/iter_test.go
+++ b/src/reflect/iter_test.go
@@ -410,3 +410,20 @@ func (methodIter2) Seq2(yield func(int, int) bool) {
 
 // For Type.CanSeq2 test.
 func (methodIter2) NonSeq2(yield func(int, int)) {}
+
+func TestSeqRetNamedBool(t *testing.T) {
+	type Bool bool
+	// Note: Type.Name() == "bool" is a incorrect check,
+	// the named boolean type below will pass the incorrect check.
+	type bool Bool
+	v := ValueOf(func(func(int) bool) {})
+	if v.Type().CanSeq() {
+		t.Fatal("got true, want false")
+	}
+	shouldPanic("reflect: func(func(int) reflect_test.bool) cannot produce iter.Seq[Value]", func() { v.Seq() })
+	v2 := ValueOf(func(func(int, int) bool) {})
+	if v2.Type().CanSeq() {
+		t.Fatal("got true, want false")
+	}
+	shouldPanic("func(func(int, int) reflect_test.bool) cannot produce iter.Seq2[Value, Value]", func() { v2.Seq2() })
+}
diff --git a/src/reflect/type.go b/src/reflect/type.go
index cf22152ab2..c58bbaa26d 100644
--- a/src/reflect/type.go
+++ b/src/reflect/type.go
@@ -906,42 +906,26 @@ func (t *rtype) CanSeq() bool {
 	case Int8, Int16, Int32, Int64, Int, Uint8, Uint16, Uint32, Uint64, Uint, Uintptr, Array, Slice, Chan, String, Map:
 		return true
 	case Func:
-		return canRangeFunc(&t.t)
+		return canRangeFunc(&t.t, 1)
 	case Pointer:
 		return t.Elem().Kind() == Array
 	}
 	return false
 }
 
-func canRangeFunc(t *abi.Type) bool {
-	if t.Kind() != abi.Func {
-		return false
-	}
-	f := t.FuncType()
-	if f.InCount != 1 || f.OutCount != 0 {
-		return false
-	}
-	y := f.In(0)
-	if y.Kind() != abi.Func {
-		return false
-	}
-	yield := y.FuncType()
-	return yield.InCount == 1 && yield.OutCount == 1 && yield.Out(0).Kind() == abi.Bool
-}
-
 func (t *rtype) CanSeq2() bool {
 	switch t.Kind() {
 	case Array, Slice, String, Map:
 		return true
 	case Func:
-		return canRangeFunc2(&t.t)
+		return canRangeFunc(&t.t, 2)
 	case Pointer:
 		return t.Elem().Kind() == Array
 	}
 	return false
 }
 
-func canRangeFunc2(t *abi.Type) bool {
+func canRangeFunc(t *abi.Type, seq uint16) bool {
 	if t.Kind() != abi.Func {
 		return false
 	}
@@ -954,7 +938,7 @@ func canRangeFunc2(t *abi.Type) bool {
 		return false
 	}
 	yield := y.FuncType()
-	return yield.InCount == 2 && yield.OutCount == 1 && yield.Out(0).Kind() == abi.Bool
+	return yield.InCount == seq && yield.OutCount == 1 && yield.Out(0).Kind() == abi.Bool && toRType(yield.Out(0)).PkgPath() == ""
 }
 
 func (t *rtype) Fields() iter.Seq[StructField] {