fix: func reflect impl for named functions, updated tests

Co-authored-by: Ethan Lewis <[email protected]>

src/reflect/all_test.go

@@ -3312,6 +3312,8 @@ func TestMethodPkgPath(t *testing.T) {
 	}
 }
 
+*/
+
 func TestVariadicType(t *testing.T) {
 	// Test example from Type documentation.
 	var f func(x int, y ...float64)
@@ -3335,6 +3337,8 @@ func TestVariadicType(t *testing.T) {
 	t.Error(s)
 }
 
+/*
+
 type inner struct {
 	x int
 }

src/reflect/type.go

@@ -608,14 +608,22 @@ func (t *rawType) String() string {
 		s += " }"
 		return s
 	case Func:
+		isVariadic := t.IsVariadic()
 
 		f := "func("
 		for i := 0; i < t.NumIn(); i++ {
 			if i > 0 {
 				f += ", "
 			}
-			f += t.In(i).String()
+
+			input := t.In(i).String()
+			if isVariadic && i == t.NumIn()-1 {
+				f += "..."
+				input = input[2:]
+			}
+			f += input
 		}
+
 		f += ") "
 
 		var rets string
@@ -1069,21 +1077,36 @@ func (t *rawType) ConvertibleTo(u Type) bool {
 }
 
 func (t *rawType) IsVariadic() bool {
-	// need to test if bool mapped to int set by compiler
+	if t.isNamed() {
+		named := (*namedType)(unsafe.Pointer(t))
+		t = named.elem
+	}
+
 	if t.Kind() != Func {
 		panic("reflect: IsVariadic of non-func type")
 	}
+
 	return (*funcType)(unsafe.Pointer(t)).variadic
 }
 
 func (t *rawType) NumIn() int {
+	if t.isNamed() {
+		named := (*namedType)(unsafe.Pointer(t))
+		return int((*funcType)(unsafe.Pointer(named.elem)).inCount)
+	}
+
 	if t.Kind() != Func {
 		panic("reflect: NumIn of non-func type")
 	}
 	return int((*funcType)(unsafe.Pointer(t)).inCount)
 }
 
 func (t *rawType) NumOut() int {
+	if t.isNamed() {
+		named := (*namedType)(unsafe.Pointer(t))
+		return int((*funcType)(unsafe.Pointer(named.elem)).outCount)
+	}
+
 	if t.Kind() != Func {
 		panic("reflect: NumOut of non-func type")
 	}
@@ -1163,33 +1186,43 @@ func addChecked(p unsafe.Pointer, x uintptr, whySafe string) unsafe.Pointer {
 }
 
 func (t *rawType) In(i int) Type {
+	if t.isNamed() {
+		named := (*namedType)(unsafe.Pointer(t))
+		t = named.elem
+	}
+
 	if t.Kind() != Func {
 		panic(errTypeField)
 	}
-	descriptor := (*funcType)(unsafe.Pointer(t.underlying()))
-	if uint(i) >= uint(descriptor.inCount) {
+	fType := (*funcType)(unsafe.Pointer(t))
+	if uint(i) >= uint(fType.inCount) {
 		panic("reflect: field index out of range")
 	}
 
-	pointer := (unsafe.Add(unsafe.Pointer(&descriptor.fields[0]), uintptr(i)*unsafe.Sizeof(unsafe.Pointer(nil))))
-	return (*rawType)(*(**rawType)(pointer))
+	pointer := (unsafe.Add(unsafe.Pointer(&fType.fields[0]), uintptr(i)*unsafe.Sizeof(unsafe.Pointer(nil))))
+	return (*(**rawType)(pointer))
 }
 
 func (t *rawType) Out(i int) Type {
+	if t.isNamed() {
+		named := (*namedType)(unsafe.Pointer(t))
+		t = named.elem
+	}
+
 	if t.Kind() != Func {
 		panic(errTypeField)
 	}
 
-	descriptor := (*funcType)(unsafe.Pointer(t.underlying()))
-	if uint(i) >= uint(descriptor.outCount) {
+	fType := (*funcType)(unsafe.Pointer(t))
+
+	if uint(i) >= uint(fType.outCount) {
 		panic("reflect: field index out of range")
 	}
 
 	// Shift the index by the number of input parameters.
-	i = i + int((*funcType)(unsafe.Pointer(t)).inCount)
-
-	pointer := (unsafe.Add(unsafe.Pointer(&descriptor.fields[0]), uintptr(i)*unsafe.Sizeof(unsafe.Pointer(nil))))
-	return (*rawType)(*(**rawType)(pointer))
+	i = i + int(fType.inCount)
+	pointer := (unsafe.Add(unsafe.Pointer(&fType.fields[0]), uintptr(i)*unsafe.Sizeof(unsafe.Pointer(nil))))
+	return (*(**rawType)(pointer))
 }
 
 // OverflowComplex reports whether the complex128 x cannot be represented by type t.

src/reflect/type_test.go

@@ -13,6 +13,7 @@ func TestTypeFor(t *testing.T) {
 	type (
 		mystring string
 		myiface  interface{}
+		myfunc   func()
 	)
 
 	testcases := []struct {
@@ -25,6 +26,7 @@ func TestTypeFor(t *testing.T) {
 		{new(mystring), reflect.TypeFor[mystring]()},
 		{new(any), reflect.TypeFor[any]()},
 		{new(myiface), reflect.TypeFor[myiface]()},
+		{new(myfunc), reflect.TypeFor[myfunc]()},
 	}
 	for _, tc := range testcases {
 		want := reflect.ValueOf(tc.wantFrom).Elem().Type()

src/reflect/value_test.go

@@ -487,6 +487,59 @@ func TestTinyStruct(t *testing.T) {
 	}
 }
 
+func TestTinyFunc(t *testing.T) {
+	type barStruct struct {
+		QuxString string
+		BazInt    int
+	}
+
+	type foobar func(bar barStruct, x int, v ...string) string
+
+	var fb foobar
+
+	reffb := TypeOf(fb)
+
+	numIn := reffb.NumIn()
+	if want := 3; numIn != want {
+		t.Errorf("NumIn=%v, want %v", numIn, want)
+	}
+
+	numOut := reffb.NumOut()
+	if want := 1; numOut != want {
+		t.Errorf("NumOut=%v, want %v", numOut, want)
+	}
+
+	in0 := reffb.In(0)
+	if want := TypeOf(barStruct{}); in0 != want {
+		t.Errorf("In(0)=%v, want %v", in0, want)
+	}
+
+	in1 := reffb.In(1)
+	if want := TypeOf(0); in1 != want {
+		t.Errorf("In(1)=%v, want %v", in1, want)
+	}
+
+	in2 := reffb.In(2)
+	if want := TypeOf([]string{}); in2 != want {
+		t.Errorf("In(2)=%v, want %v", in2, want)
+	}
+
+	out0 := reffb.Out(0)
+	if want := TypeOf(""); out0 != want {
+		t.Errorf("Out(0)=%v, want %v", out0, want)
+	}
+
+	isVariadic := reffb.IsVariadic()
+	if want := true; isVariadic != want {
+		t.Errorf("IsVariadic=%v, want %v", isVariadic, want)
+	}
+
+	if got, want := reffb.String(), "reflect_test.foobar"; got != want {
+		t.Errorf("Value.String()=%v, want %v", got, want)
+	}
+
+}
+
 func TestTinyZero(t *testing.T) {
 	s := "hello, world"
 	sptr := &s