internal/reflectlite, reflect: move StringHeader and SliceHeader back to package reflect

src/reflect/intw.go

@@ -0,0 +1,8 @@
+//go:build !avr
+
+package reflect
+
+// intw is an integer type, used in places where an int is typically required,
+// except architectures where the size of an int != word size.
+// See https://github.com/tinygo-org/tinygo/issues/1284.
+type intw = int

src/reflect/intw_avr.go

@@ -0,0 +1,8 @@
+//go:build avr
+
+package reflect
+
+// intw is an integer type, used in places where an int is typically required,
+// except architectures where the size of an int != word size.
+// See https://github.com/tinygo-org/tinygo/issues/1284.
+type intw = uintptr

src/reflect/intw_test.go

@@ -0,0 +1,30 @@
+//go:build !avr
+
+package reflect_test
+
+import (
+	"reflect"
+	"testing"
+	"unsafe"
+)
+
+// Verify that SliceHeader is the same size as a slice.
+var _ [unsafe.Sizeof([]byte{})]byte = [unsafe.Sizeof(reflect.SliceHeader{})]byte{}
+
+// TestSliceHeaderIntegerSize verifies that SliceHeader.Len and Cap are type int on non-AVR platforms.
+// See https://github.com/tinygo-org/tinygo/issues/1284.
+func TestSliceHeaderIntegerSize(t *testing.T) {
+	var h reflect.SliceHeader
+	h.Len = int(0)
+	h.Cap = int(0)
+}
+
+// Verify that StringHeader is the same size as a string.
+var _ [unsafe.Sizeof("hello")]byte = [unsafe.Sizeof(reflect.StringHeader{})]byte{}
+
+// TestStringHeaderIntegerSize verifies that StringHeader.Len and Cap are type int on non-AVR platforms.
+// See https://github.com/tinygo-org/tinygo/issues/1284.
+func TestStringHeaderIntegerSize(t *testing.T) {
+	var h reflect.StringHeader
+	h.Len = int(0)
+}

src/reflect/value.go

@@ -226,3 +226,24 @@ func (v Value) Recv() (x Value, ok bool) {
 func NewAt(typ Type, p unsafe.Pointer) Value {
 	panic("unimplemented: reflect.New()")
 }
+
+// Deprecated: Use unsafe.Slice or unsafe.SliceData instead.
+type SliceHeader struct {
+	Data uintptr
+	Len  intw
+	Cap  intw
+}
+
+// Deprecated: Use unsafe.String or unsafe.StringData instead.
+type StringHeader struct {
+	Data uintptr
+	Len  intw
+}
+
+// Verify SliceHeader and StringHeader sizes.
+// See https://github.com/tinygo-org/tinygo/pull/4156
+// and https://github.com/tinygo-org/tinygo/issues/1284.
+var (
+	_ [unsafe.Sizeof([]byte{})]byte = [unsafe.Sizeof(SliceHeader{})]byte{}
+	_ [unsafe.Sizeof("")]byte       = [unsafe.Sizeof(StringHeader{})]byte{}
+)