reflect: use int in StringHeader and SliceHeader on non-AVR platforms (#4156)

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)
+}