fix: add reflect.mapiterinit link for go1.18

resolve #6

map.go

@@ -54,21 +54,6 @@ type hiter struct {
 
 var zeroHiter = &hiter{}
 
-func newHiter(t, m unsafe.Pointer) *hiter {
-	v := hiterPool.Get()
-	if v == nil {
-		return newmapiter(t, m)
-	}
-	it := v.(*hiter)
-	*it = *zeroHiter
-	mapiterinit(t, m, unsafe.Pointer(it))
-	return it
-}
-
-//go:noescape
-//go:linkname newmapiter reflect.mapiterinit
-func newmapiter(unsafe.Pointer, unsafe.Pointer) *hiter
-
 //go:noescape
 //go:linkname mapiterinit runtime.mapiterinit
 func mapiterinit(unsafe.Pointer, unsafe.Pointer, unsafe.Pointer)

map_1.17.go

@@ -0,0 +1,20 @@
+// +build !go1.18
+
+package jettison
+
+import "unsafe"
+
+func newHiter(t, m unsafe.Pointer) *hiter {
+	v := hiterPool.Get()
+	if v == nil {
+		return newmapiter(t, m)
+	}
+	it := v.(*hiter)
+	*it = *zeroHiter
+	mapiterinit(t, m, unsafe.Pointer(it))
+	return it
+}
+
+//go:noescape
+//go:linkname newmapiter reflect.mapiterinit
+func newmapiter(unsafe.Pointer, unsafe.Pointer) *hiter

map_1.18.go

@@ -0,0 +1,22 @@
+// +build go1.18
+
+package jettison
+
+import "unsafe"
+
+func newHiter(t, m unsafe.Pointer) *hiter {
+	v := hiterPool.Get()
+	if v == nil {
+		var it hiter
+		newmapiter(t, m, &it)
+		return &it
+	}
+	it := v.(*hiter)
+	*it = *zeroHiter
+	mapiterinit(t, m, unsafe.Pointer(it))
+	return it
+}
+
+//go:noescape
+//go:linkname newmapiter reflect.mapiterinit
+func newmapiter(unsafe.Pointer, unsafe.Pointer, *hiter)