make meta a function

Author: RobinMalfait

packages/@headlessui-react/src/hooks/document-overflow/handle-ios-locking.ts

@@ -15,8 +15,8 @@ export function handleIOSLocking(): ScrollLockStep<ContainerMetadata> {
   return {
     before({ doc, d, meta }) {
       function inAllowedContainer(el: Element) {
-        return meta.containers
-          .flatMap((resolve) => resolve())
+        return meta()
+          .containers.flatMap((resolve) => resolve())
           .some((container) => container.contains(el))
       }
 

packages/@headlessui-react/src/hooks/document-overflow/overflow-store.ts

@@ -24,7 +24,7 @@ export type MetaFn = (meta: Record<string, any>) => Record<string, any>
 export interface Context<MetaType extends Record<string, any> = any> {
   doc: Document
   d: Disposables
-  meta: MetaType
+  meta: () => MetaType
 }
 
 export interface ScrollLockStep<MetaType extends Record<string, any> = any> {
@@ -62,7 +62,17 @@ export let overflows = createStore(() => new Map<Document, DocEntry>(), {
     let ctx = {
       doc,
       d,
-      meta: buildMeta(meta),
+
+      // The moment we `PUSH`, we also `SCROLL_PREVENT`. But a later `PUSH` will
+      // not re-trigger a `SCROLL_PREVENT` because we are already in a locked
+      // state.
+      //
+      // This `meta()` function is called lazily such that a `PUSH` or `POP`
+      // that happens later can update the meta information. Otherwise we would
+      // use stale meta information.
+      meta() {
+        return buildMeta(meta)
+      },
     }
 
     let steps: ScrollLockStep<any>[] = [