From 36918a907813f2ec7483981c444d914005598ab5 Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Thu, 2 Jun 2022 17:02:39 -0400
Subject: [PATCH] Flatten Fragments when rendering

---
 .../src/components/popover/popover.test.ts    | 44 +++++++++++++++++++
 packages/@headlessui-vue/src/utils/render.ts  | 31 ++++++++++++-
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/packages/@headlessui-vue/src/components/popover/popover.test.ts b/packages/@headlessui-vue/src/components/popover/popover.test.ts
index 54a730fe89..ac8a2c4a12 100644
--- a/packages/@headlessui-vue/src/components/popover/popover.test.ts
+++ b/packages/@headlessui-vue/src/components/popover/popover.test.ts
@@ -318,6 +318,50 @@ describe('Rendering', () => {
       })
     )
 
+    it(
+      'should be possible to render a PopoverButton with <slot> content',
+      suppressConsoleLogs(async () => {
+        renderTemplate({
+          template: html`<ExampleOuter><span>Some Content</span></ExampleOuter>`,
+          components: {
+            ExampleOuter: defineComponent({
+              template: html`<ExampleInner><slot /></ExampleInner>`,
+              components: {
+                ExampleInner: defineComponent({
+                  components: getDefaultComponents(),
+
+                  template: html`
+                    <Popover>
+                      <PopoverButton as="template">
+                        <slot />
+                      </PopoverButton>
+                      <PopoverPanel />
+                    </Popover>
+                  `,
+                }),
+              },
+            }),
+          },
+        })
+
+        assertPopoverButton({
+          state: PopoverState.InvisibleUnmounted,
+          attributes: { id: 'headlessui-popover-button-1' },
+          textContent: 'Some Content',
+        })
+        assertPopoverPanel({ state: PopoverState.InvisibleUnmounted })
+
+        await click(getPopoverButton())
+
+        assertPopoverButton({
+          state: PopoverState.Visible,
+          attributes: { id: 'headlessui-popover-button-1' },
+          textContent: 'Some Content',
+        })
+        assertPopoverPanel({ state: PopoverState.Visible })
+      })
+    )
+
     describe('`type` attribute', () => {
       it('should set the `type` to "button" by default', async () => {
         renderTemplate(
diff --git a/packages/@headlessui-vue/src/utils/render.ts b/packages/@headlessui-vue/src/utils/render.ts
index 10c742655b..172bd0d8ba 100644
--- a/packages/@headlessui-vue/src/utils/render.ts
+++ b/packages/@headlessui-vue/src/utils/render.ts
@@ -1,4 +1,4 @@
-import { h, cloneVNode, Slots } from 'vue'
+import { h, cloneVNode, Slots, Fragment, VNode } from 'vue'
 import { match } from './match'
 
 export enum Features {
@@ -102,6 +102,8 @@ function _render({
   }
 
   if (as === 'template') {
+    children = flattenFragments(children as VNode[])
+
     if (Object.keys(incomingProps).length > 0 || Object.keys(attrs).length > 0) {
       let [firstChild, ...other] = children ?? []
 
@@ -144,6 +146,33 @@ function _render({
   return h(as, Object.assign({}, incomingProps, dataAttributes), children)
 }
 
+/**
+ * When passed a structure like this:
+ * <Example><span>something</span></Example>
+ *
+ * And Example is defined as:
+ * <SomeComponent><slot /></SomeComponent>
+ *
+ * We need to turn the fragment that <slot> represents into the slot.
+ * Luckily by this point it's already rendered into an array of VNodes
+ * for us so we can just flatten it directly.
+ *
+ * We have to do this recursively because there could be multiple
+ * levels of Component nesting all with <slot> elements interspersed
+ *
+ * @param children
+ * @returns
+ */
+function flattenFragments(children: VNode[]): VNode[] {
+  return children.flatMap((child) => {
+    if (child.type === Fragment) {
+      return flattenFragments(child.children as VNode[])
+    }
+
+    return [child]
+  })
+}
+
 export function compact<T extends Record<any, any>>(object: T) {
   let clone = Object.assign({}, object)
   for (let key in clone) {