apply disabled fix when inside a disabled fieldset (#202)

And if we are in a disabled fieldset, double check that we are not in
the first legend. Because in that case we are visually outside of the
fieldset and according to the spec those elements should **not** be
considered disabled.

Fixes: #194

packages/@headlessui-react/src/components/menu/menu.tsx

@@ -12,6 +12,7 @@ import { useId } from '../../hooks/use-id'
 import { Keys } from '../keyboard'
 import { Focus, calculateActiveIndex } from '../../utils/calculate-active-index'
 import { resolvePropValue } from '../../utils/resolve-prop-value'
+import { isDisabledReactIssue7711 } from '../../utils/bugs'
 
 enum MenuStates {
   Open,
@@ -413,7 +414,8 @@ function Item<TTag extends React.ElementType = typeof DEFAULT_ITEM_TAG>(
   }, [bag, id])
 
   const handleClick = React.useCallback(
-    (event: { preventDefault: Function }) => {
+    (event: React.MouseEvent) => {
+      if (isDisabledReactIssue7711(event.currentTarget)) return event.preventDefault()
       if (disabled) return event.preventDefault()
       dispatch({ type: ActionTypes.CloseMenu })
       disposables().nextFrame(() => state.buttonRef.current?.focus({ preventScroll: true }))

packages/@headlessui-react/src/components/switch/switch.tsx

@@ -5,6 +5,7 @@ import { render } from '../../utils/render'
 import { useId } from '../../hooks/use-id'
 import { Keys } from '../keyboard'
 import { resolvePropValue } from '../../utils/resolve-prop-value'
+import { isDisabledReactIssue7711 } from '../../utils/bugs'
 
 type StateDefinition = {
   switch: HTMLButtonElement | null
@@ -84,6 +85,7 @@ export function Switch<TTag extends React.ElementType = typeof DEFAULT_SWITCH_TA
   const toggle = React.useCallback(() => onChange(!checked), [onChange, checked])
   const handleClick = React.useCallback(
     (event: React.MouseEvent) => {
+      if (isDisabledReactIssue7711(event.currentTarget)) return event.preventDefault()
       event.preventDefault()
       toggle()
     },

packages/@headlessui-react/src/utils/bugs.ts

@@ -0,0 +1,30 @@
+// See: https://github.com/facebook/react/issues/7711
+// See: https://github.com/facebook/react/pull/20612
+// See: https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#concept-fe-disabled (2.)
+export function isDisabledReactIssue7711(element: Element): boolean {
+  let parent = element.parentElement
+  let legend = null
+
+  while (parent && !(parent instanceof HTMLFieldSetElement)) {
+    if (parent instanceof HTMLLegendElement) legend = parent
+    parent = parent.parentElement
+  }
+
+  let isParentDisabled = parent?.getAttribute('disabled') === '' ?? false
+  if (isParentDisabled && isFirstLegend(legend)) return false
+
+  return isParentDisabled
+}
+
+function isFirstLegend(element: HTMLLegendElement | null): boolean {
+  if (!element) return false
+
+  let previous = element.previousElementSibling
+
+  while (previous !== null) {
+    if (previous instanceof HTMLLegendElement) return false
+    previous = previous.previousElementSibling
+  }
+
+  return true
+}