test(runtime-core): incomplete type inferred by generic components

Added test to ensure that `script setup` with a generic argument
_and_ runtime declarations returns the correct type, and verified
that the test does _not_ pass without the patch.

Author: pfumagalli

packages/dts-test/setupHelpers.test-d.ts

@@ -4,6 +4,7 @@ import {
   useAttrs,
   useSlots,
   withDefaults,
+  PropType,
   Slots,
   defineSlots,
   VNode,
@@ -193,6 +194,26 @@ describe('defineProps w/ runtime declaration', () => {
   props2.baz
 })
 
+describe('defineProps w/ generics and runtime declarations', () => {
+  function test<T extends Record<string, any>>() {
+    const props = defineProps({
+      foo: {
+        type: Object as PropType<T>,
+        required: false,
+        default: null,
+      },
+      bar: {
+        type: Object as PropType<T>,
+        required: true,
+      },
+    })
+    expectType<T | null>(props.foo)
+    expectType<T>(props.bar)
+  }
+  test()
+})
+
+
 describe('defineEmits w/ type declaration', () => {
   const emit = defineEmits<(e: 'change') => void>()
   emit('change')