fix(compiler-sfc): fix wrong scopeId for nested <script setup> components

packages/compiler-sfc/__tests__/compileScript.spec.ts

@@ -404,6 +404,32 @@ const myEmit = defineEmit(['foo', 'bar'])
       expect(content).toMatch(`ssrInterpolate`)
       assertCode(content)
     })
+
+    // _withId is only generated for backwards compat and is a noop when called
+    // in module scope.
+    // when inside setup(), currentInstance will be non-null and _withId will
+    // no longer be noop and cause scopeId errors.
+    // TODO: this test should no longer be necessary if we remove _withId
+    // codegen in 3.1
+    test('should not wrap render fn with withId when having scoped styles', async () => {
+      const { content } = compile(
+        `
+        <script setup>
+        const msg = 1
+        </script>
+        <template><h1>{{ msg }}</h1></template>
+        <style scoped>
+        h1 { color: red; }
+        </style>
+        `,
+        {
+          inlineTemplate: true
+        }
+      )
+      expect(content).toMatch(`return (_ctx, _cache`)
+      expect(content).not.toMatch(`_withId(`)
+      assertCode(content)
+    })
   })
 
   describe('with TypeScript', () => {