Extending @vuepress/theme-default Layout.vue causes the Sidebar to disappear

[spiltcoffee]

• I confirm that this is a issue rather than a question.

Bug report

Version

vuepress 1.0.0-alpha.24

Steps to reproduce

1. Create a Layout that extends @vuepress/theme-default/layouts/Layout.vue

CustomLayout.vue

<script>
import Layout from "@vuepress/theme-default/layouts/Layout.vue";

export default {
  extends: Layout
}
</script>

2. Use Layout

index.md

---
layout: CustomLayout
---

What is expected?

Default layout to appear as expected

What is actually happening?

The sidebar is always hidden.

I believe this is to do with the following function:

vuepress/packages/@vuepress/theme-default/layouts/Layout.vue

Lines 93 to 101 in ace3aec

	shouldShowSidebar () {
	const { frontmatter } = this.$page
	return (
	!frontmatter.layout &&
	!frontmatter.home &&
	frontmatter.sidebar !== false &&
	this.sidebarItems.length
	)
	},

Checking for !frontmatter.layout causes the sidebar to always be hidden if you inherit the default Layout.vue in this way.

It's possible to get around the issue by redefining shouldShowSidebar() in the inherited component, but I'm wondering whether there should even be a check for !frontmatter.layout anyway, seeing as LayoutDistributor.vue will replace the whole component if frontmatter.layout is defined.

Other relevant information

• Your OS: Windows 10
• Node.js version: 10.6.0
• Browser version: Chrome 70
• Is this a global or local install? local
• Which package manager did you use for the install? npm 6.4.0

[ulivz]

Fixed at 8dd418e