fix:#6938 <keep-alive> should not cache anonymous components

[cuteyumiko]

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the dev branch for v2.x (or to a previous version branch), not the master branch
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

Other information:
anonymous components aslo have tag , so func getComponentName can not be used anymore.

[cuteyumiko]

@jkzing unit test added, please review

[dsonet]

why do you change the way of getting name? Plus doesn't need componentOptions && since it's already in the if branch.
IMO it should keep original logic opts.Ctor.options.name || opts.tag even if you want an optimization here which may not necessary

[cuteyumiko]

Thanks for review , already modified.

docs descripition:
The match is first checked on the component’s own name option, then its local registration name (the key in the parent’s components option) if the name option is not available. Anonymous components cannot be matched against.

Anonymous components always have a registered name( tag in code) , i think the descripition of docs may cause logical hole.

[jkzing]

@cuteyumiko IMO we may need to keep opts.tag. For example:

const foo = {
  template: `<div>foo</div>`
}

new Vue({
  el: '#app',
  components: {
    foo
  }
})

In above case, you'll find Ctor.options doesn't have a name property, but there actually is tag in it.

[cuteyumiko]

ehhh..i see
i have done another test for caching anonymous components , it turns out caching logic is ok

#6938 it's problem may be casued by vue-router , i tracked this issue in a wrong way

[PanJiaChen]

@cuteyumiko why close the pr ?

[cuteyumiko]

@PanJiaChen it works fine in offical unit test .your issue may be casued by vue-router .

[PanJiaChen]

may be is vue-router bug or vue. but the problem is objective existence.
if a router has not set name :

function getComponentName (opts) {
  return opts && (opts.Ctor.options.name || opts.tag)
}

this function will return undefined, so has some problems when use keep-alive
in

vue/src/core/components/keep-alive.js

Lines 88 to 94 in 1e14603

	const name: ?string = getComponentName(componentOptions)
	if (name && (
	(this.exclude && matches(this.exclude, name)) ||
	(this.include && !matches(this.include, name))
	)) {
	return vnode
	}

detail:#6938
@yyx990803