New rule: prefer-true-attribute-shorthand

[g-plane]

Please describe what the rule should do:

In template, if there's an attribute whose value is true, such as :show="true", this rule will warn and provide auto fix (becomes show, see the example below). This can reduce verbosity.

What category should the rule belong to?

[x] Suggests an alternate way of doing something (suggestion)

Provide 2-3 code examples that this rule should warn about:

Invalid:

<template>
  <my-dialog :show="true" />
</template>

which can be fixed to:

<template>
  <my-dialog show />
</template>

[ota-meshi]

Thank you for rule proposal.
I would like to use that rule, but by the definition of props they are not equivalent.

<script>
export default {
  name: 'MyComponent',
  props: {
    a: Boolean,
    b: [String, Boolean]
  }
}
</script>

<template>
  <pre>
a: {{a}}
b: {{b}}
  </pre>
</template>

<template>
  <MyComponent a b/>
  <MyComponent :a="true" :b="true"/>
</template>

Output:

So far, I haven't found a way to distinguish them well. If you have a good idea, please let me know.

https://sfc.vuejs.org/#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

[ota-meshi]

If you change the order of types, both will give the same result.

<script>
export default {
  name: 'MyComponent',
  props: {
    a: Boolean,
-    b: [String, Boolean]
+    b: [Boolean, String]
  }
}
</script>

[FloEdelmann]

Duplicate of #775

[g-plane]

We still can report errors, but instead of providing auto fix, we can provide suggestions.

[ota-meshi]

instead of providing auto fix, we can provide suggestions.

Sounds good to me!