Version

16.0.0

Reproduction link

https://codepen.io/l1shu/pen/ExgwjbM

Steps to reproduce

In vue-loader@16

source code:

<template>
  <div />
</template>
<script>
export default {}
</script>

What is expected?

//
//
//
//
export default {}

What is actually happening?

export default {}

add param pad: 'line'
https://github.com/vuejs/vue-loader/blob/next/src/index.ts#L96

const { descriptor, errors } = parse(source, {
    filename,
    sourceMap,
    pad: 'line',
});

That's because the parser of @vue/compiler-sfc use pad=false as default.
see https://github.com/vuejs/vue-next/blob/master/packages/compiler-sfc/src/parse.ts#L84