Inlining function with rest arguments leads to invalid code being generated

[jpdutoit]

Bug report

When inlining functions using rest arguments Terser sometimes tries to spread a rest argument into a variable, which is invalid Javascript. In the example below, it seems that Terser has missed that identity is only using its first argument.

Version (complete output of terser -V or specific git commit)

https://try.terser.org

Complete CLI command or minify() options used

{
  module: true,
  compress: {
    passes: 3
  }
}

terser input

function identity(x) {
  return x
}

function outer(keyFn) {
  return function inner(...args) {
    const key = keyFn(...args)
    console.log(key)
  }
}

outer(identity)(1)

terser output or error

!function(...o){const n=...o;console.log(n)}(1);

Expected result

!function(...o){const n=o[0];console.log(n)}(1);

or

!function(o){const n=o;console.log(n)}(1);

[fabiosantoscode]

Thanks for reporting! I think I know why this happened