I was pondering upon the old "dynamic keys" extraction problem recently and I had an idea that I think might work, but I have nowhere near enough knowledge or experience with either TS API or Babel plugins to be sure, so I'll just put this up here and perhaps someone can shed more light on it.

It is clear why extracting entirely dynamic keys as in

const key: string = 'foo';

intl.formatMessage({
  id: `message.${key}`
})

// or
intl.formatMessage({
  id: key
})

cannot work. However, if we are very strict about the type of key - which in my experience is often the case, and most of the time can be achieved in a healthy codebase - I think perhaps the extractor could actually infer all possible variations? E.g.

const key1: 'foo' | 'bar';
const key2: 'baz' | 'qux';

intl.formatMessage({
  id: `message.${key1}.prop.${key2}` as const
})

could actually generate all of

"message.foo.prop.baz",
"message.foo.prop.qux",
"message.bar.prop.baz",
"message.bar.prop.qux"

If this were possible, I think it may solve many, if not most of the existing "I want to extract dynamic keys" problems, at least for strict Typescript users. In the codebase I work on, this is actually 100% of cases with interpolated message IDs.