O'Reilly logo
  • Ivan Zderadicka thinks this is interesting:

The future will be computed once the main thread has some spare time, or when we call the block_on() function.

From

Cover of Rust High Performance

Note

This is not exact for this case - as future is not spawned there is no way for it to be calculated in some "spare" time. It'll be executed rather synchronously when block_on is called.