Discard is not taken into account in backpassing.

[KtorZ]

What Git revision are you using?

8495f98c1de050d51a6752e9645a5b955fd55195

What operating system are you using, and which version?

• [x] Linux / Ubuntu
• [x] Linux / Other
• [x] macOS
• [x] Windows

Describe what the problem is?

Things like:

let _ <- map(...)

raise an "unused variable" warning.

What should be the expected behavior?

This should be allowed and not trigger a warning.