error[E0593]: closure is expected to take a single 2-tuple as argument, but it takes 2 distinct arguments
  --> $DIR/closure-arg-count-expected-type-issue-47244.rs:16:23
   |
LL |     let _n = m.iter().map(|_, b| {
   |                       ^^^ ------ takes 2 distinct arguments
   |                       |
   |                       expected closure that takes a single 2-tuple as argument
   |
help: change the closure to accept a tuple instead of individual arguments
   |
LL |     let _n = m.iter().map(|(_, b)| {
   |                           ~~~~~~~~

error: aborting due to previous error

For more information about this error, try `rustc --explain E0593`.