Macro polonius

macro_rules! polonius {
    (
    |$var:ident $(,)?| -> $Ret:ty
        $body:block
    $(,)?
) => { ... };
}

Convenient entry-point to this crate’s logic.

• See the top-level docs for more info.

Usage

• use ::polonius_the_crab::prelude::*;
  
  let mut a_mut_binding: &mut _ = // …
  
  //                                      the lifetime placeholder has to be
  //                                          named `'polonius` !!
  //                                               vvvvvvvvv
  let x = polonius!(|a_mut_binding| -> SomeRetType<'polonius> {
      let some_dependent_type = stuff(a_mut_binding);
      if some_cond() {
          polonius_return!(some_dependent_type);
      }
      if some_other_cond() {
          exit_polonius!(42);
          unreachable!();
      }
      42
  });
  assert_eq!(x, 42);
  stuff(a_mut_binding) // macro gave it back
  // …

Generic parameters

They Just Work™.

• use ::polonius_the_crab::prelude::*;
  
  fn get_or_insert<'map, 'v, K, V : ?Sized> (
      mut map: &'map mut ::std::collections::HashMap<K, &'v V>,
      key: &'_ K,
      fallback_value: &'v V,
  ) -> &'map &'v V
  where
      K : ::core::hash::Hash + Eq + Clone,
      V : ::core::fmt::Debug,
  {
      polonius!(|map| -> &'polonius &'v V {
          if let Some(v) = map.get(key) {
              dbg!(v);
              polonius_return!(v);
          }
      });
      map.insert(key.clone(), fallback_value);
      &map[key]
  }