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// To avoid leaking the names of local bindings from expressions like for loops, #60984
// explicitly ignored them, but an assertion that `LocalKind::Var` *must* have a name would
// trigger an ICE. Before this change, this file's output would be:
// ```
// error[E0515]: cannot return value referencing local variable `__next`
// --> return-local-binding-from-desugaring.rs:LL:CC
// |
// LL | for ref x in xs {
// | ----- `__next` is borrowed here
// ...
// LL | result
// | ^^^^^^ returns a value referencing data owned by the current function
// ```
// FIXME: ideally `LocalKind` would carry more information to more accurately explain the problem.
use std::collections::HashMap;
use std::hash::Hash;
fn group_by<I, F, T>(xs: &mut I, f: F) -> HashMap<T, Vec<&I::Item>>
where
I: Iterator,
F: Fn(&I::Item) -> T,
T: Eq + Hash,
{
let mut result = HashMap::new();
for ref x in xs {
let key = f(x);
result.entry(key).or_insert(Vec::new()).push(x);
}
result //~ ERROR cannot return value referencing temporary value
}
fn main() {}
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