Bad suggestion and false positive `redundant_iter_cloned`

Summary

After updating nightly rust today, I got a bad lint for the code at https://github.com/jj-vcs/jj/tree/a5b61b2cc331e8b8c7636b706ca1be9f1a33815b.

See https://github.com/jj-vcs/jj/pull/7557 for details (mostly copied below)

Lint Name

redundant_iter_cloned

Reproducer

I tried this code:

 let commits: std::collections::HashMap<CommitId, _> = bookmark_list_items
            .iter()
            .filter_map(|item| item.primary.target().added_ids().next())  // Iterator of type &CommitId
            .cloned()
            .map(|commit_id| {
                store
                    .get_commit(&commit_id)
                    .map(|commit| (commit_id, commit.store_commit().clone()))
            })
            .try_collect()?;

I saw this happen:

warning: unneeded cloning of iterator items
   --> cli/src/commands/bookmark/list.rs:251:19
    |
251 |           commits = bookmark_list_items
    |  ___________________^
252 | |             .iter()
253 | |             .filter_map(|item| item.primary.target().added_ids().next())
254 | |             .cloned()
...   |
258 | |                     .map(|commit| (commit_id, commit.store_commit().clone()))
259 | |             })
    | |______________^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_iter_cloned
    = note: `#[warn(clippy::redundant_iter_cloned)]` on by default
help: try
    |
253 ~             .filter_map(|item| item.primary.target().added_ids().next())
254 +             .map(|commit_id| {
255 +                 store
256 +                     .get_commit(&commit_id)
257 +                     .map(|commit| (commit_id, commit.store_commit().clone()))
258 +             })
    |

Following the suggestion and removing the .cloned() results in an error:

error[E0277]: a value of type `std::collections::HashMap<jj_lib::backend::CommitId, std::sync::Arc<jj_lib::backend::Commit>>` cannot be built from an iterator over elements of type `(&jj_lib::backend::CommitId, std::sync::Arc<jj_lib::backend::Commit>)`
    --> cli/src/commands/bookmark/list.rs:259:14
     |
 259 |             .try_collect()?;
     |              ^^^^^^^^^^^ value of type `std::collections::HashMap<jj_lib::backend::CommitId, std::sync::Arc<jj_lib::backend::Commit>>` cannot be built from `std::iter::Iterator<Item=(&jj_lib::backend::CommitId, std::sync::Arc<jj_lib::backend::Commit>)>`
     |
     = help: the trait `FromIterator<(&jj_lib::backend::CommitId, std::sync::Arc<_>)>` is not implemented for `std::collections::HashMap<jj_lib::backend::CommitId, std::sync::Arc<jj_lib::backend::Commit>>`
             but trait `FromIterator<(jj_lib::backend::CommitId, std::sync::Arc<_>)>` is implemented for it
     = help: for that trait implementation, expected `jj_lib::backend::CommitId`, found `&jj_lib::backend::CommitId`
     = note: required for `Result<HashMap<CommitId, Arc<Commit>>, BackendError>` to implement `FromIterator<Result<(&CommitId, Arc<Commit>), BackendError>>`
note: required by a bound in `itertools::Itertools::try_collect`
    --> /Users/ilyagr/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/itertools-0.14.0/src/lib.rs:2381:23
     |
2378 |     fn try_collect<T, U, E>(self) -> Result<U, E>
     |        ----------- required by a bound in this associated function
...
2381 |         Result<U, E>: FromIterator<Result<T, E>>,
     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Itertools::try_collect`
     = note: the full name for the type has been written to '/Users/ilyagr/dev/jj/target/debug/deps/jj_cli-442101cf9493e967.long-type-2991360816845051416.txt'
     = note: consider using `--verbose` to print the full type name to the console

The following diff satisfies clippy, but it doesn't seem much better than the original version, and certainly differs from what clippy suggested.

diff --git a/cli/src/commands/bookmark/list.rs b/cli/src/commands/bookmark/list.rs
index bd362dc9bf..bb9f26bc07 100644
--- a/cli/src/commands/bookmark/list.rs
+++ b/cli/src/commands/bookmark/list.rs
@@ -251,11 +251,10 @@
         commits = bookmark_list_items
             .iter()
             .filter_map(|item| item.primary.target().added_ids().next())
-            .cloned()
             .map(|commit_id| {
                 store
-                    .get_commit(&commit_id)
-                    .map(|commit| (commit_id, commit.store_commit().clone()))
+                    .get_commit(commit_id)
+                    .map(|commit| (commit_id.clone(), commit.store_commit().clone()))
             })
             .try_collect()?;
     }

Version

rustc 1.92.0-nightly (0be8e1608 2025-09-19)
binary: rustc
commit-hash: 0be8e16088894483a7012c5026c3247c14a0c3c2
commit-date: 2025-09-19
host: aarch64-apple-darwin
release: 1.92.0-nightly
LLVM version: 21.1.1

Additional Labels

I-suggestion-causes-error

No response

Reproduce the report with the Rust snippet and inspect the redundant_iter_cloned lint entry point. Compare its suggestion with cli/src/commands/bookmark/list.rs and verify that the suggested rewrite compiles while preserving the HashMap<CommitId, ...> collection. Done means the false positive and erroneous suggestion are covered and no longer occur.