fix: don't suggest .into_iter() for .cloned()/.copied() on non-reference Option by Albab-Hasan · Pull Request #157413 · rust-lang/rust

Albab-Hasan · 2026-06-04T05:29:51Z

calling .cloned() or .copied() on Option<T> where T is an owned type emitted "Option<T> is not an iterator" with a suggestion to prepend .into_iter(). the suggested code still did not compile: Option<T>::into_iter() yields T by value not &T so .cloned()/.copied() failed again for the same reason.

Option<T> implements IntoIterator which is why the impl_into_iterator_should_be_iterator branch fires. added a guard before it: when the method is cloned/copied, the receiver is Option<T> and T is a concrete non-reference type. emit a targeted label pointing at the correct form (Option<&T>) and suggest removing the call instead.

closes #151147

rustbot · 2026-06-04T05:29:56Z

r? @folkertdev

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folkertdev

Can you remove that link from the commit message (or just write it out fully as a https:// kind of link)

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folkertdev · 2026-06-07T20:44:14Z

+            && let ty::Adt(adt_def, args) = rcvr_ty.kind()
+            && tcx.is_diagnostic_item(sym::Option, adt_def.did())
+            && let inner_ty = args.type_at(0)
+            && !matches!(inner_ty.kind(), ty::Ref(..) | ty::Param(_) | ty::Infer(_))


Can you motivate this (and add a test that the correct error is emitted when the inner type is one of these)?

folkertdev · 2026-06-07T20:48:26Z

+            // The default branch below would suggest `.into_iter()`, but that still
+            // fails: `Option<T>` yields `T` by value, not `&T`, so `.cloned()`/`.copied()`
+            // can't resolve. Give a targeted diagnostic instead.
+            err.span_label(span, format!("this method is only available on `Option<&{inner_ty}>`"));


Suggested change

err.span_label(span, format!("this method is only available on `Option<&{inner_ty}>`"));

err.span_label(span, format!("this method is only available on `Option<&_>`"));

Maybe this should be Option<&_> instead, that is what the impl is actually for.

rustbot · 2026-06-07T20:49:09Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

…nce Option calling `.cloned()` or `.copied()` on `Option<T>` where `T` is an owned type emitted "`Option<T>` is not an iterator" with a suggestion to prepend `.into_iter()`. the suggested code still did not compile: `Option<T>::into_iter()` yields `T` by value not `&T`, so `.cloned()`/`.copied()` failed again for the same reason. `Option<T>` implements `IntoIterator`, which is why the `impl_into_iterator_should_be_iterator` branch fires. added a guard before it: when the method is `cloned`/`copied`, the receiver is `Option<T>`, and `T` is a concrete non-reference type, emit a targeted label pointing at the correct form (`Option<&T>`) and suggest removing the call instead.

Albab-Hasan · 2026-06-08T08:44:43Z

@rustbot ready

folkertdev · 2026-06-08T10:39:10Z

Thanks!

@bors r+ rollup

rust-bors · 2026-06-08T10:39:13Z

📌 Commit 4049f43 has been approved by folkertdev

It is now in the queue for this repository.

…diagnostic, r=folkertdev fix: don't suggest .into_iter() for .cloned()/.copied() on non-reference Option calling `.cloned()` or `.copied()` on `Option<T>` where `T` is an owned type emitted "`Option<T>` is not an iterator" with a suggestion to prepend `.into_iter()`. the suggested code still did not compile: `Option<T>::into_iter()` yields `T` by value not `&T` so `.cloned()`/`.copied()` failed again for the same reason. `Option<T>` implements `IntoIterator` which is why the `impl_into_iterator_should_be_iterator` branch fires. added a guard before it: when the method is `cloned`/`copied`, the receiver is `Option<T>` and `T` is a concrete non-reference type. emit a targeted label pointing at the correct form (`Option<&T>`) and suggest removing the call instead. closes rust-lang#151147

…uwer Rollup of 13 pull requests Successful merges: - #147302 (asm! support for the Xtensa architecture) - #148820 (Add very basic "comptime" fn implementation) - #157299 (Fix unstable diagnostics in tests) - #143511 (Improve TLS codegen by marking the panic/init path as cold) - #154608 (Add `_value` API for number literals in proc-macro) - #156762 (xfs support in `test_rename_directory_to_non_empty_directory`) - #157300 (Relax test requirements for consistency) - #157383 (tests: codegen-llvm: Ignore BPF targets in c-variadic-opt) - #157413 (fix: don't suggest .into_iter() for .cloned()/.copied() on non-reference Option) - #157578 (Fix diagnostics for non-exhaustive destructuring assignments (#157553)) - #157587 (explain that the size_of constant also serves to avoid optimizing away 'unused' size_of calls) - #157596 (test: remove ineffective link-extern-crate-with-drop-type test) - #157602 (rustdoc: Remove unnecessary fast path)

Rollup merge of #157413 - Albab-Hasan:option-cloned-non-ref-diagnostic, r=folkertdev fix: don't suggest .into_iter() for .cloned()/.copied() on non-reference Option calling `.cloned()` or `.copied()` on `Option<T>` where `T` is an owned type emitted "`Option<T>` is not an iterator" with a suggestion to prepend `.into_iter()`. the suggested code still did not compile: `Option<T>::into_iter()` yields `T` by value not `&T` so `.cloned()`/`.copied()` failed again for the same reason. `Option<T>` implements `IntoIterator` which is why the `impl_into_iterator_should_be_iterator` branch fires. added a guard before it: when the method is `cloned`/`copied`, the receiver is `Option<T>` and `T` is a concrete non-reference type. emit a targeted label pointing at the correct form (`Option<&T>`) and suggest removing the call instead. closes #151147

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 4, 2026

rustbot assigned folkertdev Jun 4, 2026

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jun 4, 2026

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Albab-Hasan force-pushed the option-cloned-non-ref-diagnostic branch from 5160827 to b394147 Compare June 4, 2026 06:02

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Albab-Hasan force-pushed the option-cloned-non-ref-diagnostic branch from b394147 to a49c252 Compare June 4, 2026 06:38

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Albab-Hasan force-pushed the option-cloned-non-ref-diagnostic branch from a49c252 to 914cc9c Compare June 4, 2026 09:00

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folkertdev requested changes Jun 7, 2026

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 7, 2026

Albab-Hasan force-pushed the option-cloned-non-ref-diagnostic branch from 914cc9c to 4049f43 Compare June 8, 2026 08:41

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 8, 2026

Albab-Hasan requested a review from folkertdev June 8, 2026 08:44

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 8, 2026

JonathanBrouwer mentioned this pull request Jun 8, 2026

Rollup of 9 pull requests #157610

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JonathanBrouwer mentioned this pull request Jun 8, 2026

Rollup of 13 pull requests #157616

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rust-bors Bot merged commit 4c561f2 into rust-lang:main Jun 8, 2026
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rustbot added this to the 1.98.0 milestone Jun 8, 2026

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fix: don't suggest .into_iter() for .cloned()/.copied() on non-reference Option#157413

fix: don't suggest .into_iter() for .cloned()/.copied() on non-reference Option#157413
rust-bors[bot] merged 1 commit into
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Albab-Hasan:option-cloned-non-ref-diagnostic

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	err.span_label(span, format!("this method is only available on `Option<&{inner_ty}>`"));
	err.span_label(span, format!("this method is only available on `Option<&_>`"));

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