Better handle when trying to iterate on a `Range` of a type that isn't `Step`#151036

estebank · 2026-01-12T23:06:39Z

Mention when a trait bound corresponds to an unstable trait.

Mention Range when Step bound is unment, and explain that only some std types impl Iterator for Range.

rustbot · 2026-01-12T23:06:43Z

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rustbot · 2026-01-13T01:17:11Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

mati865

r=me with tests blessed

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estebank · 2026-01-13T16:57:06Z

tests/run-make/missing-unstable-trait-bound/missing-bound.stderr

+error[E0277]: `std::ops::Range<T>` is not an iterator
 --> missing-bound.rs:2:14
  |
 2 |     for _ in t {}
-  |              ^ the trait `Step` is not implemented for `T`
+  |              ^ not an iterator
  |
+  = note: `Range` only implements `Iterator` for select types in the standard library, particularly integers; to see the full list of types, see the documentation for the unstable `Step` trait
  = note: required for `std::ops::Range<T>` to implement `Iterator`
  = note: required for `std::ops::Range<T>` to implement `IntoIterator`


This tells me that we're missing a path for displaying the original label as a note, like we do in many other cases. Pre-existing.

estebank · 2026-01-13T16:57:48Z

tests/ui/range/range-1.stderr

-   |              ^^^^^^^^^^^ the trait `Step` is not implemented for `bool`
+   |              ^^^^^^^^^^^ not an iterator
   |
+   = help: the nightly-only, unstable trait `Step` is not implemented for `bool`


This is the note that I would have expected to see in the other case.

…ndancy

estebank · 2026-01-14T00:31:30Z

@bors r=mati865

rust-bors · 2026-01-14T00:31:33Z

📌 Commit 1fe705c has been approved by mati865

It is now in the queue for this repository.

Better handle when trying to iterate on a `Range` of a type that isn't `Step` Mention when a trait bound corresponds to an unstable trait. Mention `Range` when `Step` bound is unment, and explain that only some std types impl `Iterator` for `Range`. CC rust-lang#151026

@ghost

…uwer Rollup of 12 pull requests Successful merges: - #149408 (refactor: remove Ord bound from BinaryHeap::new etc) - #150406 (Change some `matches!(.., .. if ..)` with let-chains) - #150723 (std: move `errno` and related functions into `sys::io`) - #150877 (resolve: Refactor away the side table `decl_parent_modules`) - #150902 (Update to_uppercase docs to avoid ß->SS example) - #150962 (Remove `FeedConstTy` and provide ty when lowering const arg) - #151034 (std: Change UEFI env vars to volatile storage) - #151036 (Better handle when trying to iterate on a `Range` of a type that isn't `Step`) - #151067 (Avoid should-fail in two ui tests and a codegen-llvm test) - #151072 (also handle ENOTTY ioctl errors when checking pidfd -> pid support) - #151077 (Recognize potential `impl<const N: usize>` to `impl<N>` mistake) - #151096 (Remove `Deref`/`DerefMut` impl for `Providers`.) Failed merges: - #150939 (resolve: Relax some asserts in glob overwriting and add tests) r? @ghost

@ghost

…uwer Rollup of 11 pull requests Successful merges: - #149408 (refactor: remove Ord bound from BinaryHeap::new etc) - #150406 (Change some `matches!(.., .. if ..)` with let-chains) - #150723 (std: move `errno` and related functions into `sys::io`) - #150877 (resolve: Refactor away the side table `decl_parent_modules`) - #150902 (Update to_uppercase docs to avoid ß->SS example) - #151034 (std: Change UEFI env vars to volatile storage) - #151036 (Better handle when trying to iterate on a `Range` of a type that isn't `Step`) - #151067 (Avoid should-fail in two ui tests and a codegen-llvm test) - #151072 (also handle ENOTTY ioctl errors when checking pidfd -> pid support) - #151077 (Recognize potential `impl<const N: usize>` to `impl<N>` mistake) - #151096 (Remove `Deref`/`DerefMut` impl for `Providers`.) Failed merges: - #150939 (resolve: Relax some asserts in glob overwriting and add tests) r? @ghost

Rollup merge of #151036 - issue-151026, r=mati865 Better handle when trying to iterate on a `Range` of a type that isn't `Step` Mention when a trait bound corresponds to an unstable trait. Mention `Range` when `Step` bound is unment, and explain that only some std types impl `Iterator` for `Range`. CC #151026

@ghost

…uwer Rollup of 11 pull requests Successful merges: - rust-lang/rust#149408 (refactor: remove Ord bound from BinaryHeap::new etc) - rust-lang/rust#150406 (Change some `matches!(.., .. if ..)` with let-chains) - rust-lang/rust#150723 (std: move `errno` and related functions into `sys::io`) - rust-lang/rust#150877 (resolve: Refactor away the side table `decl_parent_modules`) - rust-lang/rust#150902 (Update to_uppercase docs to avoid ß->SS example) - rust-lang/rust#151034 (std: Change UEFI env vars to volatile storage) - rust-lang/rust#151036 (Better handle when trying to iterate on a `Range` of a type that isn't `Step`) - rust-lang/rust#151067 (Avoid should-fail in two ui tests and a codegen-llvm test) - rust-lang/rust#151072 (also handle ENOTTY ioctl errors when checking pidfd -> pid support) - rust-lang/rust#151077 (Recognize potential `impl<const N: usize>` to `impl<N>` mistake) - rust-lang/rust#151096 (Remove `Deref`/`DerefMut` impl for `Providers`.) Failed merges: - rust-lang/rust#150939 (resolve: Relax some asserts in glob overwriting and add tests) r? @ghost

Zalathar · 2026-02-16T04:08:11Z

I noticed that this PR has the side-effect of causing all compiler-internal traits to be reported as unstable, which is technically true but unhelpful when working on the compiler itself:

Trait-not-implemented diagnostics consider all compiler-internal traits to be unstable #152692

Suppress unstable-trait notes under `-Zforce-unstable-if-unmarked` - Fixes rust-lang#152692. --- rust-lang#151036 adds extra diagnostic text (“the nightly-only, unstable trait”) to note when a not-implemented trait is unstable. However, that extra text is usually unhelpful when building a crate graph with `-Zforce-unstable-if-unmarked` (such as the compiler or stdlib), because *any* trait not explicitly marked stable will be treated as unstable. (For typical compiler contributors using the stage0 compiler, this fix won't take effect until the next bootstrap beta bump.)

Rollup merge of #152698 - Zalathar:zforce, r=jieyouxu Suppress unstable-trait notes under `-Zforce-unstable-if-unmarked` - Fixes #152692. --- #151036 adds extra diagnostic text (“the nightly-only, unstable trait”) to note when a not-implemented trait is unstable. However, that extra text is usually unhelpful when building a crate graph with `-Zforce-unstable-if-unmarked` (such as the compiler or stdlib), because *any* trait not explicitly marked stable will be treated as unstable. (For typical compiler contributors using the stage0 compiler, this fix won't take effect until the next bootstrap beta bump.)

Suppress unstable-trait notes under `-Zforce-unstable-if-unmarked` - Fixes rust-lang/rust#152692. --- rust-lang/rust#151036 adds extra diagnostic text (“the nightly-only, unstable trait”) to note when a not-implemented trait is unstable. However, that extra text is usually unhelpful when building a crate graph with `-Zforce-unstable-if-unmarked` (such as the compiler or stdlib), because *any* trait not explicitly marked stable will be treated as unstable. (For typical compiler contributors using the stage0 compiler, this fix won't take effect until the next bootstrap beta bump.)

rustbot assigned mati865 Jan 12, 2026

estebank added 2 commits January 13, 2026 01:16

On unmet trait bound, mention if trait is unstable

cafe917

Mention Range when Step trait bound is unmet

89713fc

estebank force-pushed the issue-151026 branch from b377155 to 89713fc Compare January 13, 2026 01:17

Update rustc_on_unimplemented message for Step

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Update run-make test output

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rustbot added the A-run-make Area: port run-make Makefiles to rmake.rs label Jan 13, 2026

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Update main label

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mati865 approved these changes Jan 13, 2026

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Update ui-fulldeps --stage 2 tests

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estebank commented Jan 13, 2026

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estebank mentioned this pull request Jan 13, 2026

stable compiler should provide better advice for Step trait failures #151026

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Mention the type in the label, to avoid confusion at the cost of redu…

1fe705c

…ndancy

estebank force-pushed the issue-151026 branch from 5bd45b1 to 1fe705c Compare January 13, 2026 19:47

rust-bors bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jan 14, 2026

rust-bors bot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 14, 2026

JonathanBrouwer mentioned this pull request Jan 14, 2026

Rollup of 12 pull requests #151104

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JonathanBrouwer mentioned this pull request Jan 14, 2026

Rollup of 11 pull requests #151107

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rust-bors bot merged commit cbcd1c3 into rust-lang:main Jan 14, 2026
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rustbot added this to the 1.94.0 milestone Jan 14, 2026

github-actions bot mentioned this pull request Jan 28, 2026

Toolchain upgrade to nightly-2026-02-07 flux-rs/flux#1345

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Zalathar mentioned this pull request Feb 16, 2026

Trait-not-implemented diagnostics consider all compiler-internal traits to be unstable #152692

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Zalathar mentioned this pull request Feb 16, 2026

Suppress unstable-trait notes under -Zforce-unstable-if-unmarked #152698

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Better handle when trying to iterate on a `Range` of a type that isn't `Step`#151036