do not complain about unstable target features on nightly by RalfJung · Pull Request #163428 · rust-lang/rust

RalfJung · 2026-09-28T08:34:30Z

This was brought up in #162235 (comment): we currently print a warning on nightly saying that using an unstable target feature will become a hard error. That's a mistake.

We could either remove the part of the warning that talks about it becoming a hard error, or we could just hide the warning entirely for unstable features on nighty. I went for the latter -- nightly is meant for experimentation with those features so having un-silenceable warnings is not great.

Cc @workingjubilee

rustbot · 2026-09-28T08:34:33Z

The rustc-dev-guide subtree was changed. If your future PRs only touch the subtree, consider submitting them directly to rust-lang/rustc-dev-guide, which is where the document is primarily maintained (and has faster CI).

cc @BoxyUwU, @tshepang

rustbot · 2026-09-28T08:34:36Z

r? @petrochenkov

rustbot has assigned @petrochenkov.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: compiler
compiler expanded to 77 candidates
Random selection from 19 candidates

RalfJung · 2026-09-28T08:35:10Z

 //@ rustc-env:RUSTC_BOOTSTRAP=1
-
-// Or force nightly rustc to pretend it is a stable rustc
-//@ rustc-env:RUSTC_BOOTSTRAP=-1


I don't know if rustc-env:RUSTC_BOOTSTRAP=1 ever makes sense in a ui test, but rustc-env:RUSTC_BOOTSTRAP=-1 definitely does not.
Cc @jieyouxu

View changes since the review

Yeah... This is #t-compiler > Testing stable vs nightly behavior in UI tests

Okay so rustc-env:RUSTC_BOOTSTRAP=1 is also pointless. I'll remove the example then.

petrochenkov · 2026-09-28T15:04:36Z

r=me after fixing tidy.
@rustbot author

RalfJung · 2026-09-28T15:36:37Z

Lol, tidy +rustfmt make it impossible to have an empty file. I guess I'm going to have to add a dummy function.

RalfJung · 2026-09-28T15:40:24Z

@bors r=petrochenkov rollup

rust-bors · 2026-09-28T15:40:28Z

📌 Commit edc2f3b has been tentatively approved by petrochenkov

It will be put into the queue for this repository once PR CI succeeds.

rust-bors · 2026-09-28T16:21:03Z

❌ Commit edc2f3b has been unapproved due to PR CI failure. Reapprove it with @bors r+ force if you want to ignore the failure.

RalfJung · 2026-09-28T16:44:29Z

@bors r=petrochenkov rollup

rust-bors · 2026-09-28T16:44:33Z

📌 Commit 8846e7e has been tentatively approved by petrochenkov

It will be put into the queue for this repository once PR CI succeeds.

rust-bors · 2026-09-28T17:23:02Z

❌ Commit 8846e7e has been unapproved due to PR CI failure. Reapprove it with @bors r+ force if you want to ignore the failure.

RalfJung · 2026-09-28T17:37:09Z

@bors r=petrochenkov rollup

rust-bors · 2026-09-28T17:37:12Z

📌 Commit 48b2592 has been tentatively approved by petrochenkov

It will be put into the queue for this repository once PR CI succeeds.

@workingjubilee

…r=petrochenkov do not complain about unstable target features on nightly This was brought up in rust-lang#162235 (comment): we currently print a warning on nightly saying that using an unstable target feature will become a hard error. That's a mistake. We could either remove the part of the warning that talks about it becoming a hard error, or we could just hide the warning entirely for unstable features on nighty. I went for the latter -- nightly is meant for experimentation with those features so having un-silenceable warnings is not great. Cc @workingjubilee

…uwer Rollup of 15 pull requests Successful merges: - #158936 (Add `std::fs::{Home|Media}Dirs`) - #129036 (Additional NonZero conversions) - #158997 (Avoid recording unnameable `extern crate` aliases in diagnostic metadata) - #161015 (Stabilize `funnel_shifts` (including `const`)) - #161712 (Stabilize `Result::into_{ok,err}`) - #162493 (Add support for -Zsanitizer-cfi-minimal-runtime) - #162655 (next solver: prefer to select impl candidates over global where-clause candidates) - #162862 (Fix intra doc link resolution when a doc comment is composed of both inner and outer doc comment) - #163200 (make `RustaceansAreAwesome` satisfy trait bounds) - #163331 (Move `Arc` and `Rc` into `rcs` mod) - #163427 (implement #![feature(gca_adts)]) - #163428 (do not complain about unstable target features on nightly) - #163444 (Add `stable_rustc` helper in `run-make-support`) - #163447 (Allow using different index types when reading and writing to tables) - #163450 (Force the correct type variable to never for method resolution on an adjusted never type)

@workingjubilee

…r=petrochenkov do not complain about unstable target features on nightly This was brought up in rust-lang#162235 (comment): we currently print a warning on nightly saying that using an unstable target feature will become a hard error. That's a mistake. We could either remove the part of the warning that talks about it becoming a hard error, or we could just hide the warning entirely for unstable features on nighty. I went for the latter -- nightly is meant for experimentation with those features so having un-silenceable warnings is not great. Cc @workingjubilee

Rollup of 9 pull requests Successful merges: - #161015 (Stabilize `funnel_shifts` (including `const`)) - #161712 (Stabilize `Result::into_{ok,err}`) - #162493 (Add support for -Zsanitizer-cfi-minimal-runtime) - #163427 (implement #![feature(gca_adts)]) - #163390 (add `automatically_derived` attribute documentation) - #163428 (do not complain about unstable target features on nightly) - #163444 (Add `stable_rustc` helper in `run-make-support`) - #163447 (Allow using different index types when reading and writing to tables) - #163459 (Stabilize vec_try_remove)

Rollup of 9 pull requests Successful merges: - rust-lang/rust#161015 (Stabilize `funnel_shifts` (including `const`)) - rust-lang/rust#161712 (Stabilize `Result::into_{ok,err}`) - rust-lang/rust#162493 (Add support for -Zsanitizer-cfi-minimal-runtime) - rust-lang/rust#163427 (implement #![feature(gca_adts)]) - rust-lang/rust#163390 (add `automatically_derived` attribute documentation) - rust-lang/rust#163428 (do not complain about unstable target features on nightly) - rust-lang/rust#163444 (Add `stable_rustc` helper in `run-make-support`) - rust-lang/rust#163447 (Allow using different index types when reading and writing to tables) - rust-lang/rust#163459 (Stabilize vec_try_remove)

Kobzol · 2026-10-23T18:33:02Z

+// FIXME: Once GCC backend is fixed, remove this `ignore-backends`.
+//@ ignore-backends: gcc
+
+// Ensure that on stable we don't suggest restricting with an unsafe trait and we continue


What does this comment mean? It feels like it's not relevant to the test at all.

(I'm porting this to be an UI test now in #164802)

Uh, I probably accidentally copied this over from the run-make test I used as template...

I was not able to make this a UI test because it tests stable-only behavior. But maybe there's now a way to do that?

Yup, since #163664. Thanks for confirming!

Migrate stable-specific run-make tests to UI tests Enabled by rust-lang#163664. I still kept the `stable_bare_rustc` function, as it could be genuinely useful (just not in the way it was used in run-make tests so far). Should help unblock rust-lang#162848. Note that the comment for the unstable target feature test was wrong (rust-lang#163428 (comment)). r? jieyouxu

rustbot added the A-run-make Area: port run-make Makefiles to rmake.rs label Sep 28, 2026

rustbot assigned petrochenkov Sep 28, 2026

rustbot added A-rustc-dev-guide Area: rustc-dev-guide S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 28, 2026

RalfJung commented Sep 28, 2026

View reviewed changes

RalfJung force-pushed the unstable-target-feature branch from c646ae4 to cc5a973 Compare September 28, 2026 08:36

This comment has been minimized.

Sign in to view

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 Sep 28, 2026

RalfJung force-pushed the unstable-target-feature branch 2 times, most recently from 032423d to edc2f3b Compare September 28, 2026 15:39

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 28, 2026

This comment has been minimized.

Sign in to view

rust-bors Bot 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 28, 2026

RalfJung force-pushed the unstable-target-feature branch from edc2f3b to 8846e7e Compare September 28, 2026 16:44

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 28, 2026

This comment has been minimized.

Sign in to view

rust-bors Bot 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 28, 2026

do not complain about unstable target features on nightly

48b2592

RalfJung force-pushed the unstable-target-feature branch from 8846e7e to 48b2592 Compare September 28, 2026 17:36

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 28, 2026

JonathanBrouwer mentioned this pull request Sep 28, 2026

Rollup of 15 pull requests #163460

Closed

tgross35 mentioned this pull request Sep 29, 2026

Rollup of 9 pull requests #163465

Merged

tgross35 mentioned this pull request Sep 29, 2026

Rollup of 9 pull requests #163467

Closed

rust-bors Bot merged commit 5365b21 into rust-lang:main Sep 29, 2026
13 checks passed

rustbot added this to the 1.101.0 milestone Sep 29, 2026

RalfJung deleted the unstable-target-feature branch September 29, 2026 18:30

github-actions Bot mentioned this pull request Oct 3, 2026

Toolchain upgrade to nightly-2026-10-11 flux-rs/flux#1811

Merged

Kobzol reviewed Oct 23, 2026

View reviewed changes

Kobzol mentioned this pull request Oct 24, 2026

Migrate stable-specific run-make tests to UI tests #164802

Open

Conversation

RalfJung commented Sep 28, 2026

Uh oh!

rustbot commented Sep 28, 2026

Uh oh!

rustbot commented Sep 28, 2026

Uh oh!

RalfJung Sep 28, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

jieyouxu Sep 28, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

RalfJung Sep 28, 2026

Choose a reason for hiding this comment

Uh oh!

This comment has been minimized.

petrochenkov commented Sep 28, 2026

Uh oh!

RalfJung commented Sep 28, 2026

Uh oh!

RalfJung commented Sep 28, 2026

Uh oh!

rust-bors Bot commented Sep 28, 2026

Uh oh!

This comment has been minimized.

rust-bors Bot commented Sep 28, 2026

Uh oh!

RalfJung commented Sep 28, 2026

Uh oh!

rust-bors Bot commented Sep 28, 2026

Uh oh!

This comment has been minimized.

rust-bors Bot commented Sep 28, 2026

Uh oh!

RalfJung commented Sep 28, 2026

Uh oh!

rust-bors Bot commented Sep 28, 2026

Uh oh!

Uh oh!

Kobzol Oct 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

RalfJung Oct 24, 2026

Choose a reason for hiding this comment

Uh oh!

Kobzol Oct 24, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

RalfJung Sep 28, 2026 •

edited by rustbot

Loading

jieyouxu Sep 28, 2026 •

edited

Loading

Kobzol Oct 23, 2026 •

edited

Loading