fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions by andjsrk · Pull Request #150385 · rust-lang/rust

andjsrk · 2025-12-26T01:18:59Z

AFAIK [0; 3] is basically a syntax sugar for [0, 0, 0] so it should return whether the repeat's element can have side effects, like what it does on arrays.
And it seems that the rule for unary operators and indexings can be applied to binary operators as well.

rustbot · 2025-12-26T01:19:05Z

r? @jdonszelmann

rustbot has assigned @jdonszelmann.
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

Kivooeo · 2025-12-26T13:17:34Z

Would you like to add a test for this, to reflect new behaviour you changed here

Because on a first glance it's not obvious (at least to me)

andjsrk · 2025-12-27T01:20:27Z

I'm not sure where should I add a test:

tests/ui/expr.rs - Expr::can_have_side_effects is used in a few minor(in my opinion) places and is used widely in Clippy rather than rustc. If I decide to add a test in there, I guess testing code would look pretty unintuitive (could be improved by comments though).
compiler/rustc_hir/src/hir/tests.rs - maybe I should add tests here, but I guess runtime test is needed (not just checking successful compilation) and I have no idea about how to create an Expr...

jdonszelmann · 2026-01-06T02:04:47Z

I agree with @Kivooeo here: something has to be tested. A ui test will show a piece of rust code now compiling (or warning) differently. I think this is supposed to change something about the diagnostics of binop expressions and array expressions. So ideally, I'd see a uitest showing a diagnostic that is different. In fact, I see some tests that failed in CI, likely because of this diagnostics change. If you run x test tests/ui/<specific-test> --bless it will update the expected output, which you can commit, to show what diagnostics changed from this change. Maybe you want to also add a specific test for the exact changed diagnostics behavior after this PR. Let me know if that makes sense!

@rustbot author

rustbot · 2026-01-06T02:04:51Z

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

rustbot · 2026-01-06T11:18:23Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

andjsrk · 2026-01-06T11:27:22Z

Maybe you want to also add a specific test for the exact changed diagnostics behavior after this PR.

@jdonszelmann I'm going to add a test for repeats([x; N]) as it seems no test checks Expr::can_have_side_effects on repeats, but as I asked above I have no idea about where should I add a test, could you let me know?

Kivooeo · 2026-01-06T11:30:10Z

Add please this test to tests/ui/repeat-expr/

And I'm not sure why this changes to clippy were made?

andjsrk · 2026-01-06T11:39:59Z

clippy::needless_match relies on Expr::can_have_side_effects and it warns some code in the UI test for clippy::manual_clamp.
clippy::needless_bitwise_bool has test cases that require improvement of Expr::can_have_side_effects and some of them are resolved now.

These are the cause of test failures in CI and so I fixed them, did I something wrong?

andjsrk · 2026-01-06T18:34:40Z

@rustbot ready

samueltardieu · 2026-01-07T08:47:03Z

The Clippy part looks ok.

jdonszelmann · 2026-01-08T23:36:23Z

yea, I think this looks reasonable. @bors r=jdonszelmann,samueltardieu rollup

jdonszelmann · 2026-01-08T23:38:16Z

actually, stop, @bors r-

rust-bors · 2026-01-08T23:38:19Z

Commit d848437 has been unapproved.

jdonszelmann · 2026-01-08T23:38:32Z

I realised that I would also quite like to see a test for the binary operator change here. After that r=me

jdonszelmann · 2026-01-08T23:38:41Z

@rustbot author

andjsrk · 2026-01-09T09:01:09Z

@bors r=jdonszelmann

rust-bors · 2026-01-09T09:01:12Z

@andjsrk: 🔑 Insufficient privileges: not in review users

andjsrk · 2026-01-09T09:01:37Z

@rustbot ready

andjsrk · 2026-01-09T09:09:13Z

@jdonszelmann I have no permission, please take action on this

samueltardieu · 2026-01-09T09:38:19Z

@bors r=jdonszelmann,samueltardieu rollup

rust-bors · 2026-01-09T09:38:23Z

📌 Commit 561b592 has been approved by jdonszelmann,samueltardieu

It is now in the queue for this repository.

jdonszelmann · 2026-01-09T10:21:03Z

Thanks @samueltardieu :3

@ghost

Rollup of 11 pull requests Successful merges: - #150272 (docs(core): update `find()` and `rfind()` examples) - #150385 (fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions) - #150561 (Finish transition from `semitransparent` to `semiopaque` for `rustc_macro_transparency`) - #150574 (Clarify `MoveData::init_loc_map`.) - #150762 (Use functions more in rustdoc GUI tests) - #150808 (rename the `derive_{eq, clone_copy}` features to `*_internals`) - #150816 (Fix trait method anchor disappearing before user can click on it) - #150821 (tests/ui/borrowck/issue-92157.rs: Remove (bug not fixed)) - #150829 (make attrs actually use `Target::GenericParam`) - #150834 (Add tracking issue for `feature(multiple_supertrait_upcastable)`) - #150864 (The aarch64-unknown-none target requires NEON, so the docs were wrong.) r? @ghost

Rollup merge of #150385 - fix-expr-can-have-side-effects, r=jdonszelmann,samueltardieu fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions AFAIK `[0; 3]` is basically a syntax sugar for `[0, 0, 0]` so it should return whether the repeat's element can have side effects, like what it does on arrays. And it seems that the rule for unary operators and indexings can be applied to binary operators as well.

@ghost

Rollup of 11 pull requests Successful merges: - rust-lang/rust#150272 (docs(core): update `find()` and `rfind()` examples) - rust-lang/rust#150385 (fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions) - rust-lang/rust#150561 (Finish transition from `semitransparent` to `semiopaque` for `rustc_macro_transparency`) - rust-lang/rust#150574 (Clarify `MoveData::init_loc_map`.) - rust-lang/rust#150762 (Use functions more in rustdoc GUI tests) - rust-lang/rust#150808 (rename the `derive_{eq, clone_copy}` features to `*_internals`) - rust-lang/rust#150816 (Fix trait method anchor disappearing before user can click on it) - rust-lang/rust#150821 (tests/ui/borrowck/issue-92157.rs: Remove (bug not fixed)) - rust-lang/rust#150829 (make attrs actually use `Target::GenericParam`) - rust-lang/rust#150834 (Add tracking issue for `feature(multiple_supertrait_upcastable)`) - rust-lang/rust#150864 (The aarch64-unknown-none target requires NEON, so the docs were wrong.) r? @ghost

…jdonszelmann,samueltardieu fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions AFAIK `[0; 3]` is basically a syntax sugar for `[0, 0, 0]` so it should return whether the repeat's element can have side effects, like what it does on arrays. And it seems that the rule for unary operators and indexings can be applied to binary operators as well.

@ghost

Rollup of 11 pull requests Successful merges: - rust-lang/rust#150272 (docs(core): update `find()` and `rfind()` examples) - rust-lang/rust#150385 (fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions) - rust-lang/rust#150561 (Finish transition from `semitransparent` to `semiopaque` for `rustc_macro_transparency`) - rust-lang/rust#150574 (Clarify `MoveData::init_loc_map`.) - rust-lang/rust#150762 (Use functions more in rustdoc GUI tests) - rust-lang/rust#150808 (rename the `derive_{eq, clone_copy}` features to `*_internals`) - rust-lang/rust#150816 (Fix trait method anchor disappearing before user can click on it) - rust-lang/rust#150821 (tests/ui/borrowck/issue-92157.rs: Remove (bug not fixed)) - rust-lang/rust#150829 (make attrs actually use `Target::GenericParam`) - rust-lang/rust#150834 (Add tracking issue for `feature(multiple_supertrait_upcastable)`) - rust-lang/rust#150864 (The aarch64-unknown-none target requires NEON, so the docs were wrong.) r? @ghost

@ghost

Rollup of 11 pull requests Successful merges: - rust-lang/rust#150272 (docs(core): update `find()` and `rfind()` examples) - rust-lang/rust#150385 (fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions) - rust-lang/rust#150561 (Finish transition from `semitransparent` to `semiopaque` for `rustc_macro_transparency`) - rust-lang/rust#150574 (Clarify `MoveData::init_loc_map`.) - rust-lang/rust#150762 (Use functions more in rustdoc GUI tests) - rust-lang/rust#150808 (rename the `derive_{eq, clone_copy}` features to `*_internals`) - rust-lang/rust#150816 (Fix trait method anchor disappearing before user can click on it) - rust-lang/rust#150821 (tests/ui/borrowck/issue-92157.rs: Remove (bug not fixed)) - rust-lang/rust#150829 (make attrs actually use `Target::GenericParam`) - rust-lang/rust#150834 (Add tracking issue for `feature(multiple_supertrait_upcastable)`) - rust-lang/rust#150864 (The aarch64-unknown-none target requires NEON, so the docs were wrong.) r? @ghost

@ghost

Rollup of 11 pull requests Successful merges: - rust-lang/rust#150272 (docs(core): update `find()` and `rfind()` examples) - rust-lang/rust#150385 (fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions) - rust-lang/rust#150561 (Finish transition from `semitransparent` to `semiopaque` for `rustc_macro_transparency`) - rust-lang/rust#150574 (Clarify `MoveData::init_loc_map`.) - rust-lang/rust#150762 (Use functions more in rustdoc GUI tests) - rust-lang/rust#150808 (rename the `derive_{eq, clone_copy}` features to `*_internals`) - rust-lang/rust#150816 (Fix trait method anchor disappearing before user can click on it) - rust-lang/rust#150821 (tests/ui/borrowck/issue-92157.rs: Remove (bug not fixed)) - rust-lang/rust#150829 (make attrs actually use `Target::GenericParam`) - rust-lang/rust#150834 (Add tracking issue for `feature(multiple_supertrait_upcastable)`) - rust-lang/rust#150864 (The aarch64-unknown-none target requires NEON, so the docs were wrong.) r? @ghost

@ghost

Rollup of 11 pull requests Successful merges: - rust-lang/rust#150272 (docs(core): update `find()` and `rfind()` examples) - rust-lang/rust#150385 (fix `Expr::can_have_side_effects` for `[x; N]` style array literal and binary expressions) - rust-lang/rust#150561 (Finish transition from `semitransparent` to `semiopaque` for `rustc_macro_transparency`) - rust-lang/rust#150574 (Clarify `MoveData::init_loc_map`.) - rust-lang/rust#150762 (Use functions more in rustdoc GUI tests) - rust-lang/rust#150808 (rename the `derive_{eq, clone_copy}` features to `*_internals`) - rust-lang/rust#150816 (Fix trait method anchor disappearing before user can click on it) - rust-lang/rust#150821 (tests/ui/borrowck/issue-92157.rs: Remove (bug not fixed)) - rust-lang/rust#150829 (make attrs actually use `Target::GenericParam`) - rust-lang/rust#150834 (Add tracking issue for `feature(multiple_supertrait_upcastable)`) - rust-lang/rust#150864 (The aarch64-unknown-none target requires NEON, so the docs were wrong.) r? @ghost

fix Expr::can_have_side_effects for repeat and binary expressions
a6b005a

rustbot added 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 Dec 26, 2025

rustbot assigned jdonszelmann Dec 26, 2025

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 Jan 6, 2026

accept test changes related to binary ops
bd5526c

rustbot added the T-clippy Relevant to the Clippy team. label Jan 6, 2026

andjsrk added 2 commits January 7, 2026 00:51

add test for repeats
021a551

rename test
61ca012

This comment has been minimized.
Sign in to view

format
f805d1b

This comment has been minimized.
Sign in to view

update expected output as well
c73b64b

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 Jan 6, 2026

add more information in comment
d848437

rust-borsBot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jan 8, 2026

rust-borsBot removed the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jan 8, 2026

add test for binary ops
561b592

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 Jan 9, 2026

rust-borsBot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jan 9, 2026

rust-borsBot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 9, 2026

GuillaumeGomez mentioned this pull request Jan 9, 2026
Rollup of 11 pull requests #150866
Merged

rust-borsBot merged commit 09575ec into rust-lang:mainJan 9, 2026
11 checks passed

rustbot added this to the 1.94.0 milestone Jan 9, 2026

github-actionsBot mentioned this pull request Jan 27, 2026
Toolchain upgrade to nightly-2026-02-09 flux-rs/flux#1345
Closed

Uh oh!

Uh oh!

Conversation

andjsrk commented Dec 26, 2025• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Dec 26, 2025

Uh oh!

This comment has been minimized.

Kivooeo commented Dec 26, 2025

Uh oh!

andjsrk commented Dec 27, 2025• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

jdonszelmann commented Jan 6, 2026

Uh oh!

rustbot commented Jan 6, 2026

Uh oh!

rustbot commented Jan 6, 2026

Uh oh!

andjsrk commented Jan 6, 2026

Uh oh!

Kivooeo commented Jan 6, 2026

Uh oh!

andjsrk commented Jan 6, 2026• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

This comment has been minimized.

This comment has been minimized.

andjsrk commented Jan 6, 2026

Uh oh!

samueltardieu commented Jan 7, 2026

Uh oh!

jdonszelmann commented Jan 8, 2026

Uh oh!

jdonszelmann commented Jan 8, 2026

Uh oh!

rust-borsBot commented Jan 8, 2026

Uh oh!

jdonszelmann commented Jan 8, 2026

Uh oh!

jdonszelmann commented Jan 8, 2026

Uh oh!

andjsrk commented Jan 9, 2026

Uh oh!

rust-borsBot commented Jan 9, 2026

Uh oh!

andjsrk commented Jan 9, 2026

Uh oh!

andjsrk commented Jan 9, 2026

Uh oh!

samueltardieu commented Jan 9, 2026

Uh oh!

rust-borsBot commented Jan 9, 2026

Uh oh!

jdonszelmann commented Jan 9, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

andjsrk commented Dec 26, 2025•
edited
Loading

andjsrk commented Dec 27, 2025•
edited
Loading

andjsrk commented Jan 6, 2026•
edited
Loading