core: drop unmapped ZSTs in array `map` by joboet · Pull Request #152487 · rust-lang/rust

joboet · 2026-02-11T14:30:48Z

Fixes #152211.
Alternative to #152220 and #152248.

This makes the Drain type use the same ZST-handling strategy as slice::IterMut, which stores the remaining length instead of a one-past-the-end pointer when the type is a ZST. I've also removed the const-generic N parameter from Drain to avoid unnecessary monomorphizations.

rustbot · 2026-02-11T14:31:01Z

r? @scottmcm

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scottmcm · 2026-04-18T04:12:31Z

I'll flip this to the same reviewer as #147071
r? oli-obk

rustbot · 2026-04-18T04:12:36Z

oli-obk is not on the review rotation at the moment.
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oli-obk

@bors r+ rollup

View changes since this review

rust-bors · 2026-04-27T08:39:01Z

📌 Commit b9ad3a9 has been approved by oli-obk

It is now in the queue for this repository.

core: drop unmapped ZSTs in array `map` Fixes rust-lang#152211. Alternative to rust-lang#152220 and rust-lang#152248. This makes the `Drain` type use the same ZST-handling strategy as `slice::IterMut`, which stores the remaining length instead of a one-past-the-end pointer when the type is a ZST. I've also removed the const-generic `N` parameter from `Drain` to avoid unnecessary monomorphizations.

…uwer Rollup of 4 pull requests Successful merges: - #152487 (core: drop unmapped ZSTs in array `map`) - #155716 (arm64e: set ptrauth ABI subtype on lib.rmeta Mach-O objects) - #155864 (Fix panic for doc attributes on where predicates) - #155865 (add test for accidentally fixed `binius_field` issue)

rust-bors · 2026-04-27T12:17:52Z

⌛ Testing commit b9ad3a9 with merge 44ae6c2...

Workflow: https://github.com/rust-lang/rust/actions/runs/24994532499

core: drop unmapped ZSTs in array `map` Fixes #152211. Alternative to #152220 and #152248. This makes the `Drain` type use the same ZST-handling strategy as `slice::IterMut`, which stores the remaining length instead of a one-past-the-end pointer when the type is a ZST. I've also removed the const-generic `N` parameter from `Drain` to avoid unnecessary monomorphizations.

JonathanBrouwer · 2026-04-27T12:44:43Z

@bors r-
#155872 (comment)

rust-bors · 2026-04-27T12:44:51Z

This pull request was unapproved.

This PR was contained in a rollup (#155872), which was unapproved.

Auto build was cancelled due to unapproval. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/24994532499

View changes since this unapproval

rustbot · 2026-04-30T11:57:36Z

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.

joboet · 2026-05-01T14:17:15Z

@bors r=@oli-obk

rust-bors · 2026-05-01T14:17:18Z

📌 Commit 14851d2 has been approved by oli-obk

It is now in the queue for this repository.

core: drop unmapped ZSTs in array `map` Fixes rust-lang#152211. Alternative to rust-lang#152220 and rust-lang#152248. This makes the `Drain` type use the same ZST-handling strategy as `slice::IterMut`, which stores the remaining length instead of a one-past-the-end pointer when the type is a ZST. I've also removed the const-generic `N` parameter from `Drain` to avoid unnecessary monomorphizations.

Rollup of 7 pull requests Successful merges: - #152487 (core: drop unmapped ZSTs in array `map`) - #155940 (refactor rustc_on_unimplemented's filtering) - #156020 (Improve source code for `librustdoc/visit_ast.rs`) - #156021 (Clean up some traits) - #156028 (Add a `Local::arg(i)` helper constructor) - #156037 (Add AcceptContext::expect_no_args) - #156040 (Add missing alias to mailmap)

GuillaumeGomez · 2026-05-01T21:36:02Z

Failed in #156056 (comment) with:

warning: feature `reentrant_lock` is declared but not used
  --> library/coretests/tests/lib.rs:99:12
   |
99 | #![feature(reentrant_lock)]
   |            ^^^^^^^^^^^^^^
   |
   = note: `#[warn(unused_features)]` (part of `#[warn(unused)]`) on by default

GuillaumeGomez · 2026-05-01T21:36:05Z

@bors r-

rust-bors · 2026-05-01T21:36:12Z

This pull request was unapproved.

This PR was contained in a rollup (#156056), which was unapproved.

View changes since this unapproval

rust-log-analyzer · 2026-05-05T16:52:49Z

The job aarch64-gnu-llvm-21-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

##[endgroup]
Executing "/scripts/stage_2_test_set2.sh"
+ /scripts/stage_2_test_set2.sh
+ '[' 1 == 1 ']'
+ echo 'PR_CI_JOB set; skipping tidy'
+ SKIP_TIDY='--skip tidy'
+ ../x.py --stage 2 test --skip tidy --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest
PR_CI_JOB set; skipping tidy
##[group]Building bootstrap
    Finished `dev` profile [unoptimized] target(s) in 0.04s
##[endgroup]
---
[TEST] sysroot
[COPY] sysroot_tests source
[PATCH] "sysroot_tests" <- "0027-sysroot_tests-128bit-atomic-operations.patch"
error: patch failed: coretests/tests/lib.rs:2
error: coretests/tests/lib.rs: patch does not apply
Patch failed at 0001 Disable 128bit atomic operations
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
cd "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif/build/sysroot_tests" && "git" "-c" "user.name=Dummy" "-c" "user.email=dummy@example.com" "-c" "core.autocrlf=false" "-c" "commit.gpgSign=false" "am" "/checkout/compiler/rustc_codegen_cranelift/patches/0027-sysroot_tests-128bit-atomic-operations.patch" "-q" exited with status ExitStatus(unix_wait_status(32768))
Command `/checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo run -Zwarnings --target aarch64-unknown-linux-gnu -Zbinary-dep-depinfo -j 4 -Zroot-dir=/checkout --locked --color=always --profile=release --manifest-path /checkout/compiler/rustc_codegen_cranelift/build_system/Cargo.toml -- test --download-dir /checkout/obj/build/cg_clif_download --out-dir /checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif --no-unstable-features --use-backend cranelift --sysroot llvm --skip-test testsuite.extended_sysroot [workdir=/checkout/compiler/rustc_codegen_cranelift]` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/test.rs:3955:25
Executed at: src/bootstrap/src/core/build_steps/test.rs:4000:26

--- BACKTRACE vvv
   0: std::backtrace_rs::backtrace::libunwind::trace
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/../../backtrace/src/backtrace/libunwind.rs:117:9
   1: std::backtrace_rs::backtrace::trace_unsynchronized::<<std::backtrace::Backtrace>::create::{closure#0}>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/../../backtrace/src/backtrace/mod.rs:66:14
   2: <std::backtrace::Backtrace>::create
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/backtrace.rs:331:13
   3: <bootstrap::utils::exec::DeferredCommand>::finish_process
             at /checkout/src/bootstrap/src/utils/exec.rs:939:17
   4: <bootstrap::utils::exec::DeferredCommand>::wait_for_output::<&bootstrap::utils::exec::ExecutionContext>
             at /checkout/src/bootstrap/src/utils/exec.rs:831:21
   5: <bootstrap::utils::exec::ExecutionContext>::run
             at /checkout/src/bootstrap/src/utils/exec.rs:741:45
   6: <bootstrap::utils::exec::BootstrapCommand>::run::<&bootstrap::core::builder::Builder>
             at /checkout/src/bootstrap/src/utils/exec.rs:339:27
   7: <bootstrap::core::build_steps::test::CodegenCranelift as bootstrap::core::builder::Step>::run
             at /checkout/src/bootstrap/src/core/build_steps/test.rs:4000:26
   8: <bootstrap::core::builder::Builder>::ensure::<bootstrap::core::build_steps::test::CodegenCranelift>
             at /checkout/src/bootstrap/src/core/builder/mod.rs:1595:36
   9: <bootstrap::core::build_steps::test::CodegenCranelift as bootstrap::core::builder::Step>::make_run
             at /checkout/src/bootstrap/src/core/build_steps/test.rs:3941:17
  10: <bootstrap::core::builder::StepDescription>::maybe_run
             at /checkout/src/bootstrap/src/core/builder/mod.rs:476:13
  11: bootstrap::core::builder::cli_paths::match_paths_to_steps_and_run
             at /checkout/src/bootstrap/src/core/builder/cli_paths.rs:141:22
  12: <bootstrap::core::builder::Builder>::run_step_descriptions
             at /checkout/src/bootstrap/src/core/builder/mod.rs:1138:9
  13: <bootstrap::core::builder::Builder>::execute_cli
             at /checkout/src/bootstrap/src/core/builder/mod.rs:1117:14
  14: <bootstrap::Build>::build
             at /checkout/src/bootstrap/src/lib.rs:803:25
  15: bootstrap::main
             at /checkout/src/bootstrap/src/bin/main.rs:130:11
  16: <fn() as core::ops::function::FnOnce<()>>::call_once
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/core/src/ops/function.rs:250:5
  17: std::sys::backtrace::__rust_begin_short_backtrace::<fn(), ()>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/sys/backtrace.rs:166:18
  18: std::rt::lang_start::<()>::{closure#0}
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/rt.rs:206:18
  19: <&dyn core::ops::function::Fn<(), Output = i32> + core::panic::unwind_safe::RefUnwindSafe + core::marker::Sync as core::ops::function::FnOnce<()>>::call_once
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/core/src/ops/function.rs:287:21
  20: std::panicking::catch_unwind::do_call::<&dyn core::ops::function::Fn<(), Output = i32> + core::panic::unwind_safe::RefUnwindSafe + core::marker::Sync, i32>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panicking.rs:581:40
  21: std::panicking::catch_unwind::<i32, &dyn core::ops::function::Fn<(), Output = i32> + core::panic::unwind_safe::RefUnwindSafe + core::marker::Sync>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panicking.rs:544:19
  22: std::panic::catch_unwind::<&dyn core::ops::function::Fn<(), Output = i32> + core::panic::unwind_safe::RefUnwindSafe + core::marker::Sync, i32>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panic.rs:359:14
  23: std::rt::lang_start_internal::{closure#0}
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/rt.rs:175:24
  24: std::panicking::catch_unwind::do_call::<std::rt::lang_start_internal::{closure#0}, isize>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panicking.rs:581:40
---
  31: __libc_start_main
  32: _start


Command has failed. Rerun with -v to see more details.
Bootstrap failed while executing `--stage 2 test --skip tidy --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Build completed unsuccessfully in 0:20:40
  local time: Tue May  5 16:48:05 UTC 2026
  network time: Tue, 05 May 2026 16:48:05 GMT
##[error]Process completed with exit code 1.

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Feb 11, 2026

joboet marked this pull request as ready for review February 11, 2026 14:30

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Feb 11, 2026

rustbot assigned scottmcm Feb 11, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Feb 11, 2026

rustbot assigned oli-obk and unassigned scottmcm Apr 18, 2026

oli-obk approved these changes Apr 27, 2026

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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 Apr 27, 2026

JonathanBrouwer mentioned this pull request Apr 27, 2026

Rollup of 3 pull requests #155869

Closed

JonathanBrouwer mentioned this pull request Apr 27, 2026

Rollup of 4 pull requests #155872

Closed

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 Apr 27, 2026

joboet force-pushed the array_map_zst branch from b9ad3a9 to 14851d2 Compare April 30, 2026 11:57

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 May 1, 2026

GuillaumeGomez mentioned this pull request May 1, 2026

Rollup of 7 pull requests #156056

Closed

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 May 1, 2026

core: drop unmapped ZSTs in array map

18b164e

joboet force-pushed the array_map_zst branch from 14851d2 to 18b164e Compare May 5, 2026 16:22

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