Add `Drop::pin_drop` for pinned drops by frank-king · Pull Request #144537 · rust-lang/rust

frank-king · 2025-07-27T14:31:16Z

This PR is part of the pin_ergonomics experiment (the tracking issue is #130494). It allows implementing Drop with a pinned self receiver, which is required for safe pin-projection.

Implementations:

At least and at most one of drop and pin_drop should be implemented.
No direct call of drop or pin_drop. They should only be called by the drop glue.
pin_drop must and must only be used with types that support pin-projection (i.e. types with #[pin_v2]).
Allows writing fn drop(&pin mut self) and desugars to fn pin_drop(&pin mut self). (Will be in the next PRs)

frank-king · 2025-09-21T04:19:22Z

The CI failed because Drop::drop becomes a provided method. I'm afraid it might not be a good way to hack into librustdoc. Is there any other good way to fix it?

rustbot · 2026-05-04T03:43:01Z

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

rustbot · 2026-05-04T03:43:03Z

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.

P8L1 · 2026-05-04T12:41:11Z

Hi @frank-king, from what I can see the latest CI is green now, including the previous lint/linkchecker-related issue. Could you please confirm that this part is fully resolved on your side as well?

I also plan to work on the remaining unchecked item in the PR description:

Allows writing fn drop(&pin mut self) and desugars to fn pin_drop(&pin mut self). (Will be in the next PRs)

I’ll prepare that as a follow-up PR so this Drop::pin_drop work can keep moving forward.

frank-king · 2026-05-04T12:53:59Z

@rustbot ready

petrochenkov · 2026-05-04T15:00:16Z

@bors r+

rust-bors · 2026-05-04T15:00:20Z

📌 Commit fa600c5 has been approved by petrochenkov

It is now in the queue for this repository.

Add `Drop::pin_drop` for pinned drops This PR is part of the `pin_ergonomics` experiment (the tracking issue is #130494). It allows implementing `Drop` with a pinned `self` receiver, which is required for safe pin-projection. Implementations: - [x] At least and at most one of `drop` and `pin_drop` should be implemented. - [x] No direct call of `drop` or `pin_drop`. They should only be called by the drop glue. - [x] `pin_drop` must and must only be used with types that support pin-projection (i.e. types with `#[pin_v2]`). - [ ] Allows writing `fn drop(&pin mut self)` and desugars to `fn pin_drop(&pin mut self)`. (Will be in the next PRs)

rust-log-analyzer · 2026-05-04T18:35:54Z

The job x86_64-gnu-llvm-21-1 failed! Check out the build log: (web) (plain enhanced) (plain)

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

test expr_store::tests::body::async_fn_weird_param_patterns ... ok
test expr_store::scope::tests::test_shadow_variable ... ok
test expr_store::scope::tests::while_let_adds_binding ... ok
test expr_store::tests::body::block::inner_item_smoke ... ok
error: test failed, to rerun pass `-p hir-def --lib`

Caused by:
  process didn't exit successfully: `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/hir_def-c439368f2b64a049 '--skip=tests::smoke_test_real_sysroot_cargo' --skip=check_code_formatting -Z unstable-options --format json` (signal: 11, SIGSEGV: invalid memory reference)
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Build completed unsuccessfully in 1:11:02
  local time: Mon May  4 18:35:38 UTC 2026
  network time: Mon, 04 May 2026 18:35:39 GMT
##[error]Process completed with exit code 1.

rust-bors · 2026-05-04T18:36:52Z

💔 Test for 13a5a99 failed: CI. Failed job:

auto - x86_64-gnu-llvm-21-1 (web logs, enhanced plaintext logs)

JonathanBrouwer · 2026-05-04T18:44:31Z

@bors retry

P8L1 · 2026-05-04T19:08:25Z

@frank-king I opened a stacked follow-up PR for the remaining sugar item:

frank-king#9

It implements fn drop(&pin mut self) as sugar for Drop::pin_drop on top of feature/pin-drop.

The implementation keeps the remap at resolver/HIR, lowering time: the resolver recognises the sugar only for the actual #[lang = "drop"] trait, resolves it as pin_drop, and lowering emits HIR with ident pin_drop. It leaves the existing Drop validation, drop glue, and direct-call checks unchanged.

I also added coverage for hosted Drop, qualified std::ops::Drop / core::ops::Drop, local no-core #[lang = "drop"], non-Drop traits named Drop, non-Drop traits with drop / pin_drop, exact receiver rejection cases, and feature-gate behaviour.

Happy to adjust the approach if you would prefer the sugar to be handled at a different compiler boundary.

rust-log-analyzer · 2026-05-04T22:34:25Z

The job x86_64-gnu-llvm-21-3 failed! Check out the build log: (web) (plain enhanced) (plain)

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

##[endgroup]
[TIMING:end] tool::ToolBuild { build_compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu, tool: "linkchecker", path: "src/tools/linkchecker", mode: ToolBootstrap, source_type: InTree, extra_features: [], allow_features: "", cargo_args: [], artifact_kind: Binary } -- 0.160
[TIMING:end] tool::Linkchecker { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu } -- 0.000
##[group]Testing stage1 Linkcheck (x86_64-unknown-linux-gnu)
reference/print.html:44444: broken link fragment `#tymethod.drop` pointing to `core/ops/drop/trait.Drop.html`
reference/destructors.html:197: broken link fragment `#tymethod.drop` pointing to `core/ops/drop/trait.Drop.html`
checked links in: 31.6s
number of HTML files scanned: 60134
number of HTML redirects found: 21239
number of links checked: 2876699
number of links ignored due to external: 150637
---

--- BACKTRACE vvv
   0: <bootstrap::utils::exec::DeferredCommand>::finish_process
             at /checkout/src/bootstrap/src/utils/exec.rs:939:17
   1: <bootstrap::utils::exec::DeferredCommand>::wait_for_output::<&bootstrap::utils::exec::ExecutionContext>
             at /checkout/src/bootstrap/src/utils/exec.rs:831:21
   2: <bootstrap::utils::exec::ExecutionContext>::run
             at /checkout/src/bootstrap/src/utils/exec.rs:741:45
   3: <bootstrap::utils::exec::BootstrapCommand>::run::<&bootstrap::core::builder::Builder>
             at /checkout/src/bootstrap/src/utils/exec.rs:339:27
   4: <bootstrap::core::build_steps::test::Linkcheck as bootstrap::core::builder::Step>::run
             at /checkout/src/bootstrap/src/core/build_steps/test.rs:191:77
   5: <bootstrap::core::builder::Builder>::ensure::<bootstrap::core::build_steps::test::Linkcheck>
             at /checkout/src/bootstrap/src/core/builder/mod.rs:1595:36
   6: <bootstrap::core::build_steps::test::Linkcheck as bootstrap::core::builder::Step>::make_run
             at /checkout/src/bootstrap/src/core/build_steps/test.rs:137:21
   7: <bootstrap::core::builder::StepDescription>::maybe_run
             at /checkout/src/bootstrap/src/core/builder/mod.rs:476:13
   8: bootstrap::core::builder::cli_paths::match_paths_to_steps_and_run
             at /checkout/src/bootstrap/src/core/builder/cli_paths.rs:141:22
   9: <bootstrap::core::builder::Builder>::run_step_descriptions
             at /checkout/src/bootstrap/src/core/builder/mod.rs:1138:9
  10: <bootstrap::core::builder::Builder>::execute_cli
             at /checkout/src/bootstrap/src/core/builder/mod.rs:1117:14
  11: <bootstrap::Build>::build
             at /checkout/src/bootstrap/src/lib.rs:803:25
  12: bootstrap::main
             at /checkout/src/bootstrap/src/bin/main.rs:130:11
  13: <fn() as core::ops::function::FnOnce<()>>::call_once
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/core/src/ops/function.rs:250:5
  14: std::sys::backtrace::__rust_begin_short_backtrace::<fn(), ()>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/sys/backtrace.rs:166:18
  15: std::rt::lang_start::<()>::{closure#0}
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/rt.rs:206:18
  16: <&dyn core::ops::function::Fn<(), Output = i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe as core::ops::function::FnOnce<()>>::call_once
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/core/src/ops/function.rs:287:21
  17: std::panicking::catch_unwind::do_call::<&dyn core::ops::function::Fn<(), Output = i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe, i32>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panicking.rs:581:40
  18: std::panicking::catch_unwind::<i32, &dyn core::ops::function::Fn<(), Output = i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panicking.rs:544:19
  19: std::panic::catch_unwind::<&dyn core::ops::function::Fn<(), Output = i32> + core::marker::Sync + core::panic::unwind_safe::RefUnwindSafe, i32>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panic.rs:359:14
  20: std::rt::lang_start_internal::{closure#0}
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/rt.rs:175:24
  21: std::panicking::catch_unwind::do_call::<std::rt::lang_start_internal::{closure#0}, isize>
             at /rustc/ef0fb8a2563200e322fa4419f09f65a63742038c/library/std/src/panicking.rs:581:40
---
  28: __libc_start_main
  29: _start


Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 1:08:37
  local time: Mon May  4 22:34:10 UTC 2026
  network time: Mon, 04 May 2026 22:34:10 GMT
##[error]Process completed with exit code 1.
##[group]Run echo "disk usage:"

rust-bors · 2026-05-04T22:35:32Z

💔 Test for edafd5c failed: CI. Failed job:

auto - x86_64-gnu-llvm-21-3 (web logs, enhanced plaintext logs)

petrochenkov · 2026-05-05T11:19:47Z

Broken links in the reference again.
@rustbot author

P8L1 · 2026-05-05T14:50:43Z

@frank-king @petrochenkov I opened a Reference PR for the current linkchecker failure: rust-lang/reference#2261

It avoids the direct core::ops::Drop::drop method-fragment link that resolves to the stale #tymethod.drop anchor after this PR makes Drop::drop a provided/default method.

ehuss · 2026-05-05T18:52:07Z

I think for fixing the test failure, I think I would prefer to do something like this:

diff --git a/src/ci/docker/scripts/x86_64-gnu-llvm3.sh b/src/ci/docker/scripts/x86_64-gnu-llvm3.sh
index 17eb2cea59a..d2989b3aae6 100755
--- a/src/ci/docker/scripts/x86_64-gnu-llvm3.sh
+++ b/src/ci/docker/scripts/x86_64-gnu-llvm3.sh
@@ -4,7 +4,9 @@ set -ex

 ##### Test stage 1 #####

-../x.py --stage 1 test --skip src/tools/tidy
+# linkchecker is skipped because mixing old rustc/rustdoc with new standard
+# library causes problems with generating correct links.
+../x.py --stage 1 test --skip src/tools/tidy --skip src/tools/linkchecker

 # Run the `mir-opt` tests again but this time for a 32-bit target.
 # This enforces that tests using `// EMIT_MIR_FOR_EACH_BIT_WIDTH` have

Generally I think it is too problematic to try to get the linkchecks working with --stage 1.

cc @jieyouxu @Kobzol in case you want to weigh in on this kind of change.

This was previously discussed at https://rust-lang.zulipchat.com/#narrow/channel/326414-t-infra.2Fbootstrap/topic/Skipping.20stage.201.20tests/with/583642338 for a closely related issue. In this case, I don't think we can employ easy tricks to make this work in the general case.

frank-king force-pushed the feature/pin-drop branch from 362f769 to 1497185 Compare July 27, 2025 14:31