Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`) #123468

compiler-errors · 2024-04-04T19:16:17Z

Implements impl use<'a, 'b, T, U> Sized syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing all lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to #117587.

We represent this list of captured params as PreciseCapturingArg in AST and HIR, resolving them between rustc_resolve and resolve_bound_vars. Later on, we validate that the opaques only capture the parameters in this list.

We artificially limit the feature to require mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.

We also may need to limit this to require naming all lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.

r? @oli-obk

Tracking issue:

Tracking issue for precise_capturing syntax #123432

compiler/rustc_resolve/src/late.rs

compiler/rustc_hir/src/hir.rs

compiler/rustc_ast_lowering/messages.ftl

compiler/rustc_hir_analysis/src/check/check.rs

oli-obk

first round

compiler/rustc_parse/src/parser/ty.rs

compiler/rustc_resolve/src/late.rs

compiler/rustc_ast_lowering/src/lifetime_collector.rs

compiler/rustc_ast_lowering/src/lib.rs

oli-obk · 2024-04-04T20:13:39Z

tests/ui/impl-trait/precise-capturing/bad-lifetimes.stderr

+   = help: this function's return type contains a borrowed value, but there is no value for it to be borrowed from
+help: consider using the `'static` lifetime, but this is uncommon unless you're returning a borrowed value from a `const` or a `static`, or if you will only have owned values
+   |
+LL | fn no_elided_lt() -> impl use<'static> Sized {}


kinda funny that this suggests something that will also get rejected

tests/ui/impl-trait/precise-capturing/forgot-to-capture-type.stderr

compiler/rustc_ast/src/ast.rs

rustbot · 2024-04-05T00:53:08Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

oli-obk · 2024-04-08T14:59:11Z

@bors r+ rollup=never

bors · 2024-04-08T14:59:14Z

📌 Commit 8a10e6f has been approved by oli-obk

It is now in the queue for this repository.

bors · 2024-04-08T19:15:06Z

☔ The latest upstream changes (presumably #120131) made this pull request unmergeable. Please resolve the merge conflicts.

fmease · 2024-04-13T01:50:11Z

Did someone synchronize the queue? It currently shows up in the queue.
@bors r-

matthiaskrgr · 2024-04-16T07:20:58Z

this is not merged yet lol

Kobzol · 2024-04-16T07:24:14Z

It's almost there, I trust bors to push it through!

matthiaskrgr · 2024-04-16T07:27:02Z

ci hasn't started yet? 😅

Kobzol · 2024-04-16T07:28:40Z

It was already successful (#123468 (comment)), we just need bors to redo it again. (If something fails, I'll circle back to this :) I'm doing triage now, and this was already recorded in the perf database).

bors · 2024-04-16T08:37:45Z

⌛ Testing commit 8ddd280 with merge c002c0a...

rust-log-analyzer · 2024-04-16T08:57:02Z

The job x86_64-gnu-llvm-18 failed! Check out the build log: (web) (plain)

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

test [debuginfo-gdb] tests/debuginfo/var-captured-in-stack-closure.rs ... ok

failures:

---- [debuginfo-gdb] tests/debuginfo/include_string.rs stdout ----
NOTE: compiletest thinks it is using GDB with native rust support
NOTE: compiletest thinks it is using GDB version 15000050

error: gdb failed to execute
status: exit status: 1
command: PYTHONPATH="/checkout/./src/etc" "/usr/bin/gdb" "-quiet" "-batch" "-nx" "-command=/checkout/obj/build/x86_64-unknown-linux-gnu/test/debuginfo/include_string.gdb/include_string.debugger.script"
--- stdout -------------------------------
GNU gdb (Ubuntu 15.0.50.20240403-0ubuntu1) 15.0.50.20240403-git
Copyright (C) 2024 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
Breakpoint 1 at 0x12b3: file /checkout/tests/debuginfo/include_string.rs, line 42.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 1, include_string::main () at /checkout/tests/debuginfo/include_string.rs:42
42     zzz(); // #break
--- stderr -------------------------------
/checkout/obj/build/x86_64-unknown-linux-gnu/test/debuginfo/include_string.gdb/include_string.debugger.script:11: Error in sourced command file:
Attempt to extract a component of a value that is not a structure.
------------------------------------------
------------------------------------------


---- [debuginfo-gdb] tests/debuginfo/vec-slices.rs stdout ----
NOTE: compiletest thinks it is using GDB with native rust support
NOTE: compiletest thinks it is using GDB version 15000050

error: gdb failed to execute
status: exit status: 1
command: PYTHONPATH="/checkout/./src/etc" "/usr/bin/gdb" "-quiet" "-batch" "-nx" "-command=/checkout/obj/build/x86_64-unknown-linux-gnu/test/debuginfo/vec-slices.gdb/vec-slices.debugger.script"
--- stdout -------------------------------
GNU gdb (Ubuntu 15.0.50.20240403-0ubuntu1) 15.0.50.20240403-git
Copyright (C) 2024 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
Breakpoint 1 at 0x1545: file /checkout/tests/debuginfo/vec-slices.rs, line 127.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 1, vec_slices::main () at /checkout/tests/debuginfo/vec-slices.rs:127
127     zzz(); // #break
--- stderr -------------------------------
--- stderr -------------------------------
/checkout/obj/build/x86_64-unknown-linux-gnu/test/debuginfo/vec-slices.gdb/vec-slices.debugger.script:11: Error in sourced command file:
Attempt to extract a component of a value that is not a structure.



failures:

bors · 2024-04-16T08:59:18Z

💔 Test failed - checks-actions

Kobzol · 2024-04-16T09:01:11Z

This CI failure is unrelated to this PR (https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/Depending.20on.20beta.2Funreleased.20OS.2Fpackages.20in.20CI.20jobs). It should be fixed by #123963.

compiler-errors · 2024-04-16T09:32:32Z

@bors retry

bors · 2024-04-16T11:22:39Z

⌛ Testing commit 8ddd280 with merge 4e1f5d9...

bors · 2024-04-16T13:24:55Z

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 4e1f5d9 to master...

bors · 2024-04-16T13:24:55Z

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 4e1f5d9 to master...

rust-timer · 2024-04-16T15:08:43Z

Finished benchmarking commit (4e1f5d9): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.2%]	4
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.8%	[-0.8%, -0.8%]	1
All ❌✅ (primary)	0.2%	[0.2%, 0.2%]	4

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	7.3%	[1.6%, 10.9%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.2%	[-2.2%, -2.2%]	1
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 678.547s -> 678.675s (0.02%)
Artifact size: 316.00 MiB -> 316.10 MiB (0.03%)

rustbot assigned oli-obk Apr 4, 2024

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 Apr 4, 2024

compiler-errors commented Apr 4, 2024

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traviscross mentioned this pull request Apr 4, 2024

Tracking issue for precise_capturing syntax #123432

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traviscross added the F-precise_capturing `#![feature(precise_capturing)]` label Apr 4, 2024

oli-obk reviewed Apr 4, 2024

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oli-obk approved these changes Apr 8, 2024

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bors 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 8, 2024

bors 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 8, 2024

compiler-errors added 10 commits April 15, 2024 16:45

Parsing , pre-lowering support for precise captures

a076eae

Begin AST lowering for precise captures

647b672

Use dedicated PreciseCapturingArg for representing what goes in use<>

fc9e344

Implement resolution, parse use<Self>

c897092

Lower and resolve precise captures in HIR

41cf87b

Validation and other things

42ba57c

Add hir::Node::PreciseCapturingNonLifetimeArg

02d7317

Some ordering and duplication checks

ce89610

Use a path instead of an ident (and stop manually resolving)

52c6b10

More polishing

ac7651c

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Apr 16, 2024

Kobzol mentioned this pull request Apr 16, 2024

Disable two debuginfo tests failing under the future GDB 15 release #123963

Merged

bors 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 16, 2024

bors merged commit 4e1f5d9 into rust-lang:master Apr 16, 2024

rustbot added this to the 1.79.0 milestone Apr 16, 2024

This was referenced Apr 16, 2024

Fix ICE when there is a continue in a labeled block #121682

Closed

Require explicitly marking closures as coroutines #123792

Merged

jackh726 mentioned this pull request Apr 25, 2024

Precise capturing rust-lang/rfcs#3617

Merged

compiler-errors mentioned this pull request Jul 13, 2024

Stabilize opaque type precise capturing (RFC 3617) #127672

Merged

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Implement syntax for impl Trait to specify its captures explicitly (feature(precise_capturing)) #123468

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rust-timer commented Apr 16, 2024

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`) #123468

Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`) #123468

compiler-errors commented Apr 4, 2024 •

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