Permit recursive weak type aliases #113201

oli-obk · 2023-06-30T13:57:15Z

I saw #63097 and thought "we can do ~~better~~ funnier". So here it is. It's not useful, but it's certainly something. This may actually become feasible with lazy norm (so in 5 years (constant, not reducing over time)).

r? @estebank

cc @GuillaumeGomez

rustbot · 2023-06-30T13:57:23Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @estebank (or someone else) soon.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

@rustbot author: the review is finished, PR author should check the comments and take action accordingly
@rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

estebank · 2023-06-30T16:05:02Z

@bors r+

bors · 2023-06-30T16:05:04Z

📌 Commit 01fcce9e0e60c73311b0d94c17f950ac7fded7fa has been approved by estebank

It is now in the queue for this repository.

compiler-errors · 2023-06-30T17:26:45Z

compiler/rustc_hir_analysis/src/astconv/mod.rs

+        // Lazily compute this to avoid cycles under `lazy_type_alias`
+        let mut ty = None;
+        let mut ty = || *ty.get_or_insert_with(|| self.tcx().at(span).type_of(did));

        if matches!(self.tcx().def_kind(did), DefKind::TyAlias)
-            && (ty.skip_binder().has_opaque_types() || self.tcx().features().lazy_type_alias)
+            && (self.tcx().features().lazy_type_alias || ty().skip_binder().has_opaque_types())


This lazy caching of the ty variable seems a bit convoluted imo. I think the control flow is clearer if we just duplicate the weak alias branch by first doing:

if tcx.features.lazy_type_alias { make the projection } else { // comment going here explaining the query cycle avoidance in the above branch let ty = tcx.type_of(...); if ty.has_opaques() { // old comment mentioning opaques goes here make projection } else { ty.subst(..) } }

I guess I'll do that as a follow-up since this PR is already approved, though.

compiler-errors · 2023-06-30T17:29:22Z

tests/ui/infinite/infinite-vec-type-recursion.feature.stderr

+error[E0275]: overflow evaluating the requirement `X`
+  --> $DIR/infinite-vec-type-recursion.rs:9:20
+   |
+LL | fn main() { let b: X = Vec::new(); }
+   |                    ^


Hm, I consider this to be a worse error message than the query cycle, since at least that one's got spans pointing to all the aliases participating in the cycle. But the fixes to overflow handling in weak aliases seems necessary regardless, though, since you could probably have recreated this condition using TAITs.

oli-obk · 2023-06-30T18:08:53Z

@bors r-

bors · 2023-07-14T17:38:02Z

☔ The latest upstream changes (presumably #113591) made this pull request unmergeable. Please resolve the merge conflicts.

JohnCSimon · 2023-08-27T05:25:01Z

triage: @oli-obk can you please address the merge conflicts and assign to reviewer?

oli-obk · 2023-08-30T10:39:23Z

@bors r=estebank,compiler-errors

bors · 2023-08-30T10:39:25Z

📌 Commit 09c793e80c18025b2cbe965071b7627ac4a538de has been approved by estebank,compiler-errors

It is now in the queue for this repository.

bors · 2023-08-30T11:30:39Z

⌛ Testing commit 09c793e80c18025b2cbe965071b7627ac4a538de with merge 1e65ca4280c4e894138b84b4245286efc9199059...

oli-obk · 2023-08-30T11:55:39Z

@bors r=estebank,compiler-errors

bors · 2023-08-30T11:55:42Z

📌 Commit 5d850e0 has been approved by estebank,compiler-errors

It is now in the queue for this repository.

rust-log-analyzer · 2023-08-30T11:58:45Z

A job failed! Check out the build log: (web) (plain)

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

bors · 2023-08-30T13:59:01Z

⌛ Testing commit 5d850e0 with merge cec1940b1cfc92a766635a2117bd856d98be10a8...

oli-obk · 2023-08-30T18:26:10Z

@bors ping

rust-timer · 2023-08-31T04:42:47Z

Finished benchmarking commit (cec1940b1cfc92a766635a2117bd856d98be10a8): 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

Warning ⚠: The following benchmark(s) failed to build:

image-0.24.1

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)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.2%	[-2.2%, -2.2%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.6%	[-2.2%, 0.9%]	2

Max RSS (memory usage)

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)	2.1%	[1.8%, 2.4%]	2
Improvements ✅ (primary)	-0.9%	[-0.9%, -0.9%]	1
Improvements ✅ (secondary)	-2.6%	[-3.7%, -2.0%]	4
All ❌✅ (primary)	-0.9%	[-0.9%, -0.9%]	1

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)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.6%	[-2.1%, 0.9%]	2

Binary size

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

Bootstrap: 632.146s -> 631.714s (-0.07%)
Artifact size: 316.62 MiB -> 316.59 MiB (-0.01%)

oli-obk · 2023-08-31T07:37:42Z

@bors r-

oli-obk · 2023-08-31T07:38:23Z

@bors try @rust-timer queue

bors · 2023-08-31T07:38:33Z

⌛ Trying commit 5d850e0 with merge 85e17c5d3df8e83bde2f0783dc9600177063c904...

bors · 2023-08-31T08:49:43Z

☀️ Try build successful - checks-actions
Build commit: 85e17c5d3df8e83bde2f0783dc9600177063c904 (85e17c5d3df8e83bde2f0783dc9600177063c904)

rust-timer · 2023-08-31T23:07:16Z

Finished benchmarking commit (85e17c5d3df8e83bde2f0783dc9600177063c904): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.5%	[-0.5%, -0.5%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

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)	1.4%	[1.1%, 1.7%]	3
Regressions ❌ (secondary)	2.8%	[1.7%, 4.4%]	3
Improvements ✅ (primary)	-1.0%	[-1.0%, -1.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.8%	[-1.0%, 1.7%]	4

Cycles

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

Binary size

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

Bootstrap: 631.413s -> 631.275s (-0.02%)
Artifact size: 316.57 MiB -> 316.51 MiB (-0.02%)

oli-obk · 2023-09-01T06:45:06Z

@bors r=estebank,compiler-errors

bors · 2023-09-01T06:45:08Z

📌 Commit 5d850e0 has been approved by estebank,compiler-errors

It is now in the queue for this repository.

bors · 2023-09-01T07:10:25Z

⌛ Testing commit 5d850e0 with merge 96f62fc...

bors · 2023-09-01T09:06:55Z

☀️ Test successful - checks-actions
Approved by: estebank,compiler-errors
Pushing 96f62fc to master...

rust-timer · 2023-09-02T00:46:06Z

Finished benchmarking commit (96f62fc): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

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)	1.4%	[0.6%, 1.8%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.4%	[0.6%, 1.8%]	3

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)	2.9%	[2.9%, 3.0%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 632.086s -> 631.878s (-0.03%)
Artifact size: 316.25 MiB -> 316.40 MiB (0.05%)

rustbot assigned estebank Jun 30, 2023

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 Jun 30, 2023

GuillaumeGomez approved these changes Jun 30, 2023

View reviewed changes

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 Jun 30, 2023

compiler-errors reviewed Jun 30, 2023

View reviewed changes

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 Jun 30, 2023

oli-obk force-pushed the recursive_type_alias branch from 01fcce9 to 09c793e Compare August 30, 2023 10:38

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 30, 2023

Permit recursive weak type aliases

5d850e0

oli-obk force-pushed the recursive_type_alias branch from 09c793e to 5d850e0 Compare August 30, 2023 11:55

oli-obk closed this Aug 30, 2023

oli-obk reopened this Aug 30, 2023

rustbot added the perf-regression Performance regression. label Aug 31, 2023

oli-obk removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. merged-by-bors This PR was explicitly merged by bors. perf-regression Performance regression. labels Aug 31, 2023

bors added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Aug 31, 2023

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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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 1, 2023

bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 1, 2023

bors merged commit 96f62fc into rust-lang:master Sep 1, 2023

rustbot added this to the 1.74.0 milestone Sep 1, 2023

GuillaumeGomez mentioned this pull request Oct 5, 2023

Tracking issue for lazy type aliases #112792

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Permit recursive weak type aliases #113201

Permit recursive weak type aliases #113201

oli-obk commented Jun 30, 2023

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estebank commented Jun 30, 2023

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Permit recursive weak type aliases #113201

Permit recursive weak type aliases #113201

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oli-obk commented Jun 30, 2023

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rust-timer commented Aug 31, 2023

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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Overall result: ✅ improvements - no action needed

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rust-timer commented Sep 2, 2023

Overall result: no relevant changes - no action needed

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