eagerly compute sub_relations again

[lcnr]

We still only using them for diagnostics right now. This mostly reverts #119989. Necessary for type inference guidance due to not-yet defined opaque types, cc rust-lang/trait-system-refactor-initiative#182.

We could use them for cycle detection in generalization and it seems desirable to do so in the future. However, this is unsound with the old trait solver as its cache does not track these sub_relations in any way.

We now properly track the sub_relations when canonicalizing so using them in the new solver is totally sound and the performance impact is far more manageable than I thought back in #119989.

r? @compiler-errors

[lcnr]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 54a32a1 with merge 3c1d077...

[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit 26f4ee0 with merge e184142...

[bors]

☀️ Try build successful - checks-actions
Build commit: e184142 (e1841428183d264d2f48328b3de5c0f25654315a)

[rust-timer]

Finished benchmarking commit (e184142): comparison URL.

Overall result: ❌ regressions - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.2%, 1.7%]	75
Regressions ❌ (secondary)	0.4%	[0.2%, 0.7%]	48
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.4%	[0.2%, 1.7%]	75

Max RSS (memory usage)

Results (primary -0.6%, secondary -4.5%)

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)	0.8%	[0.8%, 0.8%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.7%	[-1.1%, -0.4%]	12
Improvements ✅ (secondary)	-4.5%	[-4.5%, -4.5%]	1
All ❌✅ (primary)	-0.6%	[-1.1%, 0.8%]	13

Cycles

Results (primary 0.0%, secondary -1.6%)

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)	0.7%	[0.5%, 0.9%]	3
Regressions ❌ (secondary)	2.2%	[2.2%, 2.2%]	1
Improvements ✅ (primary)	-0.6%	[-0.7%, -0.5%]	3
Improvements ✅ (secondary)	-2.6%	[-2.8%, -2.1%]	4
All ❌✅ (primary)	0.0%	[-0.7%, 0.9%]	6

Binary size

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

Bootstrap: 765.701s -> 765.069s (-0.08%)
Artifact size: 365.36 MiB -> 365.11 MiB (-0.07%)

[bors]

☔ The latest upstream changes (presumably #140474) made this pull request unmergeable. Please resolve the merge conflicts.

[lcnr]

see perf run in #140480 (comment)

[lcnr]

comparing these two perf runs, tracking sub_relations in canonical inputs does slightly worsen performance: https://perf.rust-lang.org/compare.html?start=e1841428183d264d2f48328b3de5c0f25654315a&end=9613271ee15ea18ed41f396fc7aaf4c1f760410a&stat=instructions%3Au

[rust-bors]

☀️ Try build successful (CI)
Build commit: 3f24acc (3f24acc4eaccd5e7db5ddcc0c119c06490377d69, parent: 269d5b56bcfdf2be82213e72ef9a2e4c592a8c6b)

[rust-timer]

Finished benchmarking commit (3f24acc): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

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

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.3%	[0.1%, 1.5%]	49
Regressions ❌ (secondary)	0.8%	[0.1%, 2.7%]	59
Improvements ✅ (primary)	-0.4%	[-0.5%, -0.2%]	5
Improvements ✅ (secondary)	-1.4%	[-2.9%, -0.1%]	13
All ❌✅ (primary)	0.3%	[-0.5%, 1.5%]	54

Max RSS (memory usage)

Results (primary -1.2%, secondary -0.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.0%	[1.0%, 1.0%]	2
Improvements ✅ (primary)	-1.2%	[-1.2%, -1.2%]	1
Improvements ✅ (secondary)	-2.5%	[-2.8%, -2.3%]	2
All ❌✅ (primary)	-1.2%	[-1.2%, -1.2%]	1

Cycles

Results (secondary 2.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.8%	[1.3%, 3.9%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 466.752s -> 466.953s (0.04%)
Artifact size: 391.24 MiB -> 391.35 MiB (0.03%)

[bors]

☔ The latest upstream changes (presumably #145923) made this pull request unmergeable. Please resolve the merge conflicts.

[apiraino]

given the number of changes in the last days I'll switch to waiting on author. switch back when you want a review

@rustbot author

[lcnr]

I want a review

[lcnr]

😁

r? @BoxyUwU though probably

@rustbot ready

[rustbot]

This PR was rebased onto a different master 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.