new solver normalization improvements

[lcnr]

cool beans

At the core of this PR is a try_normalize_ty which stops for rigid aliases by using commit_if_ok.

Reworks alias-relate to fully normalize both the lhs and rhs and then equate the resulting rigid (or inference) types. This fixes rust-lang/trait-system-refactor-initiative#68 by avoiding the exponential blowup. Also supersedes #116369 by only defining opaque types if the hidden type is rigid.

I removed the stability check in EvalCtxt::evaluate_goal due to rust-lang/trait-system-refactor-initiative#75. While I personally have opinions on how to fix it, that still requires further t-types/@nikomatsakis buy-in, so I removed that for now. Once we've decided on our approach there, we can revert this commit.

r? @compiler-errors

[bors]

☔ The latest upstream changes (presumably #117459) made this pull request unmergeable. Please resolve the merge conflicts.

[compiler-errors]

still draft so marking author so it gets out of my review queue 😆

@rustbot author

[rustbot]

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

[lcnr]

@rustbot ready

[compiler-errors]

🆒 @bors r+

[bors]

📌 Commit fce71ad has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit fce71ad with merge 78efca8...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing 78efca8 to master...

[rust-timer]

Finished benchmarking commit (78efca8): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -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)	1.5%	[0.7%, 2.4%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
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)	1.7%	[1.0%, 2.3%]	2
Regressions ❌ (secondary)	1.4%	[1.1%, 1.7%]	5
Improvements ✅ (primary)	-2.0%	[-2.3%, -1.7%]	2
Improvements ✅ (secondary)	-2.9%	[-2.9%, -2.9%]	1
All ❌✅ (primary)	-0.2%	[-2.3%, 2.3%]	4

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)	0.8%	[0.8%, 0.8%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.8%	[0.8%, 0.8%]	1

Binary size

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

Bootstrap: 675.386s -> 676.982s (0.24%)
Artifact size: 313.58 MiB -> 313.61 MiB (0.01%)

[lqd]

Note for next week's triage if it comes up in the results: deep-vector is currently noisy, and this PR basically only changes the new solver which is disabled by default.