Implement some FIXME methods in the new trait solver

[compiler-errors]

Implement just enough of the solver's response logic to make it not ICE.

Also, fix a bug with no_bound_vars call failing due to canonical bound vars.

r? @lcnr

[rustbot]

Some changes occurred to the core trait solver

cc @lcnr, @compiler-errors

[bors]

☔ The latest upstream changes (presumably #106743) made this pull request unmergeable. Please resolve the merge conflicts.

[lcnr]

r=me after nits

[compiler-errors]

@bors r=lcnr

[bors]

📌 Commit 1de196f has been approved by lcnr

It is now in the queue for this repository.

[lcnr]

ah, this should be resp.certainty. The rest of this hack is fine, but overflow handling is completely wrong because of this.

[compiler-errors]

Wait, this returns value which is just resp.certainty (mapped under instantiate_query_response_and_region_obligations, but for overflows it shouldn't matter, right?)

Otherwise not sure if I understand this comment.

[lcnr]

ah, I was confused sorry 😅 didn't see that you provided resp.certainty twice, once as value and once as certainty

[bors]

⌛ Testing commit 1de196f with merge ae4d89d...

[bors]

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing ae4d89d to master...

[rust-timer]

Finished benchmarking commit (ae4d89d): comparison URL.

Overall result: ✅ improvements - 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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.4%	[-0.5%, -0.3%]	6
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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.4%	[-2.4%, -2.4%]	1
Improvements ✅ (secondary)	-1.9%	[-2.6%, -0.9%]	3
All ❌✅ (primary)	-2.4%	[-2.4%, -2.4%]	1

Cycles

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