Use the query vtable in query_feed plumbing

[Zalathar]

The query_feed function needs to be able to do two important things with (erased) query values: hash them, and debug-print them.

Both of those are things that the query's vtable already knows how to do. So by passing in a vtable to query_feed, we can give it a nicer signature, avoid having to unerase values in the function itself, and clean up some caller-side code as well.

[rustbot]

r? @jdonszelmann

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[Zalathar]

@bors try @rust-timer queue

[rustbot]

This PR was rebased onto a different main 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.

[Zalathar]

@bors try cancel

[rust-bors]

Try build cancelled. Cancelled workflows:

• https://github.com/rust-lang/rust/actions/runs/21509512327

[Zalathar]

@bors try

[rust-bors]

💥 Test timed out after 21600s

[lqd]

@bors try

[rust-bors]

☀️ Try build successful (CI)
Build commit: 7238d58 (7238d58d4d61ca7de1619789c4469d4dad134ec1, parent: e823167aa6f7f03aea8e91208ce9bace8ad9ebf2)

[rust-timer]

Finished benchmarking commit (7238d58): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

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.

@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
Regressions ❌ (secondary)	0.2%	[0.0%, 0.3%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.2%, -0.0%]	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -1.5%, secondary -0.3%)

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)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-1.5%	[-2.1%, -0.9%]	2
Improvements ✅ (secondary)	-2.7%	[-2.7%, -2.7%]	1
All ❌✅ (primary)	-1.5%	[-2.1%, -0.9%]	2

Cycles

Results (secondary 0.6%)

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)	5.7%	[2.1%, 16.3%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-6.3%	[-6.6%, -5.9%]	3
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 474.712s -> 474.274s (-0.09%)
Artifact size: 397.79 MiB -> 397.68 MiB (-0.03%)

[Zalathar]

Perf results look noisy/bimodal, nothing remarkable that I can see.

@rustbot ready

[jdonszelmann]

Not quite comfortable with the internals here, even though it looks correct. Maybe r? @oli-obk ? I think you worked on query feeding no?

[rustbot]

oli-obk is not on the review rotation at the moment.
They may take a while to respond.