Extract most code from define_feedable!

[Zalathar]

This PR extracts most of the non-trivial code from the define_feedable! macro (which defines the TyCtxtFeed::$query methods), and moves it to a helper function query_feed_inner written in ordinary non-macro code.

Doing so should make that code easier to read and modify, because it now gets proper IDE support and has explicit trait bounds.

---

There should be no change in compiler behaviour.

I've structured the commits so that the actual extraction part is mostly just whitespace changes, making it easier to review individually with whitespace changes hidden.

[rustbot]

r? @jackh726

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[Zalathar]

No perf changes intended, but let's check:

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: b135ecc (b135ecc5b5ca9773965d5c7368568e9fe2f0f49c, parent: 1a3cdd34629306fa67624eaa60d73687e7fcf855)

[cjgillot]

Could you put this closer to query_get_at and co? It serves a similar purpose.

[Zalathar]

Hmm, the downside would be that it's no longer adjacent to the calling code in define_feedable!, so coordinated changes to both would be much less convenient.

I can move it if you want, but to me it seems better off here.

[cjgillot]

This should be recoverable from dep_kind in a panic message.

[Zalathar]

Ah, via tcx.dep_kind_info(dep_kind).name? That should be easy enough.

[rust-timer]

Finished benchmarking commit (b135ecc): comparison URL.

Overall result: no relevant changes - 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

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

Max RSS (memory usage)

Results (primary -7.0%, secondary -5.7%)

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)	-	-	0
Improvements ✅ (primary)	-7.0%	[-8.3%, -5.6%]	2
Improvements ✅ (secondary)	-5.7%	[-5.7%, -5.7%]	1
All ❌✅ (primary)	-7.0%	[-8.3%, -5.6%]	2

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: 471.633s -> 471.589s (-0.01%)
Artifact size: 388.34 MiB -> 388.35 MiB (0.00%)

[jackh726]

r? @cjgillot

Seems you probably are a better reviewer for this PR.