Access Session and OnDiskCache in rustc_query_system

[cjgillot]

Reduces the boilerplace of implementing the DepContext trait.
The OnDiskCache is accessed directly through a dedicated trait.

[rust-highfive]

r? @ecstatic-morse

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[jyn514]

Just because queries are so hot:

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion

[bors]

⌛ Trying commit 10eecf16565f2335d7e8ac6c284cc9e6b4cc1a6a with merge 87252d22753cd3d9ae6d687cf8b3764dc5c2778b...

[bors]

☀️ Try build successful - checks-actions
Build commit: 87252d22753cd3d9ae6d687cf8b3764dc5c2778b (87252d22753cd3d9ae6d687cf8b3764dc5c2778b)

[rust-timer]

Queued 87252d22753cd3d9ae6d687cf8b3764dc5c2778b with parent 603ab5b, future comparison URL.

[rust-timer]

Finished benchmarking try commit (87252d22753cd3d9ae6d687cf8b3764dc5c2778b): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never
@rustbot modify labels: +S-waiting-on-review -S-waiting-on-perf

[jyn514]

Perf looks like mostly noise I think - improvements of up to 1.5% on instructions counts, but also losses up to .7%.

[crlf0710]

@cjgillot Triage: What's the current status of this?

[jyn514]

@crlf0710 this is waiting on review (although it needs a rebase at some point).

r? @wesleywiser maybe?

[bors]

☔ The latest upstream changes (presumably #80177) made this pull request unmergeable. Please resolve the merge conflicts.

Note that reviewers usually do not review pull requests until merge conflicts are resolved! Once you resolve the conflicts, you should change the labels applied by bors to indicate that your PR is ready for review. Post this as a comment to change the labels:

@rustbot modify labels: +S-waiting-on-review -S-waiting-on-author