Hash DefId in rustc_span.

[cjgillot]

This is mostly just moving code around. Changes are simplifications of unneeded callbacks from rustc_span to rustc_middle.

r? @petrochenkov

[cjgillot]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit 4690c4e5acfdc04f0393dff3a3a89ad03779b563 with merge dd1f2ebeae2c9a3f58ba84a82114e3a881cd8a5c...

[bors]

☀️ Try build successful - checks-actions
Build commit: dd1f2ebeae2c9a3f58ba84a82114e3a881cd8a5c (dd1f2ebeae2c9a3f58ba84a82114e3a881cd8a5c)

[rust-timer]

Queued dd1f2ebeae2c9a3f58ba84a82114e3a881cd8a5c with parent c5fbcd3, future comparison URL.

[rust-timer]

Finished benchmarking try commit (dd1f2ebeae2c9a3f58ba84a82114e3a881cd8a5c): 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 label: +S-waiting-on-review -S-waiting-on-perf

[petrochenkov]

#86180 (comment) looks like a very minor but pretty consistent regression.
Perhaps it's better to keep/add methods for more effective hashing of LocalDefId and CrateNum (without going through full DefId) even if they are only used in fn update_disambiguator.

(Their default implementation may go through full DefId though.)

UPD: DummyHashStableContext is used for hashing ExpnData which contains so much data that optimizing CrateNum hashing shouldn't make any difference, so the perf difference is most likely a noise and this comment can be ignored.

[petrochenkov]

@bors r+

[bors]

📌 Commit 72e9589 has been approved by petrochenkov

[bors]

⌛ Testing commit 72e9589 with merge 0f6ba39...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 0f6ba39 to master...