Auto merge of #116455 - matthiaskrgr:rollup-p226a5u, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #116220 (stabilize `Option::as_`(`mut_`)`slice`)
 - #116288 (Add Span to various smir types)
 - #116415 (Move subtyper below reveal_all and change reveal_all)
 - #116428 (Add a note to duplicate diagnostics)
 - #116452 (Do not assert that hidden types don't have erased regions.)

r? `@ghost`
`@rustbot` modify labels: rollup