Exhaustiveness: Reveal empty opaques in depth

[Nadrieril]

Follow-up to #116821. As noted there, the current implementation doesn't detect emptiness of opaques when the opaque is nested inside a type. This doesn't matter for stable behavior (which ignores nested empty types anyway) but does matter for the exhaustive_patterns/min_exhaustive_patterns features.

This PR fixes this behavior by adding InhabitedPredicate::apply_reveal_opaque that considers opaque types when determining inhabitedness.

r? @compiler-errors

[compiler-errors]

r=me

[Nadrieril]

@bors r=compiler-errors

[bors]

📌 Commit 34307ab has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit 34307ab with merge cdd6374...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing cdd6374 to master...

[rust-timer]

Finished benchmarking commit (cdd6374): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

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

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.9%	[2.7%, 3.5%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 670.739s -> 670.687s (-0.01%)
Artifact size: 312.78 MiB -> 312.77 MiB (-0.00%)