fix: widen transparency field to 3 bits in Meta.Config cache key#13768
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This PR fixes a bug in `Meta.Config.toKey` and `Context.setTransparency` where `TransparencyMode` was packed into only 2 bits of the cache key, even though it has 5 constructors (`.all`, `.default`, `.reducible`, `.instances`, `.none`). The `.none` case (value `4`, i.e. `0b100`) overlapped with the `foApprox` bit, which caused cache-key collisions between configurations differing only in transparency vs. `foApprox`, and `Context.setTransparency` corrupted the neighbouring bit when switching to/from `.none`. Widening the field to 3 bits and shifting every subsequent flag up by one fixes both issues. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…ne` transparency Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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This PR fixes a long-standing bug in
Meta.Config.toKeyandContext.setTransparencywhereTransparencyModewas packed into only 2 bits of the cache key, even though it has 5 constructors (.all,.default,.reducible,.instances,.none). The.nonecase (value4, i.e.0b100) overlapped with thefoApproxbit, so configurations differing only in transparency vs.foApproxcould collide in theisDefEq/WHNFcache, andContext.setTransparencycorrupted the neighbouring bit when switching to/from.none.The fix widens the transparency field to 3 bits and shifts every subsequent flag up by one. Split out from #13637 where the same fix was needed anyway to accommodate a 6th transparency constructor.
🤖 Prepared with Claude Code