fix: skip data-valued constructions for small-eliminating inductives - #14909
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This PR fixes elaboration of sort-polymorphic inductive types such as `inductive T : Sort u | a | b`, which previously failed with `Unknown constant `T.ctorIdx``. It also fixes the same failure for `set_option genCtorIdx false`. Such a type only eliminates into `Prop`, so it has no `T.ctorIdx` and no `SizeOf` instance. `mkNoConfusionCore` guarded against this, but `mkNoConfusionEnum` did not: `isEnumType` only rejects syntactic `Prop`, so the type was treated as an enum and `noConfusionEnum` was applied to the non-existent `T.ctorIdx`. `mkSizeOfInstances` had the same gap, and `mkSizeOfFn` then dropped a universe parameter via `recInfo.levelParams.tail!`. The recurring `recInfo.levelParams.length > indVal.levelParams.length` test is extracted as `Lean.isLargeEliminating`, resolving the `TODO: Extract to util` in `mkNoConfusionCore`. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_013tynPcTkcxEhbHRCtSLoh5
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…achim/issue14904
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This PR fixes elaboration of sort-polymorphic inductive types such as
inductive T : Sort u | a | b, which previously failed withUnknown constant `T.ctorIdx`. It also fixes the same failure forset_option genCtorIdx false.Such a type only eliminates into
Prop, so it has noT.ctorIdxand noSizeOfinstance.mkNoConfusionCoreguarded against this, butmkNoConfusionEnumdid not:isEnumTypeonly rejects syntacticProp, so the type was treated as an enum andnoConfusionEnumwas applied to the non-existentT.ctorIdx.mkSizeOfInstanceshad the same gap, andmkSizeOfFnthen dropped a universe parameter viarecInfo.levelParams.tail!.The recurring
recInfo.levelParams.length > indVal.levelParams.lengthtest is extracted asLean.isLargeEliminating, resolving theTODO: Extract to utilinmkNoConfusionCore.Fixes #14904
Co-Authored-By: Claude Opus 5 (1M context) noreply@anthropic.com
Claude-Session: https://claude.ai/code/session_013tynPcTkcxEhbHRCtSLoh5