fix: handle top in addChoice after cleanup optimization
#11394
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PR leanprover#11362 added cleanup logic in `merge` that collapses `choice` values to `top` when all constructors of an inductive type are covered with all-`top` arguments. However, `addChoice` wasn't updated to handle `merge` returning `top`, causing a panic. When `addChoice` merges two constructors with the same name, the result of `merge` is placed directly in the list. With the new cleanup logic, `merge` can return `top`, which then appears in the choice list. On subsequent iterations, `addChoice` tries to match `top :: _` against `v1@(ctor i1 _) :: cs` and falls through to the panic. This fix: 1. Adds a case to `addChoice` to propagate `top` if it appears in the list 2. Checks the result of `merge` and handles `top` appropriately 3. Adds a check in `cleanup` to return `top` if any element is `top` Fixes leanprover#11393
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This problem seems to be gone again in nightly-2025-11-27. @hargoniX, I'll leave this for you to close, to make sure you know why the problem appear and disappeared! |
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This PR fixes a panic in
addChoiceintroduced by PR #11362.PR #11362 added cleanup logic in
mergethat collapseschoicevalues totopwhen all constructors of an inductive type are covered with all-toparguments. However,addChoicewas not updated to handlemergereturningtop, causing a panic.When
addChoicemerges two constructors with the same name, the result ofmergeis placed directly in the list. With the new cleanup logic,mergecan returntop, which then appears in the choice list. On subsequent iterations,addChoicetries to matchtop :: _againstv1@(ctor i1 _) :: csand falls through to the panic.This PR:
addChoiceto propagatetopif it appears in the listmergeand handlestopappropriatelycleanupto returntopif any element istopCloses #11393
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