Lean 4 fork for HoTT-compatible kernel extensions (Path types, transport, HITs). Maintained against upstream leanprover/lean4.
75487a1bf8
This PR adds level instantiation and normalization in `getDecLevel` and `getDecLevel?` before calling `decLevel`. `getLevel` can return levels with uninstantiated metavariables or un-normalized structure, such as `max ?u ?v` where the metavariables have already been assigned. After instantiation and normalization (via `normalizeLevel`), a level like `max ?u ?v` (with `?u := 1, ?v := 0`) simplifies to `1 = succ 0`, which `decLevel` can decrement. Without this step, `decLevel` sees `max ?u ?v`, tries to decrement both arms, fails on a zero-valued arm, and reports "invalid universe level". Concretely, this fixes `for` loops with `mut` variables of sort-polymorphic type (e.g. `PProd Nat True`) where the state tuple's universe level ends up as an uninstantiated `max`. The expected-output change in `doNotation1.lean` is because the `for` loop's unit type now resolves to `Unit` instead of `PUnit` due to the improved level handling. |
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