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lean4/tests/elabissues/variable_universe_bug.lean
Sebastian Ullrich 8a02dfec4f feat: subsume variables under variable
/cc @leodemoura
2021-01-22 14:36:05 +01:00

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Lean4

/-
Courtesy of @rwbarton.
This is just a bug report, but since we are going to soon rewrite the entire module in Lean4,
we don't want to bother fixing the C++ bug, and we don't want to add a failing test either.
The issue is that collecting implicit locals does not collect additional universe parameters
the locals depend on.
-/
universes v u
class Category (C : Type u) :=
(Hom : (X Y : C), Type v)
variable {C : Type u} [Category.{v, u} C]
def End (X : C) := Category.Hom X X -- invalid reference to undefined universe level parameter 'v'