lean4-htt/tests/lean/run/isDefEqCheckAssignmentBug.lean
2021-01-26 16:20:41 -08:00

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Text

import Lean
open Lean
open Lean.Meta
def f (x : Type) := x
def tst : MetaM Unit := do
let m1 ← mkFreshExprMVar none
withLocalDeclD `x m1 fun x => do
trace[Meta.debug]! "{x} : {← inferType x}"
trace[Meta.debug]! "{m1} : {← inferType m1}"
let m2 ← mkFreshExprMVar (mkSort levelOne)
let t ← mkAppM ``f #[m2]
trace[Meta.debug]! "{m2} : {← inferType m2}"
unless (← fullApproxDefEq <| isDefEq m1 t) do -- m1 := f m3 -- where `m3` has a smaller scope than `m2`
throwError! "isDefEq failed"
trace[Meta.debug]! "{m2} : {← inferType m2}"
trace[Meta.debug]! "{m1} : {← inferType m1}"
let e ← mkForallFVars #[x] m2 -- `forall (x : f ?m2), ?m2`
trace[Meta.debug]! "{e} : {← e}"
return ()
set_option trace.Meta.isDefEq true
set_option trace.Meta.debug true
#eval tst