idris-0.9.18: test/reg064/reg064.idr
sigmaEq2 : {A : Type} ->
{P : A -> Type} ->
{s1: Sigma A P} ->
{s2: Sigma A P} ->
getWitness s1 = getWitness s2 ->
getProof s1 = getProof s2 ->
s1 = s2
sigmaEq2 {A} {P} {s1 = (x ** prf)} {s2 = (x ** prf)} Refl Refl = Refl