{R : Type u_1} →
  {M : Type u_2} →
    [inst : CommSemiring R] →
      [inst_1 : AddCommMonoid M] →
        [inst_2 : Module R M] →
          {B : LinearMap.BilinForm R M} →
            {motive : B.IsSymm → Sort u} →
              ((eq : ∀ (x y : M), (B x) y = (B y) x) → motive ⋯) → (t : B.IsSymm) → motive t