Section CENV_SUB.

Lemma eval_expr_cenv_sub_eq {CS CS'} (CSUB: cenv_sub (@cenv_cs CS) (@cenv_cs CS')) rho:
forall e, @eval_expr CS e rho <> Vundef ->
@eval_expr CS e rho = @eval_expr CS' e rho
with eval_lvalue_cenv_sub_eq {CS CS'} (CSUB: cenv_sub (@cenv_cs CS) (@cenv_cs CS')) rho:
forall e, @eval_lvalue CS e rho <> Vundef ->
@eval_lvalue CS e rho = @eval_lvalue CS' e rho.