Function for_each_lhs_var 

pub fn for_each_lhs_var(
    gcx: Gcx<'_>,
    expr: &Expr<'_>,
    f: &mut impl FnMut(VariableId),
)

Calls f for each resolved variable at the root of an lvalue, peeling index/slice/member/payable/unary/delete wrappers and tuple destructuring.