You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: casts.rs
    path of file: ./repos/c2rust/c2rust-refactor/src/transform
    
    the code of the file until where you have to start completion: use rustc::ty::{self, ParamEnv, TyKind};
use syntax::ast::*;
use syntax::token;
use syntax::ptr::P;
use syntax_pos::Symbol;

use crate::command::{CommandState, Registry};
use crate::driver::Phase;
use crate::matcher::{mut_visit_match_with, replace_expr, MatchCtxt};
use crate::transform::Transform;
use crate::RefactorCtxt;
use c2rust_ast_builder::mk;

#[cfg(test)]
mod tests;

/// # `remove_redundant_casts` Command
///
/// Usage: `remove_redundant_casts`
///
/// Removes all casts of the form `$e as $t` where the expression already has the `$t` type,
/// and double casts like `$e as $t1 as $t2` whe
    
    fn from(ty: ty::Ty<'tcx>) -> Self {
        use SimpleTy::*;
        match ty.kind {
            TyKind::Int(IntTy::Isize) => Size(true),
            TyKind::Uint(UintTy::Usize) => Size(false),

            TyKind::Int(int_ty) => Int(int_ty.bit_width().unwrap(), true),
            TyKind::Uint(uint_ty) => Int(uint_ty.bit_width().unwrap(), false),

            TyKind::Float(FloatTy::F32) => Float32,
            TyKind::Float(FloatTy::F64) => Float64,

            TyKind::Ref(_, ty, _mutbl) => match ty.kind {
                TyKind::Array(..) => Array,
                _ => Ref,
            }

            TyKind::RawPtr(_) | TyKind::FnPtr(_) => Pointer,

            _ => Other,
        }
    }