src/librustc_middle/ty/cast.rs

   1 // Helpers for handling cast expressions, used in both
   2 // typeck and codegen.
   3
   4 use crate::ty::{self, Ty};
   5
   6 use rustc_ast as ast;
   7 use rustc_macros::HashStable;
   8
   9 /// Types that are represented as ints.
  10 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  11 pub enum IntTy {
  12     U(ast::UintTy),
  13     I,
  14     CEnum,
  15     Bool,
  16     Char,
  17 }
  18
  19 // Valid types for the result of a non-coercion cast
  20 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  21 pub enum CastTy<'tcx> {
  22     /// Various types that are represented as ints and handled mostly
  23     /// in the same way, merged for easier matching.
  24     Int(IntTy),
  25     /// Floating-Point types
  26     Float,
  27     /// Function Pointers
  28     FnPtr,
  29     /// Raw pointers
  30     Ptr(ty::TypeAndMut<'tcx>),
  31 }
  32
  33 /// Cast Kind. See RFC 401 (or librustc_typeck/check/cast.rs)
  34 #[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
  35 pub enum CastKind {
  36     CoercionCast,
  37     PtrPtrCast,
  38     PtrAddrCast,
  39     AddrPtrCast,
  40     NumericCast,
  41     EnumCast,
  42     PrimIntCast,
  43     U8CharCast,
  44     ArrayPtrCast,
  45     FnPtrPtrCast,
  46     FnPtrAddrCast,
  47 }
  48
  49 impl<'tcx> CastTy<'tcx> {
  50     /// Returns `Some` for integral/pointer casts.
  51     /// casts like unsizing casts will return `None`
  52     pub fn from_ty(t: Ty<'tcx>) -> Option<CastTy<'tcx>> {
  53         match t.kind {
  54             ty::Bool => Some(CastTy::Int(IntTy::Bool)),
  55             ty::Char => Some(CastTy::Int(IntTy::Char)),
  56             ty::Int(_) => Some(CastTy::Int(IntTy::I)),
  57             ty::Infer(ty::InferTy::IntVar(_)) => Some(CastTy::Int(IntTy::I)),
  58             ty::Infer(ty::InferTy::FloatVar(_)) => Some(CastTy::Float),
  59             ty::Uint(u) => Some(CastTy::Int(IntTy::U(u))),
  60             ty::Float(_) => Some(CastTy::Float),
  61             ty::Adt(d, _) if d.is_enum() && d.is_payloadfree() => Some(CastTy::Int(IntTy::CEnum)),
  62             ty::RawPtr(mt) => Some(CastTy::Ptr(mt)),
  63             ty::FnPtr(..) => Some(CastTy::FnPtr),
  64             _ => None,
  65         }
  66     }
  67 }