1 // Helpers for handling cast expressions, used in both
2 // typeck and codegen.
3 
4 use crate::ty::{self, Ty};
5 
6 use rustc_macros::HashStable;
7 
8 /// Types that are represented as ints.
9 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
10 pub enum IntTy {
11     U(ty::UintTy),
12     I,
13     CEnum,
14     Bool,
15     Char,
16 }
17 
18 // Valid types for the result of a non-coercion cast
19 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
20 pub enum CastTy<'tcx> {
21     /// Various types that are represented as ints and handled mostly
22     /// in the same way, merged for easier matching.
23     Int(IntTy),
24     /// Floating-point types.
25     Float,
26     /// Function pointers.
27     FnPtr,
28     /// Raw pointers.
29     Ptr(ty::TypeAndMut<'tcx>),
30 }
31 
32 /// Cast Kind. See [RFC 401](https://rust-lang.github.io/rfcs/0401-coercions.html)
33 /// (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`.
from_ty(t: Ty<'tcx>) -> Option<CastTy<'tcx>>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 }
68